A sensitive and selective electrochemical sensor based on graphene quantum dots/gold nanoparticles nanocomposite modified electrode for the determination of luteolin in peanut hulls Microchem. J. (IF 2.746) Pub Date : 2018-12-06 Jing Tang, Rong Huang, Shengbiao Zheng, Sixun Jiang, Hao Yu, Zirong Li, Jianfei Wang
A simple and sensitive electrochemical sensor based on graphene quantum dots (GQDs) and gold nanoparticles (GNPs) nanocomposite modified glassy carbon electrode (GQDs/GNPs/GCE) was developed for the determination of luteolin. The GQDs/GNPs/GCE was prepared by electrodeposition method, and characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The GQDs/GNPs nanocomposite showed excellent synergistic electrochemical activity for the oxidation of luteolin. Compared to bare GCE, the GQDs/GNPs/GCE resulted in a 16-fold increase in the oxidation current of luteolin in phosphate buffer at pH 5.0. Using the differential pulse voltammetry method, the dependence of the oxidation current vs. concentration was found to be linear from 1 × 10−8 to 1 × 10−5 M with a regression coefficient of 0.997, and the detection limit of luteolin was 1.0 nM (S/N = 3). The recovery was between 98.8% and 101.4% in peanut hull samples. This strategy might enable more opportunities for the electrochemical determination of luteolin in practical applications.
Electron rays irradiated polyaniline anchored over bovine serum albumin for simultaneous detection of epinephrine and uric acid Microchem. J. (IF 2.746) Pub Date : 2018-12-05 P. Thivya, J. Wilson
Networks of electron beam irradiated polyaniline (Irr-PANi) supported with bovine serum albumin (BSA) biocomposite is employed as electrochemical biosensor for simultaneous determination of epinephrine (EP) and uric acid (UA). Facilitated electron transfer was associated with modified biocomposite, as a result an enhancement in electro oxidation of EP and UA occurs. In Irr-PANi/BSA biocomposite, rich pore channels, conformational bahavior and redox mediator role of BSA outperformed the catalytic activity to detect EP and UA well suited for wide range of detection 500 nM–700 μM and 300 nM–800 μM with detection limits 26 and 16 nM (S/N = 3σ/b) respectively. The biofunctionalized composite has demonstrated highly sensitive, selective and reproducible electrochemical sensing for EP and UA. These characteristics of the biocomposite are extremely suitable to resolve EP and UA in black tea and chicken samples with satisfactory results.
Determination of naturally occurring thyreostats in bovine milk by high performance liquid chromatography combined with fluorescence detection Microchem. J. (IF 2.746) Pub Date : 2018-11-28 Zhongyin Ji, Yanxin Yu, Qianqian Jin, Guoliang Li, Na Hu, Wu Zhou, Yourui Suo, Zhiwei Sun, Jinmao You
This presented study describes a method based on high performance liquid chromatography combined with fluorescence detection (HPLC-FLD) using N-(2-iodoacetyl)-1-pyrenemethylamine (NIPA) as a novel fluorescence labeling reagent for the determination of thyreostats in bovine milk. Five thyreostats, belonging to the group of imidazole and thiouracil, were investigated in this work: tapazole (TAP), thiouracil (TU), methylthiouracil (MTU), propylthiouracil (PTU) and phenylthiouracial (PhTU). Thyreostats were specifically purified by a silver ion solid phase extraction (Ag-SPE) cartridge and then labeled using NIPA. The labeled derivatives showed excellent fluorescence property with maximum excitation and emission wavelengths of 330 nm and 375 nm, respectively. The labeled derivatives were separated on a reversed-phase Eclipse SB-C18 column within 12 min. Excellent linearity (R2 > 0.995) of all thyreostats was achieved with the limits of detection (LODs) and the limits of quantitation (LOQs) in the low micrograms per liter range of 0.21–0.30 μg/L and 0.70–1.00 μg/L, respectively. Satisfactory recoveries in the range of 93.5–98.0% were obtained for all thyreostats. The developed method has been successfully applied to analyze thyreostats in bovine milk with good applicability. Thirty bovine milk samples have been investigated, and varying levels of thiouracil were detected in thirteen of these samples. The highest level in the raw milk reached a value of 4.5 μg/L. To our best knowledge, this study is the first to report the presence of naturally occurring thiouracil in milk by HPLC-FLD analysis.
Replacement Orthogonal Wavelengths Selection as a new method for multivariate calibration in spectroscopy Microchem. J. (IF 2.746) Pub Date : 2018-12-02 Mohammad Goodarzi, Daniel E. Bacelo, Silvina E. Fioressi, Pablo R. Duchowicz
Wavelength selection is a critical step in multivariate calibration. Variable selection methods are used to find the most relevant variables, leading to improved prediction accuracy, while simplifying both the built models and their interpretation. In addition, different spectrophotometer designs and measurement principles result in non-destructive technologies applied in many fields, such as agriculture, food chemistry and pharmaceutics. However, an on-chip or portable device does not allow acquiring data from a large number of wavelengths. Therefore, the most informative combination of a limited number of variables should be selected. The Replacement Orthogonal Wavelengths Selection (ROWS) method is described here as a new method. This algorithm aims at selecting as few wavelengths as possible, while keeping or improving the prediction performance of the model, compared to when no variable selection is applied. The ROWS is applied to several near infrared spectroscopic data sets leading to improved analytical figures of merits upon wavelength selection in comparison to a built PLS model using entire spectral range. The performance of the ROWS-MLR method was compared to the FCAM-PLS method. The resulting models are not significantly different from those of FCAM-PLS; however, it involves a significantly smaller amount of variables.
A visualized colorimetric detection strategy for heparin in serum using a metal-free polymer nanozyme Microchem. J. (IF 2.746) Pub Date : 2018-12-03 Mengyuan Yin, Zhiqiang Duan, Chunxian Zhang, Luping Feng, Yuqi Wan, Yuanyuan Cai, Huan Liu, Shuai Li, Hua Wang
A metal-free polymer nanozyme has been developed for the first time simply via the one-pot covalent reaction of hyperbranched polyethyleneimine (PEI) and redox dihydroxybenzaldehyde (DHB). The yielded PEI-DHB nanoparticles could display the peroxidase-like catalysis activity, so as to act as the metal-free nanozyme in catalyzing the chromogenic reactions of 3,3′,5,5′-tetramethylbenzidine and H2O2. More interestingly, the catalysis activity of the polymer nanozymes could be specifically inhibited by heparin oppositely charged. A facile visualized colorimetric method was thereby developed for sensing heparin through combining the specific catalysis and electrostatic attraction of PEI-DHB nanozyme. It was found that the developed colorimetric method can enable the detection of heparin in serum over the linear concentration range of 0.050–1.0 μM, promising the wide applications for the detection of heparin in the clinical laboratory for the disease diagnostics and pharmacological monitoring. More importantly, such a green synthesis method may be tailored for fabricating various metal-free polymer nanozymes for the wide catalysis applications.
Geochemical and petrographic characterization of pyroclastic deposits of Los Humeros Volcanic Complex used as aggregates in the plasters from Teotihuacan (Mexico) Microchem. J. (IF 2.746) Pub Date : 2018-11-27 Donatella Barca, Alessandra Pecci, Luis Barba, Gino M. Crisci, Raffaella De Luca, Stefano Marabini, Linda R. Manzanilla, Agustin Ortiz, Jorge Blancas, Alejandro Pastrana, Domenico Miriello
This work presents the results of the petrographic and geochemical characterization of pyroclastic deposits outcropping in an area located to the northeast and southeast of Los Humeros Volcanic Complex, in the eastern part of the Trans-Mexican Volcanic Belt (TMVB). The results were compared with the analyses of aggregates in the plasters of Xalla in Teotihuacan (Mexico) in order to determine the provenance of the raw materials (in particular glass shards) used as aggregates. The characterization of the deposits and the raw materials used in the plasters was conducted by OM, SEM/EDS and LA-ICP-MS. Petrographic and geochemical studies have highlighted the geochemical similarity among glass shards used as aggregates in the plasters of Teotihuacan (Teopancazco and Xalla) and the pyroclastic deposits outcropping around Altotonga, a town located in the northeast of Los Humeros Caldera. This similarity shows the importance of the use of a volcanic cinder, rich in glass shards, in plasters from different areas of the Teotihuacan city. The paper also examines the characteristics of plasters – in some cases painted – from Xalla, thus confirming the re-plastering and re-painting phenomena and the use of hematite, identified by Raman Spectroscopy.
Magnetic solid phase extraction of trace paracetamol and caffeine in synthetic urine and wastewater samples by a using core shell hybrid material consisting of graphene oxide/multiwalled carbon nanotube/Fe3O4/SiO2 Microchem. J. (IF 2.746) Pub Date : 2018-11-29 Halil İbrahim Ulusoy, Erkan Yılmaz, Mustafa Soylak
A new hybrid material was synthesized including magnetic graphene oxide/multiwalled carbon nanotube core shell (GO/MWCNT/Fe3O4/SiO2) and used as magnetic solid phase extraction adsorbent for separation and pre-concentration of paracetamol and caffeine subsequent detection by high performance liquid chromatography. The morphology, composition, and properties of the synthesized hybrid material was characterized by Fourier transform infrared spectrometry, Raman spectrometry, X-ray diffraction spectrometry, scanning electron microscopy, mapping photographs and BET surface area analysis. The experimental variables on the extraction efficiency were studied and optimized. The optimum conditions for quantitative extraction of paracetamol and caffeine were obtained as of adsorbent amount, 70 mg; pH, 8.0; and elution with 1 mL of methanol by vortex mixer for 60 s. Validation experiments showed that the developed method had good linear ranges 5–800 ng mL−1 for caffeine and 10–1000 ng mL−1 for paracetamol, respectively. The limits of detection were found as 1.48 and 3.32 ng mL−1 for caffeine and paracetamol, respectively. The accuracy of the developed magnetic solid phase extraction method was proved by addition-recovery tests by using model solutions and the developed method was successfully applied for the determination of paracetamol and caffeine in synthetically prepared urine and waste water samples.
