The future of liquid chromatographic separations should include post column derivatisations: A discussion view point based on the perspective for the analysis of vitamin D Microchem. J. (IF 3.034) Pub Date : 2018-02-01 Andrew Jones, Visalini Nair-Shalliker, Gary R. Dennis, R. Andrew Shalliker
The coupling of high performance liquid chromatography (HPLC) with post column derivatisation (HPLC-PCD) will increase the sensitivity of an instrument to the target molecule, improve specificity by selective derivatisation to remove potential interferences from the matrix, and be cost-effective; all these factors may well prove that PCD is an alternative to existing techniques for routine analysis. Calcidiol (25(OH)D) concentrations are used in the determination of vitamin D deficiency in humans, and there is growing interest and demand in its analysis with some controversy surrounding the sensitivity and specificity of its detection. 25(OH)D analysis is currently performed using either competitive binding assays or HPLC analysis, coupled with detection by a variety of means, such as, UV–Vis absorption, electrochemical or mass spectroscopy (MS) detection. HPLC coupled with MS (HPLC-MS) detection is the gold standard for 25(OH)D analysis due to its sensitivity and selectivity compared to all other techniques, however, its utility is limited by its high cost. This article reviews the current status of HPLC based techniques in the detection of 25(OH)D (and its metabolites), and further explores the use of HPLC-PCD.
Comparison of fit for a future purpose concept based on tolerance interval and ISO 11352 approaches to predict the quantitative performances and routine uncertainty of an ICP-MS method for the determination of 21 elements in drinking water Microchem. J. (IF 3.034) Pub Date : 2018-01-31 R. El Hajji, A. Boussetta, B. Aznag, F. Agdouz, B. Ihssane, O.A. Hamedane, T. Saffaj
This article outlines the validation results of an analytical method for the dosage at the same time twenty-one trace and ultra-trace elements - Li, Be, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Sb, Pb, Ag and Hg (using gold as a mercury stabilizer) - by ICP-MS in drinking water samples. A new validation methodology based on the expanded uncertainty profiles was exploited to select the best suitable calibration model, to assess the method accuracy within well-defined acceptability limits and to determine the limits of quantification as well as the working range. By means of an innovative formula based on the uncertainty concept, the validation study was completed and supported by the investigation of the risk profiles of various acceptable regression models with the aim of minimizing the risk of either accepting an invalid method or refusing a valid method. On the other hand, a new way of calculating the uncertainty of analytical results derived from β-content γ-confidence, tolerance interval as a complement to the top-down approaches proposed to date was described. The uncertainty estimates obtained by this proposal from validation data were compared via F-test with those arising from the ISO-11352 norm. In the light of this comparison, it can be concluded that our strategy makes it possible to approximate perfectly the routine uncertainty.
Metsulfuron-methyl determination in environmental samples by solid surface fluorescence Microchem. J. (IF 3.034) Pub Date : 2018-02-21 Magdalena Alesso, César A. Almeida, María C. Talio, Liliana P. Fernández
A new environmental friendly methodology for metsulfuron-methyl quantification based on the fluorescent signal enhancement of rhodamine B dye has been developed. A cationic surfactant (cetyltrimethylammonium bromide, CTAB) and an anionic one (sodium dodecylsulfate) were employed to preconcentrate the herbicide using a coacervation phenomenon, in sodium borate buffer medium (pH 9.2). The coacervate phase was collected on a nylon membrane (0.45 μm) and the solid surface fluorescence signal was determined (λexc = 515 nm, λem = 565 nm). Experimental variables that influence on preconcentration step and fluorimetric sensitivity have been studied and optimized using response surface methodology. Under optimal working conditions, a LOD of 0.17 μg L−1 and a LOQ 0.53 μg L−1 was obtained. The zeroth order regression calibration was linear from 0.53 to 5.00 μg L−1. The method showed adequate sensitivity and selectivity, and was applied to the determination of trace amounts of metsulfuron-methyl in environmental water samples. The proposed methodology implies an alternative to traditional techniques for metsulfuron-methyl monitoring using an accessible instrument in control laboratories, representing a contribution in the toxicological and environmental areas for the monitoring of MSM in environmental samples, in agreement with the Green Chemistry.
Protective effect of linseed oil varnish on archaeological wood treated with alum Microchem. J. (IF 3.034) Pub Date : 2018-02-12 Jeannette Jacqueline Łucejko, Jacopo La Nasa, Caitlin M.A. McQueen, Susan Braovac, Maria Perla Colombini, Francesca Modugno
The Viking Age wooden artefacts recovered in the early 1900s from the Oseberg mound (Norway) and treated with alum, are today highly degraded. This is due to the effects of the alum-treatment and the reactivity of alum and alum-derived salts . Some of the artefacts from the Oseberg collection that were treated with alum were also coated with a drying oil: boiled linseed oil. These artefacts appear to be better preserved with respect to those not treated with linseed oil. In order to assess the effect of linseed oil on wood preservation, an alum-treated archaeological wood fragment from the Oseberg collection treated with linseed oil was investigated by three analytical techniques: gas chromatography coupled with mass spectrometry (GC/MS), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-ToF). These techniques provided important information on the molecular composition and state of preservation of both archaeological wood and aged linseed oil. Py(HMDS)-GC/MS was applied to assess the state of preservation of the main wood components, lignin and polysaccharides, in the presence of linseed oil and alum treatments. GC/MS and HPLC-ESI-Q-ToF were used to perform lipid characterisation and to investigate the lipid degradation and oxidation processes. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and elemental analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) were performed to give information on the corresponding inorganic components, particularly the composition and distribution of the alum. Samples taken at different depths from the surface of the archaeological wood fragment were analysed and compared. The results showed that, although the wood was highly depleted of carbohydrates, it was better preserved than previously analysed Oseberg artefacts not treated with linseed oil. Results from GC/MS and HPLC-ESI-Q-ToF suggested that the linseed oil played a mitigating role in terms of wood degradation. The behaviour of the lipid material, which was more oxidized on the wood surface than in the core, was the opposite to that usually encountered in archaeological wood, suggesting a selective oxidation of the linseed oil. This unusual pattern of wood degradation was not mirrored by the inorganic components: alum was found to be more abundant at the surface of the fragment than at depth, as would be expected, but no decomposition products were found. However, the alum appeared to mainly consist of ammonium salt, rather than the potassium alum documented as the treatment material for the Oseberg artefacts.
An improved and miniaturized analytical strategy based on μ-QuEChERS for isolation of polyphenols. A powerful approach for quality control of baby foods Microchem. J. (IF 3.034) Pub Date : 2018-02-22 Natalia Casado, Rosa Perestrelo, Catarina L. Silva, Isabel Sierra, José S. Câmara
An improved and miniaturized quick, easy, cheap, effective, rugged and safe (μ-QuEChERS) strategy combined with ultra-high pressure liquid chromatography coupled to a photodiode array detection system (UHPLC-PDA) was developed and optimized for the determination of twelve polyphenols in different baby foods samples. The proposed analytical approach proved to be highly cost-effective and environmentally friendly, since it showed good extraction efficiency using few amounts of sample (0.3 g), organic solvents (1000 μL), clean-up sorbents (87.5 mg) and partitioning salts (0.2 g), producing minimal waste disposal and reducing analysis time. Method performance was validated in terms of selectivity, linearity, limits of detection and quantification, matrix effects, precision and accuracy using different baby food matrices according to their composition. The overall average recoveries ranged from 71 to 100% with relative standard deviations lower than 6% (n = 18). The method was successfully applied to commercial baby food samples (including pureed solids, juices and porridges), and their total phenolic content (TPC) and antioxidant capacity (RSA) were also investigated. Results allowed characterizing the abundance of the selected polyphenols in the samples, and the highest RSA and TPC were found in the fruit-based baby foods. Thus, this work represents a first approach to determine the nutritional quality of these products.
Validity of the best practice in splitting data for hold-out validation strategy as performed on the ink strokes in the context of forensic science Microchem. J. (IF 3.034) Pub Date : 2018-02-14 Loong Chuen Lee, Choong-Yeun Liong, Abdul Aziz Jemain
The self-absorption phenomenon in quantitative Raman spectroscopy and how to correct its effects Microchem. J. (IF 3.034) Pub Date : 2018-02-15 L.M. Uriarte, L.J. Bonales, J. Dubessy, A. Lobato, V.G. Baonza, M. Cáceres
When the wavelength of the Raman scattered light coincides with the absorption spectrum of the sample, a phenomenon known as Raman self-absorption occurs. If the absorption wavelength range matches completely with the Raman wavenumber range for a given excitation line (high absorption), this process causes spectra with poor signal-to-noise-ratio, making the acquisition nearly impossible. When the absorption of the sample and the Raman scattered are partially coincident (low absorption), smaller modifications in the band-profile of the Raman spectrum are expected difficult to be detected. If a different excitation wavelength is available in order to avoid or minimize this phenomenon, a correction method is customary. The correction methods developed so far in quantitative analysis are still very complex and require the knowledge of several sampling parameters. In this work, we present a very simple but reliable method based on the Beer-Lambert law to correct low self-absorption effects. This method uses simple concepts, a straightforward methodology and the concentration of the Raman active component in the liquid matrix is the only parameter required to perform the correction. This method may be extremely useful in different fields in which Raman spectroscopy is used to obtain molecular and structural information from a band profile analysis. As an example, the method is applied here to successfully correct the Raman spectra of different CuSO4 aqueous solutions excited at 532 nm.