Separation and preconcentration of Pb(II) and Cd(II) from aqueous samples using hyperbranched polyethyleneimine-functionalized graphene oxide-immobilized polystyrene spherical adsorbents Microchem. J. (IF 2.746) Pub Date : 2018-11-20 Hilal Ahmad, Chaojie Cai, Changkun Liu
Accurate determination of metal ions in wastewater is essential for environmental monitoring and assessment. In aqueous media, the presence of metal ions at trace concentrations and the interference of matrices pose difficulty in its quantification. Hence, a radical way to eliminate the matrix components is to preconcentrate the target metal ions. Graphene oxide, due to their exceptional higher surface area, has received significant attention and research interest in the field of adsorption science. However, direct use of graphene oxide in preconcentration of metal ions faces irreversible aggregation and leakage from column. To overcome these challenges, we synthesized a polyethylenimine-functionalized graphene oxide-immobilized polystyrene adsorbent and employed for the column preconcentration of Pb(II) and Cd(II) from wastewater samples. The optimum pH for Pb(II) and Cd(II) preconcentration were found to be 6 and 8, respectively. The method showed a preconcentration factor of 833 and 900 and a detection limit of 1.5 ± 0.2 ng L−1 and 1.8 ± 0.3 ng L−1 for Pb(II) and Cd(II), respectively. The preconcentration limit for Pb(II) and Cd(II) were found to be 0.80 μg L−1 and 0.74 μg L−1, respectively. The PS@GOA adsorbent can be used repeatedly up to 72 cycles without any loss of the extraction efficiency. The prepared adsorbent is chemically stable, showing no leaching of graphene oxide from the column. The accuracy of the method against the systematic and constant errors was resolute by analyzing SRM 1572 and NIES 10C (<5% RSD). The method can be suitably applied for the routine analyses of Pb(II) and Cd(II) in wastewater samples. The amount of Pb(II) and Cd(II) in river water, industrial wastewater and tap water samples were found to be 3.8, 28.6, 1.2 ng mL−1 and 5.6, 2.2, and 3.2 ng mL−1, respectively. The recoveries of the analytes ranged from 98.0 to 104%. The developed method showed good reproducibility with an average error of ±4%.
A new sensitive voltammetric determination of thymol based on MnY nanozeolite modified carbon paste electrode using response surface methodology Microchem. J. (IF 2.746) Pub Date : 2018-11-27 Behnaz Aghamohseni, Seyed Karim Hassaninejad-Darzi, Mohammad Asadollahi-Baboli
In this paper, a simple voltammetric method has been reported for the thymol determination using MnY nanozeolite modified carbon paste electrode (MnY/CPE). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and N2 adsorption-desorption isotherm were used to characterize the structure of synthesized NaY and MnY nanozeolites. Also, cyclic voltammetry (CV), chronoamperometry, amperometry and differential pulse voltammetry (DPV) were used to investigate the performance of the modified electrode. The oxidation peak current of thymol was increased dramatically at the MnY/CPE surface against bare CPE and their overpotentials decreased. The effects of pH, modifier amount (MnY%), scan rate and step potential were investigated on the electrochemical response of thymol electro-oxidation based on response surface methodology. Results from this method indicated that pH of 7.0, 20% of MnY nanozeolite in the modified CPE, scan rate (0.06 V s−1) and step potential (7 mV) results in the maximum current density. Under the optimized conditions, linear response was obtained over the range of 0.5–28 μM and also, detection limits was found to be 0.243 μM by DPV method in the MnY/CPE surface. The diffusion coefficient and catalytic rate constant for the electrooxidation of thymol were calculated to be 1.5 × 10−6 cm2 s−1 and 2.6 × 105 cm3 mol−1 s−1, respectively. The fabricated electrode (MnY/CPE) showed good stability, reproducibility and repeatability as well as high recovery. The practical application of the MnY/CPE was demonstrated by measuring the concentration of thymol in thymex syrup as real samples. The proposed method is simple, rapid and inexpensive and can be utilized as a valuable analytical tool in quality control of the pharmaceutical industry.
Combination of sequential cloud point extraction and hydride generation atomic fluorescence spectrometry for preconcentration and determination of inorganic and methyl mercury in water samples Microchem. J. (IF 2.746) Pub Date : 2018-11-29 Han Zheng, Jiajia Hong, Xingling Luo, Shan Li, Meixia Wang, Bingyi Yang, Mei Wang
A sequential cloud point extraction method was established for the determination of trace mercury species in water samples by hydride generation atomic fluorescence spectrometry (HGAFS). The proposed extraction system consisted of two chief steps: isolation of inorganic mercury (Hg2+) by chelating with potassium-iodide and methyl green, and then isolation of methyl mercury (CH3Hg+) by chelating with ammonium pyrrolidinedithiocarbamate. The nonionic surfactant Triton X-114 was chosen as the extractant, while the brominating agent was applied to convert extracted CH3Hg+ into Hg2+. Before HGAFS detection, the two surfactant-rich phases obtained in the sequential process were separately diluted to 3 mL with 5% (v/v) HCl after the addition of antifoam (0.4 mL). The effects of experimental conditions, including pH and concentration of surfactant and chelating agents, on cloud point extraction were optimized. Under the optimum conditions, the limits of detection for Hg2+ and CH3Hg+ were 0.007 and 0.018 μg/L with the enrichment factors of 15.1 and 11.2, respectively. The proposed method was successfully used for the determination of trace Hg2+ and CH3Hg+ in water samples with satisfactory recoveries of 95–104%.
Surface enhancement of porous alumina microfibers toward electrochemical sensing of chlorogenic acid Microchem. J. (IF 2.746) Pub Date : 2018-11-29 Xiaofeng Yang, Zhencao Wang, Pengqin Chen, Dong Sun
Porous alumina microfibers with a diameter of 125 nm were prepared through hydrothermal reaction in urea solution using aluminium nitrate as the precursor, and characterized using transmission electron microscopy and scanning electron microscopy. The mechanism of oxidation of chlorogenic acid was examined using cyclic voltammetry, indicating a reversible two-electron process. Compared with the bare carbon paste electrode (CPE), the oxidation signals of chlorogenic acid were greatly enhanced with the alumina microfiber-modified CPE. Chronocoulometry experiments indicated that the accumulation of chlorogenic acid on the surface of the alumina microfibers was obviously improved relative to that on the bare electrode, which is attributed to the numerous micropores and regular fiber-like structures. Based on the signal amplification ability of the porous alumina microfibers, a novel electrochemical sensing platform was developed for chlorogenic acid. The linear range was 10–2000 μg L−1, and the limit of detection was evaluated to be 5.0 μg L−1. The practical application of this new method was demonstrated using honeysuckle and soft drink samples. The results were consistent with the values obtained by high-performance liquid chromatography.
Simultaneous removal of binary dye from textile effluent using cobalt ferrite-alginate nanocomposite: Performance and mechanism Microchem. J. (IF 2.746) Pub Date : 2018-11-27 Jayalakshmi R., Jeyanthi J.
The rapid removal of dye effluent containing two or more dyes is in demand due to its significant environmental issues. The present communication deals with the simultaneous adsorption of Reactive red 195 (RR195) and Reactive yellow 145 (RY145) from a textile dye effluent in a binary component system. Cobalt ferrite-alginate nanocomposite synthesized by ex-situ polymerization was employed as an adsorbent for the removal of binary dye effluent. The first order derivative spectrophotometric method was applied for the simultaneous quantification of RR195 and RY145 in binary solutions. The binary adsorption equilibrium could be achieved within 60 min, and the adsorption process followed pseudo second order kinetics. The removal efficiency could be maintained in a wide pH range of 3–6. The presence of amine, hydroxyl, carbonate and ferrite groups on the adsorbent surface played a vital role in the removal of RR195 and RY145 from their binary mixture. The continuous adsorption experiments revealed that the breakthrough time and exhaustion time increases with an increase in the bed height. The experimental results present new sustainable, cost effective biocompatible nanocomposite as a potential adsorbent for the removal of real-time dye effluent. Moreover, it is magnetically separable and reusable. The cobalt ferrite-alginate as a sole nanocomposite is capable of eliminating the whole dye content from a mixture and serves as a better solution for effective water remediation.
Low-cost and green dispersive solid phase extraction of hydrophilic compounds using titanium dioxide nanoparticles Microchem. J. (IF 2.746) Pub Date : 2018-11-28 Szymon Dziomba, Aleksandra Pawelec, Krzesimir Ciura, Marta Dolegowska, Anna Klimowska, Wojciech Rodzaj, Mohamed Guerrouache, Benjamin Carbonnier, Bartosz Wielgomas
Selective extraction of hydrophilic compounds is a challenging task for analytical laboratories. In an attempt to address this issue, application of titanium dioxide nanoparticles as a dispersive solid phase extraction sorbent was investigated. In the study, three model analytes were used for method optimization: flavin mononucleotide, thiamine monophosphate and thiamine pyrophosphate. The influence of various parameters on sorption and desorption process was evaluated. Under optimized conditions, the sorption was performed in a presence of 1 M formic acid (pH 1.9) for 10 min under vortex stirring providing efficiency up to 94%. The influence of salt content in sample matrix was found to be negligible while the organic solvent presence slightly improved the sorption efficiency. Elution of analytes from TiO2 sorbent was obtained with both aqueous ammonia and phosphate buffer (pH 11.8) solutions. Under optimized conditions dispersive solid phase extraction method was shown to provide high selectivity with extraction recoveries >89.0% for studied compounds. The susceptibility of the method on various matrices was assayed for extraction of model analytes from enriched tap water, milk, apple juice and human urine samples. Moreover, the methodology was applied for phospholipids removal from pharmaceutical formulation (lecithin microemulsion) of propofol. Due to the utilization of titanium dioxide nanoparticles, the cost of sample preparation step was estimated to be about 0.1 Euro per sample, providing >100-fold reduction of the price for typical analysis using titanium dioxide microspheres.
Developing a new and simple ultrasound-assisted emulsification liquid phase microextraction method built upon deep eutectic solvents for Patent Blue V in syrup and water samples Microchem. J. (IF 2.746) Pub Date : 2018-11-28 Gulsah Saydan Kanberoglu, Erkan Yilmaz, Mustafa Soylak
In this study, Deep Eutectic Solvents (DESs) were utilized for ultrasound-assisted emulsification liquid phase microextraction (UA-ELPME) of Patent Blue V in syrup and water samples. Patent Blue V in sample solution of pH 4.0 was extracted into DES phase prepared from choline chloride and phenol. Concentration of Patent Blue V in final DES phase was measured at 627.5 nm with Uv-Vis spectrophotometry. Sample volume, pH, matrix effect, volume and type of DES, ultrasonication and centrifugation times were investigated and optimized. The developed UA-ELPME method presents a limit of detection (LOD) of 0.37 μg L−1, preconcentration factor of 15 and a relative standard deviation (RSD, %) of 6.0% under the optimum conditions. The validation was carried out with standard addition-recovery experiments for syrup and water samples. The obtained recovery results showed that the developed UA-ELPME method was applicable for routine Patent Blue V analysis in syrup and water samples.