Multivariate cathodic square wave stripping voltammetry optimization for nitro group compounds determination using antimony film electrodes Microchem. J. (IF 3.034) Pub Date : 2018-02-24 Jessica Moreno Betancourth, Mariela Cuellar, Patricia I. Ortiz, Valeria Pfaffen
The main goal of this paper is the optimization of the square wave voltammetric response of antimony film electrode (SbFE) to determine reducible nitro groups using response surface methodology (RSM). The SbFE was prepared on a glassy carbon electrode (GCE) while cathodic stripping square wave voltammetry (CSSWV) was used as detection technique. In this study, the optimization process of solution pH and 4,6-dinitro-o-cresol (DNOC) accumulation time was carried out using a Central Composite Design (CCD) while a Box–Behnken Design for SWV instrumental variables optimization. The two reduction current peaks were used as dependent variable to evaluate the performance of the system. For solution pH and DNOC accumulation time the optimization process considered only reduction current peak, while for SWV instrumental parameters (step, amplitude and frequency) both the relationship between current peak and standard deviation with the different factors were analysed, finally both designs were quantitatively described by a multivariate regression model through the RSM. Furthermore, the optimal parameter combinations were obtained by maximizing the reduction current peak and minimizing standard deviation within the studied experimental range. Under the optimal parameter combination, a linear calibration curve ranged from (1.0 to 15) × 10−6 mol L−1 with a detection limit of 1.12 × 10−6 mol L−1 was obtained. The proposed analytical procedure was further applied to detect DNOC in natural water samples with satisfactory results.
Colours and pigments in late ukiyo-e art works: A preliminary non-invasive study of Japanese woodblock prints to interpret hyperspectral images using in-situ point-by-point diffuse reflectance spectroscopy Microchem. J. (IF 3.034) Pub Date : 2018-02-17 Josefina Pérez-Arantegui, David Rupérez, David Almazán, Nerea Díez-de-Pinos
Dyes and pigments have been used in traditional Japanese woodblock printings in the ukiyo-e style for several centuries. However, the possible introduction of new European pigments and the extraordinary quality of the works of the later period led to take a keen interest in the analytical study of these ukiyo-e prints manufactured at the end of the 19th century. The present research discusses the analytical results of the series Bijin jūni kagetsu (“Beauties in the Twelve Months”) by Shuntei, dated in 1898–1899. Due to the characteristics of this type of artworks, diffuse reflectance spectroscopy (DRS) has been chosen as a portable, non-invasive analytical technique to identify pigments and colorants used in the woodblock prints. The analytical possibilities offered by the in-situ point-by-point DRS as a preliminary tool to better interpret hyperspectral imaging (HSI) data were highlighted. Reflectance spectra of more than 190 points sampled throughout the artwork were recorded between 360 and 740 nm, and characterised. Throughout an statistical classification of the spectral data using unsupervised pattern recognition methods, twenty-two different colour composition was confirmed. These groups of reflectance spectra were then identified according the presence of characteristic maxima, minima and inflection points in every spectrum. Some micro-samples extracted from the pigments still remained in a woodblock (used for a 20th century print) were analysed by FESEM-EDS to better interpret some reflectance spectra. Traditional Japanese pigments (like vermilion, red lead, and indigo) and synthetic materials introduced in the 18th and 19th centuries (Prussian blue, synthetic arsenic sulphides, eosin, and methyl violet or crystal violet) were identified in the Shuntei's series colours, together with some mixtures of pigments to prepare blue, green, orange and purple. Based on these twenty-two reflectance patterns, the point-by-point spectra make easier the task of interpreting the very complex HSI data, and reduce the time of treatment and interpretation required by HSI.