Ultrasensitive immunoassay of breast cancer type 1 susceptibility protein (BRCA1) using poly (dopamine-beta cyclodextrine-Cetyl trimethylammonium bromide) doped with silver nanoparticles: A new platform in early stage diagnosis of breast cancer and efficient management Microchem. J. (IF 2.746) Pub Date : 2018-11-16 Mohammad Hasanzadeh, Mahsa Feyziazar, Elham Solhi, Ahad Mokhtarzadeh, Jafar Soleymani, Nasrin Shadjou, Abolghasem Jouyban, Soltanali Mahboob
Breast cancer type 1 susceptibility protein (BRCA1) is antioncogenes in women, who are genetically predisposed to breast cancer. Therefore, development of a reliable method for sensitive and selective detection of BRCA1 with low concentration level is very important. In this research work a novel immunoassay based on signal amplification strategy of multiple polymers to recognition of BRCA1 protein was developed. The engineered immunoassay prepared by poly (dopamine-beta cyclodextrine-Cetyl trimethylammonium bromide doped by silver nanoparticles (P[DA-β-CD/CTAB])-AgNPs) and functionalized mesoporous silica (MCM-41-SO3H) composite fabricated on the glassy carbon electrode with a large surface area which was prepared a new platform to immobilization of primary antibodies and provide excellent conductivity. To further amplify the electrochemical signal, MCM-41-SO3H provides suitable pores volume and functional groups to capture more horseradish peroxidase-labeled antibodies (HPR-Ab2) and enhances the conductivity. The proposed immunoassay displays suitable analytical performance for the monitoring of BRCA1 with a linear range from 0.01565–10 pg/mL (by DPV) and 0.625–20 pg/mL (by SWV) and a low limit of quantification of 0.003 pg/mL. Also, satisfactory results are obtained for the determination of BRCA1 in human plasma samples and MCF-7 cancer cell lysates, indicating the potential of the immunoassay to be applied in clinical analysis.
Fabrication and characterization of high-branched recyclable PAMAM dendrimer polymers on the modified magnetic nanoparticles for removing naphthalene from aqueous solutions Microchem. J. (IF 2.746) Pub Date : 2018-11-27 Shahrzad Aliannejadi, Amir Hessam Hassani, Homayon Ahmad Panahi, Seyed Mehdi Borghei
In this study, magnetic nanoparticles (MNPs) modified with poly amidoamine (PAMAM) dendrimers - by adding methyl acrylate and ethylenediamine continuously till 10th generation- which further anchored to benzaldehyde ligand through polymeric bonding and studied as a novel method for synthesizing a nano sorbent for removing naphthalene (NAP) from aqueous environments. Synthesized nanopolymer was characterized by Fourier transform infrared spectroscopy (FTIR), Field-Emission Scanning Electron Microscopy (FE-SEM) equipped with EDS, X-ray Diffraction (XRD), Vibrating Sample Magnetometry (VSM), thermal gravimetric analysis (TGA). Based on the obtained analysis results synthesized average nanocomposite diameter is 25–55 nm. In batch experiments, operative parameters in adsorption process like pH, sorbent dosage, contact time and initial concentration of NAP have investigated, and maximum adsorption for NAP by sorbent in optimal adsorption conditions examined. Therefore, synthesized nanocomposite used for removing NAP from real water samples and industrial wastewater containing complex matrices and all of them analyzed by Gas Chromatography-Mass spectrometry (GC-MS). The NAP removal efficiency of 93–100% obtained from water in the river, sea and industrial waste. Also, fitting the adsorption process with various isotherm models and kinetic studies designated that the equilibrium data follow from the Langmuir model (R2 = 0.9957) and adsorption kinetic from the pseudo-second-order model (R2 = 0.9999). Maximum adsorption capacity for sorbent was qmax = 101 mg g−1. As a result, synthesized magnetic dendrimers have high adsorption capacity without no environmental pH adjustment which is recyclable for four-times as an efficient sorbent used for removing NAP from aqueous solutions.
High performance cypermethrin pesticide detection using anatase TiO2-carbon paste nanocomposites electrode Microchem. J. (IF 2.746) Pub Date : 2018-11-28 Muhammad Nurdin, Maulidiyah Maulidiyah, La Ode Agus Salim, Muhammad Zakir Muzakkar, Akrajas Ali Umar
The role of anatase TiO2 in the performance of carbon paste electrodes (CPE) electrochemical sensors for detection of cypermethrin pesticide has been investigated. It was found that the anatase TiO2-CPE nanocomposites electrode exhibits excellent sensitivity towards the cypermethrin and its sensing sensitivity increases with the increasing of anatase TiO2 concentration and optimum at a concentration of 2 w/w (CPE is ~3 w/w). The detection limit of the nanoelectrode can be down to the level of ~ 0.1 ppm, which is below the maximum residual limits of cypermethrin in the environment (~ 0.5 ppm) and is in the allowed limit for food products (~0.05 to 0.2 ppm). The nanoelectrode is also excellent in the chemical stability with a performance decreasing (%RSD) is only ~0.37% for 11 times repeated measurement. The enhancement of the electron transfer rate in the present of anatase TiO2 in the CPE matrix as the result of excellent physico-chemical properties of anatase TiO2 is considered as the key reason for the enhanced performance. The anatase TiO2-CPE system should find potential application in cypermethrin pesticide monitoring in environment and agricultural products control.
Direct analysis of high-purity cadmium by electrothermal vaporization-inductively coupled plasma optical emission spectrometry Microchem. J. (IF 2.746) Pub Date : 2018-11-07 Nickolay S. Medvedev, Olga V. Lundovskaya, Anatoly I. Saprykin
The paper presents the original technique of trace analysis of solid cadmium samples by the optical emission spectrometry with inductively coupled plasma in combination with the electrothermal vaporization (ETV-ICP-OES). The temperature program for heating ETV provides almost complete evaporation of cadmium (at 900 °C) and the subsequent vaporization of analytes when the temperature ETV rises up to 2400 °C. Separate vaporization of matrix and analytes provides reducing of spectral interferences, which ensures lower the limits of detection of the analytes (LODs). Evaluation of the analytical characteristics of the proposed technique shows that the ETV-ICP-OES allows us to reduce the detection limits of Al, Au, Be, Bi, Co, Cr, Fe, Ga, In, Mn, Ni, Re, Sn and V from 3 to 670 times compared with traditional ICP-OES analysis of 2% cadmium solutions. The accuracy of proposed technique was confirmed by analysis of cadmium samples by an independent ICP-MS technique and by addition and recovery experiment.
Evaluations of environmental hazard parameters of natural and some artificial radionuclides in river water and sediments Microchem. J. (IF 2.746) Pub Date : 2018-11-20 Özlem Selçuk Zorer
In order to evaluate the radiological baseline in the Lake Van basin, 238U, 232Th, 226Ra, 137Cs and 40K activity concentrations and gross radioactivity were determined in twelve river water and sediment samples. To determine radionuclide activities and gross radioactivity, a gamma ray spectrometer with HPGe detector and a gross-alpha/beta-counting system low background multi-detector were used, respectively. Therefore, based on the measured activity concentrations, parameters of radiological hazards such as radium equivalent activity, outdoor absorbed dose rate, annual effective dose, and internal and external hazard indices were calculated. Req, Hex and Hin values in samples were generally lower than worldwide average values; while Dout and AED values were higher than worldwide average values in general.
Deep eutectic solvent based liquid phase microextraction of nickel at trace level as its diethyldithiocarbamate chelate from environmental samples Microchem. J. (IF 2.746) Pub Date : 2018-11-22 Zeliha Erbas, Mustafa Soylak, Erkan Yilmaz, Mehmet Dogan
A new and green deep eutectic solvent based liquid phase microextraction procedure (DES-LPME) has been developed for separation and preconcentration of nickel prior to micro-sampling flame atomic absorption spectrometric determination (MS-FAAS). Ni(II) was complexed with sodium diethyldithiocarbamate (NaDDTC) and was extracted to micro-volume DES phase. In this regard, tetra butyl ammonium chloride-decanoic acid component as 1:3 molar ratios was used to prepare DES. Analytical parameters such as pH of sample solution, sample volume, volume of DES and matrix effect that would affect the recoveries of nickel(II) were optimized. Quantitative recovery values for Ni(II) ions were obtained at pH 3.0. The preconcentration factor (PF) was calculated as 60. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be as 0.13 μg L−1 and 0.43 μg L−1 respectively. The relative standard deviation (% RSD) was 3.2%. The validation of the developed method was proved by the analysis of the certified water reference materials and addition-recovery test. The presented deep eutectic solvent based liquid phase microextraction method (DES-LPME) was successfully applied for determination of nickel in some water and food samples from Turkey.
Determination of iodide based on dynamic gas extraction and colorimetric detection by paper modified with silver triangular nanoplates Microchem. J. (IF 2.746) Pub Date : 2018-11-26 Marina O. Gorbunova, Anastasiya A. Baulina, Margarita S. Kulyaginova, Vladimir V. Apyari, Aleksei A. Furletov, Alexey V. Garshev, Stanislava G. Dmitrienko
This paper reports on a new method for sensitive and selective determination of iodide based on dynamic gas extraction with air flow and digital colorimetric detection using paper modified with silver triangular nanoplates (AgTNPs). Iodide is oxidized in a sample by Fe(III) to produce molecular iodine which is extracted in air flow and transferred to a sensitive AgTNPs-containing paper layer. Interaction of AgTNPs with iodine results in optical changes which can be monitored by ordinary scanner. The high selectivity of dynamic gas extraction to volatile compounds ensures successful analysis of such samples as cranberry and kelp with no sample pretreatment, and due to the sensitivity of AgTNPs good analytical performance can be achieved. The limit of detection of iodide was found to be of 0.01 mg L−1 and the determination range of 0.03–0.3 mg L−1. The method can be easily adapted to simultaneous determination of iodide/iodine and iodide/chloride in the same sample.
High-fluorescent carbon dots (CDs) originated from China grass carp scales (CGCS) for effective detection of Hg(II) ions Microchem. J. (IF 2.746) Pub Date : 2018-11-27 Guanhong Liu, Haishuang Jia, Na Li, Xinyi Li, Zhiyue Yu, Jun Wang, Youtao Song
Carbon dots (CDs) as a kind of environment-friendly fluorescent nanomaterial has been actively studied because of wide and potential applications, such as bioimaging and biosensors. It is worth mentioning that preparing CDs from the recycling of carbonaceous waste has received considerable research interest. We proposed a simple carbon dots synthesis technique, that is, using China grass carp scales (CGCS) as original and green materials by a one-step microwave hydrothermal method to prepare CDs. Since the mercury ion has strongly sulphophile, S atoms display higher thermodynamic affinity and faster integrating process with Hg2+ ions. Due to the presence of large amount of cysteine-containing sulfhydryl groups, the obtained CGCS-CDs can be used as a specific fluorescence probe for detecting Hg2+ ions. Subsequently, CGCS-CDs were characterized by HR-TEM, XRD, FT-IR and XPS analyses. The optical properties of CGCS-CDs were elucidated by fluorescence and UV–vis spectra. Additionally, the effects of pH values and salt concentrations on optical properties of CGCS-CDs were also researched by fluorescence spectra. Under optimal conditions, the decrease of fluorescence intensity displays a good linear relationship with allowable Hg2+ ion detection concentration range of 0.014–30 μmol/L and a limit of detection (LOD) of 0.014 μmol/L is acquired. Meanwhile, the effect of other metal ions on the detection of Hg2+ ions by using CGCS-CDs as fluorescence probe was studied, suggesting that the CGCS-CDs could be an excellent fluorescence probe for the detection of Hg2+ ions. Eventually, the CGCS-CDs were proven to be low toxicity and applied for Hg2+ ions detection in lake water and cosmetic, demonstrating their potential towards diverse applications.