Effect of the duty ratio on FFT power spectrum of the emission signal excited by square-wave-pulsed glow discharge plasma Microchem. J. (IF 3.034) Pub Date : 2018-02-21 Osamu Miura, Kikuyasu Sasaki, Kazuaki Wagatsuma
An advanced data-processing method using a fast Fourier transform (FFT) analyzer, associated with a modulation of DC voltage applied to a plasma excitation source, is suggested in glow discharge optical emission spectrometry (GD-OES). A pulsation of the DC voltage can be employed effectively for analysis of several specified samples, such as a ultra-thin layer to suppress the sputtering rate; however, it might worsen the analytical performance due to a decrease in the emission intensity. The FFT analyzer has an ability to disperse electronic signals by frequency to yield a power spectrum, and it is thus employed to select the component at a particular frequency. In pulsed GD-OES, data analysis based on FFT algorism enabled the signal component of an analyte emission line to be separated at a pulse frequency from the overall emission signal having any other frequencies, when the pulsed discharge voltage could control the sampling and excitation processes of the analyte in the plasma. The power spectrum of a Cu I emission line strongly depended on the duty ratio of the pulsed DC voltage, because each signal component at higher-order overtone frequencies contributed to the spectrum in a different manner. At a duty ratio of 20%, a summation of the FFT components from the fundamental frequency to higher-order harmonic frequencies could be effective to obtain larger signal intensities with smaller variances. The FFT component of the Cu I signal summed up to the eighth harmonic frequency was 3.8-times as large as the component of the fundamental frequency, whereas the RSD was improved from 2.32% to 0.20%.
Preliminary results on the influence of car characteristics on their gases emissions using gas sensors Microchem. J. (IF 3.034) Pub Date : 2018-02-21 M. Kacem, K. Zaghdoudi, A. Morales-Rubio, M. de la Guardia
A method, based on the use of monitoring portable sensors, has been successfully employed for the determination of the composition of car exhausts from 11 diesel and 5 gasoline cars. These emissions include nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2) and volatile organic compounds (VOCs). The measures were taken in different places where each car was parked. In this study it has been tried to correlate the emitted gases with some of the car characteristics, such as the power (varied from 68 to 143 HP), the number of kilometers traveled and the age of the car (between 2 and 19 years). Results found show a significant variation of the emission values, which range between 490 and 3350 ppm for CO2, from 0.1 to 40.3 ppm for CO and between 0.13 and 32.25 mg/m3 for VOCs. In the case of NO2 emissions, the highest measured level was 4.66 mg/m3. Moreover, measurements of human breath, before starting up and turning off the car, were used to evaluate the impact of vehicle emissions on the human health. It was found exposition levels which indeed the effects of exhausts on the quality of operator air lungs.
Soil forensics: A spectroscopic examination of trace evidence Microchem. J. (IF 3.034) Pub Date : 2018-02-19 Rohini Chauhan, Raj Kumar, Vishal Sharma
Among various trace evidence, the soil is very crucial evidence because it can link the suspect with the crime and crime with its geographical region. Based on this hypothesis, the aim of present research is to characterize, differentiate and classify the soil samples collected from various geological regions of northwestern India via using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy combined with chemometrics. The organic and inorganic parts of surface and depth soil samples are successfully characterized. Sieving and heating of soil in a muffle furnace (650 °C) affect the spectral features considerably. The differentiation of soil samples is done by utilizing two approaches i.e. qualitative analysis and multivariate analysis. Both approaches provide a high discriminating power (i.e. qualitative analysis, surface = 99.35%, depth = 97.38%, and multivariate analysis, surface = 100%, depth = 100%). A classification model based on canonical discriminant function analysis is also built for grouping of soil to its particular geographical region. The developed model provides 100% correct classification of soil samples after the leave-one-out cross-validation. Therefore, the current study provides useful methods of soil analysis which can further be utilized by soil as well as forensic expert dealing with such cases.
Screening of organic compounds in complexly contaminated scrubber dust by GC × GC-MS and FT-ICR-MS Microchem. J. (IF 3.034) Pub Date : 2018-02-21 Nadja Dittrich, Jan Zuber, Philipp Rathsack
Theisen sludge is a complexly contaminated scrubber dust, which arised during the production of copper stone. Besides high contents of heavy metals, it also contains approximately 10% of a tar like organic fraction. Inorganic and organic components both represent an environmental risk and the assessment of potential remediation activities requires a detailed analysis of the contaminants. In this study, the organic part of the scrubber dust was analyzed by highly resolving gas chromatographic and mass spectrometric methods. Lower molecular weight compounds were analyzed by comprehensive gas chromatography (GC × GC-MS). A complex mixture of aliphatic and aromatic hydrocarbons was observed, which was predominantly composed of aromatic hydrocarbons with one to 4 rings with different number and length of alkylsubstituents. The most abundant heteroatomic compounds observed are benzo- and dibenzothiophenes and their alkylated homologues, but also phenols, carbazoles and acridines could be observed. Higher molecular weight compounds were analyzed by fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Two different ionization methods, electrospray ionization (ESI) and graphite assisted laser desorption ionization (LDI), were used in positive and negative ionization mode. Compounds with masses up to 1450 u are observed. The results were evaluated based on the number of formulas in the molecular formula classes and their distribution in double bond equivalents versus carbon number plots (DBE-nC plots). The results from both ionization polarities show significant differences regarding the quality of observed molecular formulas and both ionization methods.