Efficient metal ion adsorption and photodegradation of Rhodamine-B by hierarchical porous Fe-Ni@SiO2 monolith Microchem. J. (IF 2.746) Pub Date : 2018-11-26 Manisha Sharma, Jasminder Singh, Soumen Basu
The presence of toxic contaminants (like heavy metal ions and dyestuffs) in water causes an environmental threat and are challenging to discrete out from the water. Now a days, to overcome the challenge of the conventional process as well as for removal of these contaminants from water, mesoporous materials are used as an adsorbent or degradant. In this work, porous rock like bimetal-oxide monolith (Fe-Ni@SiO2) was synthesized via sol-gel method. Adsorption of heavy metal ions and photocatalytic degradation of Rhodamine B (RhB) dye by using Fe-Ni@SiO2 monolith was carried out. Adsorption experiments were performed in different batches by varying several parameters. The equilibrium between Fe-Ni@SiO2 and metal ion solution was achieved in approximately 70 min time at pH 6. The equilibrium data found to be well fitted using Freundlich and Langmuir adsorption isotherms. The maximum adsorption efficacy for Pb(II) and Cd(II) ions was 1018 mg/g and 974 mg/g, respectively. The adsorption process was found to be spontaneous and exothermic in nature. Also, for the RhB dye, the photocatalytic efficiency of the Fe-Ni@SiO2 monolith (using different amount) has been calculated under visible light source. We acquired the best results using 0.10 g/L Fe-Ni@SiO2 monolith and a further increase in the amount of photocatalyst result in an increase in opacity of the solution inside the reactor. The findings from this study suggests that the Fe-Ni@SiO2 monolith shows promising results for water treatment and could be employed as an alternative adsorbent/photocatalyst for toxic metal ion adsorption and dye degradation.
Electrochemical behaviour and voltammetric determination of mercury (II) ion in cupric oxide/poly vinyl alcohol nanocomposite modified glassy carbon electrode Microchem. J. (IF 2.746) Pub Date : 2018-11-16 A. Karthika, V. Ramasamy Raja, P. Karuppasamy, A. Suganthi, M. Rajarajan
A novel poly vinyl alcohol supported cupric oxide nanocomposite (CuO/PVA) modified glassy carbon electrode (GCE) was developed for determination of mercury (II) ions by electrochemical methods. The CuO/PVA nanocomposite was synthesized by sonochemical method and characterized by spectral, analytical and electrochemical methods. Interestingly, cyclic voltammetry results exhibited that excellent electrocatalytic activity and improved sensitivity for the determination of Hg2+ ions bare to bare GCE under the optimized conditions. The CuO/PVA nanocomposite modified GCE for Hg2+ ion detection was provided a wide linear response range (10–70 μM) of response and lower detection limit (0.42 nM) respectively. The CuO/PVA/GCE showed good selectivity towards Hg2+ ion detection even in the presence of interferents such as arsenic, cadmium, lead, chromium and nickel. The proposed fabricated CuO/PVA/GCE sensor was exhibited good reproducibility for the selective determination of mercury in river and tap water and obtained good recovery results.
Impact of humic acids, temperature and stirring on passive extraction of pharmaceuticals from water by trihexyl(tetradecyl)phosphonium dicyanamide Microchem. J. (IF 2.746) Pub Date : 2018-07-21 Hanna Męczykowska, Piotr Stepnowski, Magda Caban
One of the most promising tools for the long-term monitoring of pharmaceuticals in the water environment is passive extraction techniques. A necessary step in passive sampling calibration is the determination of the sampling rates (Rs) for target analytes. This process is carried out primarily in laboratory conditions due to practical reasons. However, one should take into account the significant impact of the environmental factors that differentiate the studied aquatic environments, such as temperature, pH, salinity, water flow or the presence of dissolved organic matter (DOM). In this paper, the results of the calibration of the new PASSIL (PASsive Sampling with Ionic Liquids) sampler was performed for the first time with an examination of the effects of temperature, donor phase stirring and the concentration of humic acids, representing dissolved organic matter (DOM), using both deionized and environmental water. A slight influence of the above-mentioned factors on the extraction efficiency was observed. The determined sampling rates, however, differed in particular when the values obtained from experiments carried out using different donor phase stirring were compared. The study of the process kinetics coupled information of both the extraction efficiency and the sampling rates. The general conclusion is that the calibration of passive samplers should be performed with respect to the water parameters of the tested environment, both for the presented new technique (PASSIL) and already known techniques.
Highly sensitive detection of bisphenol A in real water samples based on in-situ assembled graphene nanoplatelets and gold nanoparticles composite Microchem. J. (IF 2.746) Pub Date : 2018-11-23 Jiao Zou, Guo-Qing Zhao, Jie Teng, Qi Liu, Xin-Yu Jiang, Fei-Peng Jiao, Jin-Gang Yu
The in-situ assembly of well-dispersed gold nanoparticles (AuNPs) and graphene nanoplatelets (GNPs) composite was carried out. The GNPs-AuNPs composite was characterized by Raman spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). GNPs-AuNPs modified glassy carbon electrode (GNPs-AuNPs/GCE) was fabricated, and its electrochemical behaviors were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The highly sensitive and selective determination of bisphenol A (BPA) at GNPs-AuNPs/GCE in sulfuric acid solution was observed by DPV. Plots of peak currents versus BPA concentrations were fitted successfully to obtain a linear relationship and a nonlinear relationship in the BPA concentration range of 5 × 10−3–100 μM and 0.05–500 nM with good coefficient of determination (R2), respectively. The limit of detection (LOD) was calculated to be 0.027 nM. The recoveries of quantitative analysis of BPA in mountain spring water and tap water at GNPs-AuNPs/GCE were in the range of 96.9%–103.3% and 97.9%–104.2%, with relative standard deviation (RSD) in the range of 0.12–1.10% and 0.48–1.78%, respectively. The GNPs-AuNPs/GCE possessed good anti-interference ability, stability, repeatability, and reproducibility. It could be used as a simple, fast and sensitive electrochemical sensor electrode for determining trace amount of BPA in water samples.
Qualitative and quantitative multivariate strategies for determining paprika adulteration with SUDAN I and II dyes Microchem. J. (IF 2.746) Pub Date : 2018-11-23 Cristina Márquez, Itziar Ruisánchez, M. Pilar Callao
Two strategies based on multivariate qualitative and quantitative analysis are proposed for determining whether paprika samples are adulterated with Sudan I or II dyes. The samples were characterized by their UV–visible spectrum. Then, the following chemometric techniques were applied: principal component analysis (PCA) for the data exploration stage, partial least squares-discriminant analysis (PLS-DA) for the qualitative strategy and partial least squares (PLS) for the Sudan quantification strategy. Three classes were considered in the qualitative analysis: unadulterated, adulterated with Sudan I and adulterated with Sudan II. For the quantitative analysis, models were developed for each adulterant in a concentration range of 0–12 mg g−1, where 0 mg g−1 stands for the unadulterated samples. Both strategies gave satisfactory results. The multi-class PLS-DA model properly differentiate between the three types of studied samples: non-adulterated and adulterated with Sudan I and with Sudan II. Only samples at the lowest concentration (1 mg g−1) were wrongly detected as unadulterated. The PLS models were validated by setting the regression line of the model-predicted concentration versus the real concentration for the test set samples. The slope and intercept of each regression line were compared with those of the ideal line (0, 1) by means of the joint test of ordinate and slope.
Xanthene based spectroscopic probe for the analysis of HCV antiviral, daclatasvir dihydrochloride, through feasible complexation reaction Microchem. J. (IF 2.746) Pub Date : 2018-11-22 Mohamed A. Abdel-Lateef, Mahmoud A. Omar, Ramadan Ali, Sayed M. Derayea
Two simple and rapid analytical assay methods were developed and validated utilizing spectroscopic techniques for sensitive and selective estimation of daclatasvir dihydrochloride in pharmaceutical preparations based on anion pair complex formation with eosin Y. The maximum absorbance of the formed complex was achieved at 545 nm in 0.1 M acetate buffer at pH 3.2 and Beer's law for absorbance against daclatasvir dihydrochloride concentration obeyed in the range of 1.0–10.0 μg mL−1 for the spectrophotometric method (method I). The technicality of spectrofluorimetric method (method II) based on measuring the quenching effect of daclatasvir dihydrochloride on the native fluorescence intensity of eosin Y at the same pH and the measurements were accomplished at 543 nm after excitation at 301 nm. The rectilinear calibration graph between daclatasvir dihydrochloride concentration and the fluorescence quenching values (ΔFI) was achieved over the range of 0.1–2.0 μg mL−1. The formation constant for the binary complex was 4.4 × 104 and Gibb's free energy change was −2.7 × 104 J mol−1. Both methods were validated in agreement with ICH guidelines and a successfully applied for the analysis dosage forms with good % recovery. A suggestion for the reaction pathway was supposed.
Selection of derivatisation agents for chlorophenols determination with multicriteria decision analysis Microchem. J. (IF 2.746) Pub Date : 2018-11-14 Marta Bystrzanowska, Renata Marcinkowska, Francisco Pena-Pereira, Marek Tobiszewski
The paper shows very systematic method of selection of derivatisation agents for a given group of analytes. In this study 8 derivatisation agents are assessed for their capability to derivatise 8 chlorophenols. Multicriteria decision analysis is used to combine many objectives of derivatisation agents selection into single, easy to be interpreted numerical value. Three basic analyses were performed to obtain rankings with the aims to assess derivatisation reaction, chromatographic separation of derivatised analytes and greenness of derivatisation agents. The first assessment showed acetic anhydride to be the most favourable alternative, the second one indicated N,O‑bis(trimethylsilyl)trifluoroacetamide (BSTFA) - chlorotrimethylsilane (TMCS) mixture to give the best separation and the third proved heptafluorobutyrylimidazole (HFBI) to be the greenest agent. Fourth, comprehensive assessment showed BSTFA:TMCS to have the best total performance. Multicriteria decision analysis can be successfully applied in analytical procedure multi-objective optimisation, at the stage of derivatisation agent selection.
Comparison of AQbD and grid point search methodology in the development of micellar HPLC method for the analysis of cilazapril and hydrochlorothiazide dosage form stability Microchem. J. (IF 2.746) Pub Date : 2018-11-20 Biljana Otašević, Jasmina Šljivić, Ana Protić, Nevena Maljurić, Anđelija Malenović, Mira Zečević
The development of stability-indicating method with isocratic elution mode based on micellar liquid chromatography for the analysis of cilazapril, hydrochlorothiazide and their degradation products was the primary aim of the present research. Since this could be done using different methodologies, two approaches were selected and comprehensively compared. The first one was risk based quality by design concept adopted by many analysts since it ensures development of robust analytical methods. The second one was multicriteria decision making approach currently interpreted in a form of experimental design complemented with grid point search is well established over past decades as a very useful way to govern analytical method development. Major drawback of later approach, related to method robustness evaluation, was discounted through proposition of simple and efficient computational procedure. Both methodologies ultimately resulted in successful chromatographic separations of all investigated substances which included analysis on XTerra RP 18 (3.9 × 150 mm, 5 μm) column with temperature set at 30 °C, mobile phase consisting of acetonitrile and Brij L23 aqueous solution (18 mmol L−1, pH 3.8) in ratio 13:87 (%, v/v) pumped at 1 mL min−1 flow rate while UV detection was performed at 215 nm. Both the 3D representation of a design space as well as grid obtained with later approach pointed out that the method performance criteria would not be compromised when amount of acetonitrile amount varies in range 12–14% (v/v), pH of the water phase in range 3.4–4.0, while concentration of Brij L23 aqueous solution can be within 15–20 mmol L−1. Hence, although the method development was based on different starting hypothesis, both methodologies enabled achievement of reliable and robust analytical methods that could serve in monitoring of cilazaprile and hydrochlorothiazide combined dosage form stability.
A chemiluminescence aptasensor based on Cu/Co nanorods for microcystin-RR detection Microchem. J. (IF 2.746) Pub Date : 2018-11-19 Bingru Liu, Xiaohua Li, Sumin Liu, Xu Hun
In this work, a chemiluminescence (CL) aptasensor was designed for detection of microcystin-RR (MC-RR) by introducing Cu/Co nanorods acting as CL catalyzer. Cu/Co nanorods were firstly synthesized throughout a hydrothermal method. Then the thiolated MC-RR aptamer was immobilized on the surface of Cu/Co nanorods, which was employed for recognizing of MC-RR target. In the presence of MC-RR, the conformational change of MC-RR aptamer was happened via recognizing between MC-RR and its aptamer. The luminol CL was catalyzed by Cu/Co nanorods that influenced by conformational change of MC-RR aptamer. The formed MC-RR/aptamer composite prevented the diffusion channel of luminol substrate toward the Cu/Co nanorods surface and restrained the Cu/Co nanorods catalyzing luminol CL. And the intensity of CL depended on the concentration of MC-RR. Under optimal condition, the CL aptasensor had a linear range in 0.1 to 70 nM and a low detection limit of 3.3 × 10−11 M for MC-RR. This study provided a significant method for MC-RR detection in real samples with excellent selectivity.
Quantitative determination of rare earth elements in scheelite via LA-ICP-MS using REE-doped tungstate single crystals as calibration standards Microchem. J. (IF 2.746) Pub Date : 2018-11-09 Yuqiu Ke, Yijian Sun, Peijun Lin, Jianzong Zhou, Zhifeng Xu, Caifang Cao, Yan Yang, Shenghong Hu
The lack of homogeneous and matrix-matched scheelite reference materials makes it difficult for quantitative determination of rare earth element (REE) concentrations in scheelite via LA-ICP-MS. In this work, three REE-doped tungstate single crystals (i.e., Dy:NaGd(WO4)2, Yb:NaGd(WO4)2, and Nd:NaGd(WO4)2) were selected as calibration standards. REEs in these crystals were found to distribute homogeneously with desirable homogeneity (signal intensity RSD < 4%). To determine the effective concentration of REEs in these crystals, three dissolution methods were comparatively studied for dissolving tungstate single crystals as well as scheelite, the results were precise (RSD: 0.15–3.21%) among these dissolution methods and consistent with reference values (obtained by EPMA or reported values) with ratios of pneumatic nebulization ICP-MS (pretreated by HNO3 + HF/HNO3 + HF + H3PO4/HNO3 + HF + tartaric acid) to EPMA 0.98–1.07%. Therefore, the simplest dissolution method (i.e., HNO3 + HF) was proposed for dissolving tungstate single crystals and scheelite. After that, REE concentrations in these crystals were treated as reference values to calibrate those in scheelite. REE concentrations in scheelite detected by LA-ICP-MS agreed well with those detected by pneumatic nebulization ICP-MS with relative percentage differences < 5% except for Yb (7.07%). It can be concluded that tungstate single crystals can be applied to calibrating REE concentrations in scheelite, and therefore an analytical method for quantitative determination of REE concentrations in scheelite via LA-ICP-MS using tungstate single crystals as calibration standards was successfully established.
Doping, structural, optical and electrical properties of Ni2+ doped CdO nanoparticles prepared by microwave combustion route Microchem. J. (IF 2.746) Pub Date : 2018-10-31 R.O. Yathisha, Y. Arthoba Nayaka, P. Manjunatha, M.M. Vinay, H.T. Purushothama
This work outlines the synthesis of pure CdO and Ni-CdO nanoparticles with different weight percentage (2, 4, 6, 8 and 10 wt%) of Ni2+ through microwave combustion route using cadmium nitrate and nickel nitrate as precursors and ethylene glycol as solvent. The morphological, optical and electrical properties of the material obtained after calcination was systematically characterized for various physicochemical properties and photoconductivity characteristics. The X-ray diffraction study of the synthesized and calcinated CdO and Ni-CdO nanoparticles confirms the existence of cubic phase with no impurity peaks (up to 4 wt%). The average crystalline size is found to be in the range of 41–47 nm based on Debye-Scherrer formula calculation. The scanning electron micrograph reveals that the synthesized samples are prismatic to spherical shaped and also it is observed that, the porosity enhances with increase in the concentration of Ni2+ ions. Energy dispersive X-ray micrographs show the existence of Ni2+ in the Ni-CdO samples. The optical bandgaps of synthesized samples are determined by Tauc's plot. Transmission electron microscope images are in accordance with the surface morphologies of scanning electron micrographs. The current-voltage characteristic (I–V) of CdO and Ni-CdO films shows that the photo current of CdO and Ni-CdO films is greater in UV-light as compared to dark.
Comparative study of antimony exposition by cigarettes and alternatives of tobacco consumption Microchem. J. (IF 2.746) Pub Date : 2018-11-16 María Carolina Talio, Mariano Acosta, Liliana Patricia Fernández
A comparative study of Sb(III) exposition is presented. The determination of trace amounts of Sb(III) present in tobacco samples (tobacco of conventional cigarettes, refill solutions for e-cigarettes, snuff used in water pipe, snus and dry rapé) has been realized by solid surface fluorescence using alizarin as fluorogenic reagent (λem = 450 nm, λexc = 363 nm). In a first step, a chemisorption on filter paper was carried out with the bile salt sodium cholate (pH 10.2). In these conditions, the metal was selectively retained on the solid support preventing the spectral interferences of the complex matrix. The calibration graphs resulted linear in the range of 0.24 to 304.4 μg L−1 with detection limit of 0.08 μg L−1 (S/N = 3.3). Results were truenessed by ETAAS with adequate agreement. The results will be used in prevention workshops for the purpose to provide scientific evidence to serve young people to make a correct decision respect the tobacco consumption.
Improved QuEChERS and solid phase extraction for multi-residue analysis of pesticides in paddy soil and water using ultra-high performance liquid chromatography tandem mass spectrometry Microchem. J. (IF 2.746) Pub Date : 2018-11-15 Siti Zulfa Zaidon, Yu Bin Ho, Hazwanee Hamsan, Zailina Hashim, Nazamid Saari, Sarva Mangala Praveena
Two new sensitive and selective methods were developed to quantify thirteen pesticides in soil and water. The method developed in soil was optimized and modified based on the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuECHERS) procedure, followed by a dispersive solid phase extraction (dSPE) clean-up technique. The method developed in the water samples was based on glass fiber and nylon filtration, followed by the solid phase extraction (SPE) clean-up technique. Both methods used ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) for analysis. The developed method showed good linearity at calibration points ranging from the instrumental quantification limit (IQL) to 500 ng mL−1, and the correlation coefficients (R2) for all of the target analytes were higher than 0.9990. The method showed recoveries ranging from 74% to 111% in soil and 77% to 117% in water. The method detection limit (MDL) for all of the target analytes ranged from 0.03 ng g−1 to 0.4 ng g−1 in soil and 0.1 ng L−1 to 10 ng L−1 in water. Both methods were applied to field paddy soil and water samples to quantify pesticide residues in the samples. Isoprothiolane was the highest concentration pesticide in paddy soil (34.81 ng g−1), whereas chlorantraniliprole (11.83 ng mL−1) was the highest concentration pesticide in the paddy water sample. Based on the instrument and method performance validation results, the developed methods can be applied as part of pesticide residue analysis in environmental and agricultural matrices, thus aiding in regulating and monitoring pesticide usage in agricultural fields.
Bismuth-tin-film electrodes for Zn(II), Cd(II), and Pb(II) trace analysis Microchem. J. (IF 2.746) Pub Date : 2018-11-22 Matjaž Finšgar, Barbara Petovar, Katja Vodopivec
The focus of this work is the novel development and validation of different in situ formed Bi-Sn-film glassy carbon electrodes (BiSnFEs) with changed Bi(III):Sn(II) mass concentration ratios (2:8, 4:6, 6:4, 8:2). These electrodes were formed from solutions with 0.5 mg/L and 1.0 mg/L total Bi(III) and Sn(II) mass concentrations – therefore, eight new electrodes were designed. BiSnFEs were compared with pure Bi-film electrodes (BiFEs) and Sn-film electrodes (SnFEs). It was shown that all electrodes tested demonstrated a high degree of selectivity for Zn(II), Cd(II), and Pb(II) determination, with clearly separated stripping peaks. The widest linear concentration range for Zn(II) determination was obtained at 19.6–413.9 μg/L using an electrode with a Bi(III):Sn(II) ratio of 0.6:0.4 at 0.5 mg/L total mass concentration. For Cd(II) and Pb(II), the widest linear concentration range was measured using pure SnFE at 0.5 mg/L. Moreover, different BiSnFEs significantly increased the method's sensitivity for Zn(II), Cd(II), and Pb(II) determination compared with pure BiFEs and SnFEs. The lowest LOD values were measured using pure BiFEs; however, the LOD values were also relatively low for certain BiSnFEs. An electrode with a Bi(III):Sn(II) ratio of 0.4:0.6 at 0.5 mg/L total mass concentration (i.e. a final solution containing 0.2 mg/L Bi(III) and 0.3 mg/L Sn(II) to form an in situ electrode) demonstrated the greatest accuracy and precision for simultaneous analyte ion determination. Therefore, improved analytical performance can be obtained using BiSnFE compared to pure BiFE. This work also reports for the first time the use of the electrochemical impedance spectroscopy technique to analyse SnFEs and BiSnFEs. The latter analysis showed that the electroanalytical system is under kinetic- and diffusion-controlled processes for SnFEs, whereas BiSnFE is under a kinetic-controlled process. A possible interference effect on the Zn(II), Cd(II), and Pb(II) stripping signals was tested for the presence of Fe(II), As(III), Na(I), K(I), Ca(II), Mg(II), Cu(II), Sb(III), and NO3− ions in the analysed solution. Finally, an analysis of tap water was performed using an electrode with a Bi(III):Sn(II) ratio of 0.4:0.6 at 0.5 mg/L total mass concentration.
Cationic gemini surfactant templated magnetic cubic mesoporous silica and its application in the magnetic dispersive solid phase extraction of endocrine-disrupting compounds from the migrants of food contact materials Microchem. J. (IF 2.746) Pub Date : 2018-11-07 Jiamin Liu, Xiaoyun Ma, Shijuan Zhang, Ting Wu, Hongzhan Liu, Mingyue Xia, Jinmao You
A cationic gemini surfactant templated magnetic cubic mesoporous silica Fe3O4@14-3-14-MCM-48 nanocomposite was successfully synthesized and utilized in the magnetic dispersive solid phase extraction (MDSPE) of nine endocrine-disrupting compounds (EDCs) from the migrants of food contact materials by high performance liquid chromatography with diode array detection (HPLC–DAD). Fe3O4@14-3-14-MCM-48 can interact with EDCs through electrostatic interactions, hydrophobic effect, and hydrogen bonding effect. It showed excellent adsorption performance for EDCs with short alkyl chain phenols, which showed higher hydrophilicity and less retained by normal mesoporous silica with single chain surfactant as template. The parameters affecting MDSPE efficiency were optimized, and the optimum extraction conditions were adsorbent amount, 20 mg; elution solvent, methanol/acetonitrile mixture at 50/50 (v/v); NaCl concentration, 30 g/L; sample pH 5.0. Under the optimized condition, the limits of detection and limits of quantification were in the range of 1.0–2.5 and 2.9–7.5 ng/mL, respectively. Good linearity was observed in the range of 10–200.0 ng/mL with correlation coefficients of >0.997 and the recoveries were in the range of 92.6–102.3%. The developed method was successfully applied to the detection of phenolic EDCs migrants from food contact materials.
Comparison of the sorption capacities of 1,10-phenanthroline and 2,2-bipyridyl complexes with cadmium on activated carbon and graphene oxide Microchem. J. (IF 2.746) Pub Date : 2018-11-15 Barbara Feist
In this study adsorption potential of oxidation activated carbon (ox-AC) and graphene oxide (GO) was investigated. Cd(II) was bound to cationic complexes with 1,10-phenanthroline or 2,2-bipyridyl. The sorbents have been used for the dispersive solid-phase extraction of Cd(II) prior to its inductively coupled plasma optical emission spectrometric or electrothermal atomic absorption spectrometric determination. The influences of the various analytical parameters including pH, eluent type, ligand amount, sample volume and sorption time on the recovery efficiencies of Cd(II) were investigated. The limit of detection for activated carbon - 1,10-phenanthroline and activated carbon - 2,2-bipyridyl were 0.006 and 0.016 ng mL−1, respectively. For graphene oxide with 1,10-phenanthroline and graphene oxide with 2,2-bipyridyl obtained limit of detection were 0.046 and 0.091 ng mL−1, respectively. Maximum adsorption capacities and preconcentration factors were compared. The equilibrium sorption fitted better to the Langmuir isotherm. The method was validated with the certified reference materials ERM-BB186 and SRM 1640a.
Green synthesis of ZnO nanoparticles using Tecoma castanifolia leaf extract: Characterization and evaluation of its antioxidant, bactericidal and anticancer activities Microchem. J. (IF 2.746) Pub Date : 2018-11-14 Govindasamy Sharmila, Marimuthu Thirumarimurugan, Chandrasekaran Muthukumaran
An efficient, facile and green synthesis of zinc oxide nanoparticles (ZnO NPs) using Tecoma castanifolia leaf extract was reported. ZnO NPs was characterized by UV–Vis spectroscopy, TEM, EDX, XRD and FTIR. Phytochemical constituents of T. castanifolia leaf extract were analyzed by GC–MS. UV–Vis absorption showed SPR band at 370–400 nm which confirms the formation of ZnO NPs. TEM analysis exhibits spherical shape with size 70–75 nm and XRD results revealed the hexagonal phase of wurtzite structure. FTIR spectra confirmed the presence of OH, CH, amide-I, II groups, CO bond and metal‑oxygen groups. The presence of bioactive phytochemical constituents in the methanolic extracts of T. castanifolia was identified by GC–MS. An excellent antibacterial activity was observed for both Gram positive and Gram negative bacteria. Results of antioxidant activity showed that increase in concentration of ZnO nanoparticles increases the radical scavenging activity. Anticancer activity with IC50 value as 65 μg/mL which conferred better cytotoxic effects of ZnO NPs on proliferation of A549 cell line. The present study revealed that the pharmacologically active compounds present in the green synthesized ZnO nanoparticles pave the way to lead its effective application in biomedical and nano-drug delivery systems.
Core-shell structured Pt-transition metals nanoparticles supported on activated carbon for direct methanol fuel cells Microchem. J. (IF 2.746) Pub Date : 2018-11-14 K.M. El-Khatib, R.M. Abdel Hameed, R.S. Amin, Amani E. Fetohi
Carbon supported platinum nanoparticles are commonly used as anode catalysts in low temperature fuel cells. Platinum exhibits an enhanced activity towards hydrogen oxidation reaction; however, its performance during low molecular weight alcohols oxidation is poor. Accordingly, this work presents a trial to improve the electrocatalytic performance of platinum-based electrocatalysts by developing core-shell structured M@Pt [M = Zn, Mn or Sn] nanoparticles supported on activated Vulcan XC-72R carbon black [M@Pt/AC]. They were fabricated using ethylene glycol as a reducing agent with the aid of microwave irradiation. The electrocatalytic activity of different M@Pt/AC electrocatalysts for oxidizing methanol molecules in 0.5 M H2SO4 solution was investigated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. These prepared nanomaterials displayed enhanced electrocatalytic behavior towards methanol oxidation reaction. The alcohol oxidation current density was arranged in an ascending order as: Zn@Pt/AC < Mn@Pt/AC < Sn@Pt/AC. Enhanced stability and charge transfer characteristics were also gained at these electrocatalysts especially Sn@Pt/AC to recommend its wide application as an efficient anode material in fuel cells.
Polymerization of graphene oxide with polystyrene: Non-linear isotherms and kinetics studies of anionic dyes Microchem. J. (IF 2.746) Pub Date : 2018-11-13 A. Azizi, E. Moniri, A.H. Hassani, H. Ahmad Panahi, M. Miralinaghi
This study describes the preparation of graphene oxide modified with polystyrene (GO-PS) and its application to Reactive Blue 19 (RB 19), Direct Red 81 (DR 81) and Acid Blue 92 (AB 92) adsorption from aqueous media. The adsorbents were characterized by Brunauer-Emmett-Teller (BET) technique, Fourier transform-infrared resonance (FTIR) spectroscopy, Energy-dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM) analysis. The average pore diameter of graphene oxide (GO) increased from 4.853 nm to 7.051 nm after polymerization. Adsorption capacities of GO-PS for dyes removal were evaluated through batch studies. For Reactive Blue 19, Direct Red 81 and Acid Blue 92 dyes (with an initial dye concentration of 20 mg/L), the adsorption capacities of final adsorbent were found to be 13.13, 19.84 and 15.44 mg/g, respectively. The adsorption equilibrium, isotherm and kinetic non-linear models were tested for the adsorption process and the experimental data were best fitted by the Freundlich isotherm with the high correlation coefficient (R2) of 0.999. The maximum adsorption capacities of dyes were achieved 43.280, 40.663 and 39.067 mg/g for Direct Red 81, Acid Blue 92 and Reactive Blue 19, respectively, by using the Langmuir isotherm model. Moreover, the adsorption kinetics of the dyes on GO-PS was well-described by Elovich (for Reactive Blue 19) and intraparticle diffusion models (for Direct Red 81 and Acid Blue 92). The results of this research revealed that GO-PS is a promising adsorbent for removal of anionic dyes in aqueous solution.
Simultaneous determination of dihydroxybenzene isomers at nitrogen-doped graphene surface using fast Fourier transform square wave voltammetry and multivariate calibration Microchem. J. (IF 2.746) Pub Date : 2018-11-08 Mohammad Reza Moghaddam, Jahan B. Ghasemi, Parviz Norouzi, Foad Salehnia
In this paper, a highly sensitive electrochemical method, which is based on the combination of fast Fourier transform square wave voltammetry and multivariate calibration techniques, was developed for simultaneous determination of dihydroxybenzene positional isomers, including catechol, hydroquinone, and resorcinol, in environmental samples. An electrochemical sensor was constructed by the deposition of nitrogen-doped graphene on a glassy carbon electrode to apply as a new approach for the multicomponent analysis. Partial least squares was applied, as a multivariate calibration method, to deconvolute the highly overlapping electrochemical signals from the analytes. Using the simplex experimental design with the degree of 4, 19 ternary mixture solutions of the cited analytes were prepared in the established linear ranges of the analytes. The developed multivariate model was validated by predicting the concentration of 8 independent solutions. The root mean square error values of validation values were between 0.04230 and 0.06549 μM, respectively. The applicability of the proposed method was checked using water samples (collected from both the surface and waste water) and human urine, and the obtained recovery values were between 89.3 and 107.1%. The limits of detection and relative standard deviations for catechol, hydroquinone, and resorcinol were 0.046, 0.046, and 0.045 μM, and 3.6, 3.4 and 3% (N = 5), respectively.
Superparamagnetic enzyme-graphene oxide magnetic nanocomposite as an environmentally friendly biocatalyst: Synthesis and biodegradation of dye using response surface methodology Microchem. J. (IF 2.746) Pub Date : 2018-11-14 Saeed Kashefi, Seyed Mehdi Borghei, Niyaz Mohammad Mahmoodi
The unique properties of graphene oxide (GO) nanosheets were integrated with the superparamagnetic characteristics of the CuFe2O4 nanoparticles to synthesize the magnetic graphene oxide (MGO), which was chemically modified with 3-amino propyl trimethoxy silane (APTMS) to functionalize the amine group on MGO (MGO-NH2). Afterward, MGO-NH2 was activated with glutaraldehyde (GLU) as a crosslinking agent to synthesize the functionalized MGO (fMGO) and its capability toward covalent Laccase immobilization was investigated. The comprehensive structural analysis using various characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) clearly confirmed the covalent attachment of laccase onto MGO. The response surface methodology (RSM), based on Central Composite Design (CCD), was applied to optimize the immobilized Laccase (nanobiocatalyst)-mediated biodegradation of Direct Red 23 (DR23), as an azo dye, by considering independent variables such as nanobiocatalyst dosage, dye concentration, and pH. The optimal conditions to obtain the maximum decolorization yield (95.33%) were nanobiocatalyst dosage = 290.23 mg/L, dye concentration = 19.60 mg/L, and pH = 4.23. The obtained correlation coefficient and the adjusted one of 0.9651 and 0.9336, respectively, imply the nice model fitness. Therefore, structural characterization along with the experimental decolorization results introduced the synthesized superparamagnetic GO as an environmentally friendly nanobiocatalyst for effective decolorization purposes.
An immunological determination of somatostatin in pharmaceutical by sandwich ELISA based on IgY and polyclonal antibody Microchem. J. (IF 2.746) Pub Date : 2018-11-11 Yingshan Chen, Yuxin Liang, Rui Lv, Nana Xia, Tianjian Xue, Suqing Zhao
A sensitive and specific enzyme-linked immunosorbent assay (ELISA) for the detection of Somatostatin based on double antibody sandwich method was studied in this paper. The Somatostatin specific Yolk antibody (IgY) and polyclonal antibody were available to Somatostatin-conjugated KLH immunized rabbits and chickens used to construct the sandwich ELISA for the measurement of Somatostatin. The limit of detection was 0.1 μg/mL and the half maximal inhibitory concentration (IC50) was 0.859 μg/mL. The method developed in the study showed no evident cross-reactivity with other similar analogs. The recoveries of Somatostatin spiked mannitols were in the range of 98.45% to 103.90% with intra- and inter-day coefficient of variants (CVs) <8.71% and 4.60% respectively. The detection standard curve of Somatostatin exhibited a good linearity (R2 = 0.9931, n = 3). Therefore, the methods could be selectively used for rapid screening of Somatostatin in pharmaceutical.
A facile stage for Cu2+ ions detection by formation and aggregation of Cu nanoclusters Microchem. J. (IF 2.746) Pub Date : 2018-11-14 Zhi Shen, Cheng Zhang, Xinling Yu, Jian Li, Bianhua Liu, Zhongping Zhang
In recent years, copper nanoclusters (Cu NCs) have attracted a great deal of research interests, because the fluorescence intensity will be significantly enhanced after they aggregate, which makes them an ideal material for constructing chemical sensors. The current Cu NCs based sensor researches focus mainly on the control of surface modification and aggregation conditions. Herein, we report a method for direct detection of Cu2+ ions through in situ cluster formation and aggregation. Glutathione was used as both reducing agent and stabilizing agent, while tetrahydrofuran as the poor solvent. When the analyte of Cu2+ ions were added to the mixed solution, they were reduced and aggregated to generate bright orange emission. The method is easy to operate and the reaction complete within 2 min. The detection limit for Cu2+ ions is as low as 0.17 μM. Based on these findings, we successfully achieved the determination of copper content in naturally occurring mineral. Therefore, the method reported here provides a convenient and sensitive way to perform qualitative analysis of Cu2+ ions.
Mixed-mode solid phase extraction combined with LC-MS/MS for determination of empagliflozin and linagliptin in human plasma Microchem. J. (IF 2.746) Pub Date : 2018-11-14 Priyanka A. Shah, Pranav S. Shrivastav, Archana George
A selective, sensitive, precise and accurate liquid chromatography-tandem mass spectrometry method was developed and validated for the concurrent determination of antidiabetic drugs, empagliflozin and linagliptin in human plasma. Sample preparation was tested on several reversed-phase solid-phase extraction (SPE) sorbents with different chemistries like hydrophilic-lipophilic balance (Oasis HLB), mixed-mode cation exchange (Oasis MCX) and weak-cation exchange (Oasis WCX). SPE conditions like sample pH, washing and elution solvents were suitably optimized. Best results were obtained using Oasis MCX cartridges in terms of extraction recovery (78–88%) and matrix effects (~3.0%) for both the analytes. Chromatographic conditions for the separation of analytes and their labeled internal standards (ISs) were established on XSelect HSS Cyano (50 × 2.1 mm, 3.5 μm) column using 2 mM ammonium acetate buffer and acetonitrile as the mobile phase. Detection of analytes was achieved using electrospray ionization in the positive mode. For quantitative analysis, multiple reaction monitoring transitions were m/z 451.3 → 71.1 for empagliflozin and m/z 473.2 → 420.2 for linagliptin. Standard curve concentrations were validated in the range of 1.50–1500 ng/mL for empagliflozin and 0.015–15.0 ng/mL for linagliptin. The intra-batch and inter-batch precision (% CV) was <3.7 for both the drugs. The stability of the analytes established under different storage conditions was found to be appropriate for routine laboratory practices. The validated method was used to study the pharmacokinetics of the drugs using a single oral dose of fixed-dose combination tablet consisting of 25 mg empagliflozin and 5 mg linagliptin in healthy subjects.
Optimized poly(amidoamine) coated magnetic nanoparticles as adsorbent for the removal of nonylphenol from water Microchem. J. (IF 2.746) Pub Date : 2018-11-11 Vahid Khatibikamal, Homayon Ahmad Panahi, Ali Torabian, Majid Baghdadi
In this study, different generation of poly(amidoamine) (PAMAM) coated magnetic iron oxide nanoparticles were successfully synthesized via divergent growth approach of dendrimer for the removal of nonylphenol (NP) from water. The characterization of synthesized nanoparticles was performed by XRD, FTIR, TEM, FE-SEM, EPX, and VSM. The results suggested that there is a direct correlation between the number of dendrimer generation and its adsorption capacity; however, the rising generation >10 could not enhance NP removal efficiency, significantly. The 10th generation of PAMAM-MNP was modified by 4-aminophenol (MNP-G10-pAP) to enhance its adsorption capacity. The kinetic studies were performed after the determination of optimal adsorption conditions (pH, 7; Detention time, 60 min). It was found that Dubinin–Radushkevich (D–R) isotherm and pseudo-second order model are perfectly stimulated the adsorption behavior and kinetic rate of NP uptake. Furthermore, the NP removal efficiencies of 70, 67, 63 and 65% were observed for distilled water, drinking water, well water and treated wastewater, respectively. Finally, it was revealed that the synthesized product had acceptable reusability in eight times and NP removal efficiency decreased by just 15%.
Shaker-assisted liquid-liquid microextraction of methylene blue using deep eutectic solvent followed by back-extraction and spectrophotometric determination Microchem. J. (IF 2.746) Pub Date : 2018-11-04 Raheleh Ahmadi, Ghasem Kazemi, Amir M. Ramezani, Afsaneh Safavi
This research describes the spectrophotometric determination of methylene blue (MB) after shaker-assisted liquid-liquid microextraction combined with back-extraction (SALLME-BE). A hydrophobic deep eutectic solvent (DES) was used for extraction of MB from alkaline solutions (0.5 M NaOH). Then, the extracted dye was back-extracted into a hydrochloric acid solution (2 M). Decanoic acid and methyltrioctylammonium bromide were used, respectively as hydrogen bond donor and hydrogen bond acceptor constituents of the hydrophobic DES. The calibration graph was linear in the range of 2–170 ng mL−1. The recovery analysis of wastewater and river water samples verified that this method is practical for environmental monitoring.
Investigating Janus morphology development of poly(acrylic acid)/poly(2‑(dimethylamino)ethyl methacrylate) composite particles: An experimental study and mathematical modeling of DOX release Microchem. J. (IF 2.746) Pub Date : 2018-11-10 Mehrab Fallahi-Samberan, Mehdi Salami-Kalajahi, Elham Dehghani, Farhang Abbasi
Distillation precipitation polymerization (DPP) of acrylic acid were studied in the presence of two different crosslinkers including N,N′‑methylenebis(acrylamide) (MBA) and ethylene glycol dimethacrylate (EGDAMA). After morphological study of the resultant particles, the best morphological sample was selected as seed for seeded emulsion polymerization (SEP). Composite particles were fabricated by SEP of 2‑(dimethylamino)ethyl methacrylate (DMAEMA) and MBA as crosslinked. Patchy particles, polyhedral core-shell particles, cauliflower-like particles, core-shell particles with porous shell, dumbbell-like particles and core-shell particles were synthesized by different strategies. The size, structure and surface morphology of synthesized particles were characterized using DLS and FE-SEM techniques. Morphology development and mechanism of shell formation such as nucleation and growth of lobes on seed particles were investigated. Finally, well-defined morphologies have been used as doxorubicin hydrochloride (DOX) anti-cancer drug carriers and DOX release kinetics has been discussed by different mathematical models.
High-performance removal of diazinon pesticide from water using multi-walled carbon nanotubes Microchem. J. (IF 2.746) Pub Date : 2018-10-25 Mohammad Hadi Dehghani, Saeideh Kamalian, Mansoreh Shayeghi, Mahmood Yousefi, Zoha Heidarinejad, Shilpi Agarwal, Vinod Kumar Gupta
Diazinon is one of the most commonly used organophosphorus pesticides in agricultural activities, and its access to groundwater and surface waters damages the animal and plant environments. This study aimed to evaluate the applicability of the adsorption process for the removal of organophosphorus diazinon pesticide from water using multi-wall carbon nanotubes. Specifications of multi-walled carbon nanotubes were determined using FTIR, SEM, TEM and BET technologies. The effects of different parameters of pH (4 and 7), contact time (1–15 min), pesticide concentration (0.3, 0.5 and 1 mg/L) and multi-walled carbon nanotubes' dose (0.1 and 0.3 g/L) were evaluated on the process of removing diazinon by multi-walled carbon nanotubes. Based on the experimental data obtained in this study, maximum removal of diazinon (100%) from water by multi-wall carbon nanotubes are the initial concentration of diazinon (0.3 mg/L), 0.1 g/L concentration of nano-adsorbent at both pH of 4 and 7 at the contact time of 15 min. The results of the study showed that multi-wall carbon nanotubes can be used as effective and high efficient for complete removal of diazinon pesticides from aqueous solutions.
Defluoridation in fixed bed column filled with Zr(IV)-loaded garlic peel Microchem. J. (IF 2.746) Pub Date : 2018-11-05 Yangzhong Zhang, Lue Xiong, Yifan Xiu, Kai Huang
Zirconium loaded garlic peel (GP) is an efficient and cheap material for defluoridation of groundwater, while its column run is seldom studied. The purpose of this study was to evaluate the performance of Zr(IV)-loaded garlic peel in the removal of fluoride from a continuous fixed bed column in order to provide guidance for the design and operation of the column reactor. The effects of Zr(IV) ion loading concentration, initial pH, initial fluoride concentration, flow rate and bed depth on the fluorine adsorption performance were investigated. The Thomas model and the bed depth service time model were found to agree well with the experimental data. The practical groundwater samples containing excessive fluoride collected from the Banzhuang Village, Dongguang County, Cangzhou City, Hebei Province, were used to examine the effectiveness in the fixed bed column, and around 1.2 liter clean groundwater was produced to reach the national standard of China (1.0 mg/L) through a 0.5 gram Zr(IV)-GP column, meaning that 2.4 m3 cleaning water can be obtained based on 1 kg Zr(IV)-GP adsorbent. Elution of adsorbed fluoride can regenerate the Zr(IV)-GP column by using 1 M NaOH, and at least 3 cycles were done to find that a little worsening of adsorption capability. In a word, the cleaning of fluoride-bearing groundwater with a Zr(IV)-GP fixed bed column is expected to be applicable on large scale. The adsorbent is inexpensive, and the cost of 1 kg of adsorbent does not exceed $0.50.
Separation of silver ions and silver nanoparticles by silica based-solid phase extraction prior to ICP-OES determination Microchem. J. (IF 2.746) Pub Date : 2018-11-06 Pimpimon Anekthirakun, Apichat Imyim
Silver ions Ag(I) and silver nanoparticles (AgNPs) in solution could be separated using aminopropylsilica (SiAP) as a solid adsorbent prior to a determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). The extraction of both silver species from a binary mixture occurred rapidly within 5 min at the optimal pH 3. The adsorption behavior was illustrated by the Langmuir model at 298 K and the maximum adsorption capacity of SiAP for Ag(I) ions and AgNPs was 52.91 and 34.01 mg g−1, respectively. The selective desorption of Ag(I) ions and AgNPs was successful using thiourea. The proposed method was applied for the determination of silver species in household products.
Syntheses and characterization of copper metal complexes prepared from chalcone derivatives Microchem. J. (IF 2.746) Pub Date : 2018-11-07 Vikas Vilas Borge, R.M. Patil
The present paper deals with the Syntheses and Characterization of metal complexes of some substituted chalcones of 2-Hydroxy-4,5-dimethylacetophenone with aromatic aldehyde like benzaldehyde, 4-hydroxybenzaldehyde, 4-Nitrobenzaldehyde and 3-Chlorobenzaldehyde. The resulting compounds were characterized by elemental analysis, conductivity measurement, IR spectra, ESR spectra, UV-Visible and TGA analysis. The chalcones acts as bidentate ligand and coordinating through deprotonated oxygen and ketonic oxygen atoms.
Application of bioactive cyclic oligosaccharide on the detection of doxorubicin hydrochloride in unprocessed human plasma sample: A new platform towards efficient chemotherapy Microchem. J. (IF 2.746) Pub Date : 2018-11-06 Parastoo Mohammad Alizadeh, Mohammad Hasanzadeh, Jafar Soleymani, Jalil Vaez Gharamaleki, Abolghasem Jouyban
In this study, a novel nano-composite based on poly‑taurine/beta‑cyclodextrin and graphene quantum dot used for the modification of gold electrode by simple electrodeposition approach. The prepared interface was applied for the sensing of doxorubicin hydrochloride (DOX) in human plasma samples without any pretreatment procedure. The synergistic influence of poly-taurine, beta-cyclodextrin, and graphene quantum dot not only remarkably enhances electroactivity, but also speeds up the electron shift between DOX and the electrode substrates. Cyclic voltammetry results indicated that the DOX is oxidized via two electrons and two protons process at the optimum pH = 4 using poly-taurine/beta-cyclodextrin and graphene quantum dots thin film modified gold electrode. More momentously electrostatic repulsion takes place between the prepared polymeric film and DOX resulting in the signal amplification on oxidation of this drug and lowering its overpotential and thereby sensitive and selective detection of DOX in real samples. The apparent electron transfer rate constant and transfer coefficients were determined by cyclic voltammetry. Using differential-pulse voltammetric (DPV) technique sensitive determination of DOX in human plasma samples was performed with wide dynamic range and good limit of detection.
Study of thermospray and evaporation effects in a flame-on-a-chip Microchem. J. (IF 2.746) Pub Date : 2018-10-31 Arpad Kiss, Adam Kecskemeti, Attila Gaspar
In the present work, a simple thermospray sample introduction applied in the recently developed μFAES system (where a microburner and flame were created on a microchip (flame-on-a-chip)) was extended with a process based on combined effects of thermospray and evaporation of the formed solid salts. In the used microfluidic system, the mechanisms of the thermospray and evaporation exhibit interesting and new features, which can be utilized in atomic spectroscopy. The effects of several parameters (like flow rates, sample volume and inner diameter of the thermospray capillary) of the sample introduction were investigated.
Oxadiazole-based ‘on-off’ fluorescence chemosensor for rapid recognition and detection of Fe2+ and Fe3+ in aqueous solution and in living cells Microchem. J. (IF 2.746) Pub Date : 2018-11-06 Xue Gong, Heyang Zhang, Nan Jiang, Lin Wang, Guang Wang
Voltammetric method for simultaneous determination of ascorbic acid, paracetamol and guaifenesin using a sequential experimentation strategy Microchem. J. (IF 2.746) Pub Date : 2018-11-06 Hassan A.M. Hendawy, Ahmed M. Ibrahim, Wafaa S. Hassan, Abdalla Shalaby, Heba M. El-sayed
Cold is a leading cause of school and work absenteeism. Most cold over-the-counter medicines (OTC) contain paracetamol (PA), guaifenesin (GU) and other active ingredients. Ascorbic acid (AS) in pharmaceutical preparations is designed for preventing and treating respiratory viral infections. Thus, we report a robust voltammetric method for simultaneous determination of AS, PA and GU in their effervescent dosage form. The advantages of nanotechnology and chemometrics were combined to enhance the performance of electroanalysis. Fractional factorial design (FrFD) and dual response surface method (DRSM) were sequentially conducted. The method was validated in agreement with ICH guidelines; it showed accuracy over the concentration range of 11.3–108.9, 14.6–140.3, 4.6–43.9 μg ml−1 for AS, PA and GU, respectively. Based on findings, a robust and not time-consuming procedure was applied.
Low cost thiol-functionalized mesoporous silica, KIT-6-SH, as a useful adsorbent for cadmium ions removal: A study on the adsorption isotherms and kinetics of KIT-6-SH Microchem. J. (IF 2.746) Pub Date : 2018-11-05 Saman Bagheri, Mostafa M. Amini, Mohammad Behbahani, Ghazal Rabiee
In this study, we have prepared and characterized 3‑(trimethoxysilyl)‑1‑propanethiol functionalized mesoporous silica, KIT-6-SH, then investigated its efficacy in the sense of cadmium removal. KIT-6-SH was characterized by FT-IR spectroscopy, TGA, X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The obliteration of cadmium ions by KIT-6-SH was found to be mainly governed by surface adsorption. The elimination of cadmium ions from aqueous solutions was conducted using a batch method. Factors including the initial metal ion concentration, pH, and contact time were determined to be influential parameters on the sorption process. The sorption isotherm data were clearly described by the Langmuir model and maximum adsorption capacity for KIT-6-SH was 85 mg g−1. Moreover, a pseudo-second-order kinetic model was found to govern the sorption kinetics. According to these findings, it can be concluded that KIT-6-SH is well suited for the efficient and selective removal of cadmium ions from aqueous solutions.
The application of non-destructive techniques for the study of corrosion patinas of ten Roman silver coins: The case of the medieval Grosso Romanino Microchem. J. (IF 2.746) Pub Date : 2018-11-02 Lucilla Fabrizi, Francesca Di Turo, Laura Medeghini, Melania Di Fazio, Fiorenzo Catalli, Caterina De Vito
This work focuses on the study of ten Grosso Romanino, a silver medieval coin, minted in Rome during the 13th century CE. As the coinage of this denomination occurred during a tumultuous period of the history of Rome, the official documentation from Mint was lost. For this reason, archaeometric investigations were necessary to have an overall knowledge of the Grosso Romanino. This work represents the first attempt of archaeometric study performed on this interesting denomination. The coins were characterized by a combination of non-destructive techniques, i.e., X-ray diffraction (XRD), Scanning Electron Microscopy (SEM-EDAX), micro-Raman spectroscopy and Voltammetry of Microparticles (VIMP), aiming to investigate the external surface and its microstructure and to explore the nature of the alloy and corrosion products. The results show an Ag- rich alloy with minor amount of copper (2.1–3.1 wt%), lead (0.7–3.2 wt%) and other elements. Moreover, the rare corrosion products on the surfaces indicate the presence of a random distributed patina composed by oxides, sulfides and chlorides.
Simultaneous separation of arsenic and cadmium from interfering salt matrix of multivitamin/mineral supplements by sequential coprecipitation and determination by inductively coupled plasma mass spectrometry Microchem. J. (IF 2.746) Pub Date : 2018-11-05 Ermira Begu, Brittney Snell, Zikri Arslan
Multivitamin/mineral (MVM) supplements possess highly saline matrix which, unless eliminated, precludes accurate determination of trace amounts of toxic metal impurities by inductively coupled plasma mass spectrometry (ICP-MS). Multi-step separations (up to four-steps) are described in literature; often for single element determinations due to the difficulties in removing the matrix components. In this study, we developed a three-step sequential coprecipitation procedure for simultaneous separation of As and Cd impurities from MVM supplements for determination by ICP-MS. The procedure provided effective elimination of salt matrix, including Ca, Mg and KCl along with the interfering molybdenum (Mo) and tin (Sn) from MVM solutions. KCl, Mo and Sn were reduced by two-step Mg(OH)2 coprecipitation to about 34 μg mL−1 K (ca. 31 μg mL−1 Cl) and 0.4 μg mL−1 Mo. Levels of Sn and Na were not significant. A third coprecipitation of the resulting MVM solution with HF + NH4OH mixture precipitated virtually all Ca and Mg to as low as 1 and 10 μg mL−1, respectively. The recoveries for As and Cd in the spiked MVM solutions were about 96% and 95%, respectively. The accuracy of the method was validated with analysis of multivitamin/multielement tablets certified reference material (SRM 3280). Experimental values were 112 ± 37 ng g−1 for 75As, and 76 ± 5, 79 ± 5, and 78 ± 7 ng g−1 for 110Cd, 111Cd and 114Cd isotopes, respectively, that were not significantly different from the certified values of As (132 ± 44 ng g−1) and Cd (80.2 ± 0.9 ng g−1) at 95% confidence level. Several commercially available MVM supplements were analyzed with the procedure. Mean As levels measured in the tablets varied between 24 and 128 ng g−1 and that for Cd were between 28 and 125 ng g−1 indicating total amount of As or Cd ingested per serving size were below the safe daily exposure limits. In addition, the results obtained for As and Cd with the procedure were lower in comparison to the values reported in literature indicating that ICP-MS analysis of complex MVM supplements could be prone to higher risks of inaccuracy without removal of interfering matrix.
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