One-pot synthesis of bovine serum albumin protected gold/silver bimetallic nanoclusters for ratiometric and visual detection of mercury Microchem. J. (IF 3.034) Pub Date : 2018-02-10 Rui Dai, Wenqing Deng, Pingyue Hu, Chao You, Lu Yang, Xue Jiang, Xiaoli Xiong, Ke Huang
A novel, rapid and ultrasensitive ratiometric and colorimetric fluorescence method was developed using bovine serum albumin protected gold/silver bimetallic nanoclusters (BSA-Au/Ag NCs) as fluorescent sensor for mercury (Hg) detection. The fluorescence sensor which was synthesized by one-pot approach shows dual-emissions at 470 nm (Ag NCs) and 630 nm (Au NCs) under a single excitation at 390 nm. In the presence of Hg2+, the red fluorescence of Au NCs was quenched while the fluorescence of Ag NCs almost unchanged, which exhibited a ratiometric fluorescence response and an obvious fluorescence color change toward Hg2+. The selective quenching mechanism may be due to the formation of gold amalgam bonds between Hg2+ (4f145d10) and Au+ (4f145d10). A limit of detection (LOD) of 2.2 μg L−1 and a relative standard deviation (RSD, n = 7) of 0.7% at a concentration of 50 μg L−1 of Hg2+ were obtained when using a commercial fluorescence spectrophotometer as the detector. In visual detection, as low as 10 μg L−1 of Hg2+ can be easily discriminated from the blank with the naked eye. The proposed method retains several unique advantages, including simplicity, rapidity, ease of usage and high-sensitively.
Profiles of polycyclic aromatic hydrocarbons in smoke from combustion and thermal decomposition of poplar wood pellets and sawdust Microchem. J. (IF 3.034) Pub Date : 2018-02-09 Biljana Škrbić, Vesna Marinković, Saša Spaić, Verica Milanko, Slađana Branovački
The aim of this paper is to determine the level and distribution of the sixteen polycyclic aromatic hydrocarbons (PAHs) listed by the US Environmental Protection Agency (US-EPA) in smoke from poplar wood pellets and sawdust combustion and thermal decomposition, respectively. Namely, the growth of selected poplar plantations, wood cultivation and production in the north part of the Republic of Serbia, Vojvodina Province, considerably increased. However, mechanical wood processing creates a lot of sawdust, which causes an occupational and environmental risk and also poses a fire hazard. Furthermore, in order to protect the environment and provide additional energy sources, sawdust is commonly pelletized and further used as a fuel. Thus, the assessment of environmental impact of its use becomes an important issue. Therefore, the intention of the authors was to determine the level and profile of PAHs emitted by combustion and thermal decomposition under atmospheric conditions of poplar wood pellets and sawdust. The 16 US-EPA PAHs were analyzed by gas chromatograph with mass selective detector. The level of total US-EPA 16 PAHs formed during combustion of wood pellets was 4.7 mg kg−1, whereas during the sawdust combustion it was 3.8 mg kg−1, while the resulting total PAHs concentration during thermal degradation under atmospheric conditions of pellets and sawdust was 3.4 mg kg−1 and 3.7 mg kg−1, respectively. The most common PAHs present in smoke from the combustion and thermal decomposition under atmospheric conditions of poplar wood pellets were phenanthrene, fluorene and naphthalene, while from the sawdust were phenanthrene, naphthalene, acenaphthylene and fluorene, respectively. BaPeq value obtained during the combustion of wood pellets was 0.081 mg kg−1, whereas from the combustion of sawdust it was 0.047 mg kg−1, while the resulting BaPeq value during the thermal degradation under atmospheric conditions of pellets and sawdust was 0.057 mg kg−1 and 0.049 mg kg−1, respectively. Biomass densification process did not affect PAHs emission neither during the combustion process nor the thermal decomposition process. To the best of our knowledge, it is the first study which considers the level and profile of PAHs found in smoke from the combustion and thermal decomposition of poplar clone I-214 (P. x euramericana cl. I-214) cultivated in the Republic of Serbia.
Sensitive and selective fluorometric determination and monitoring of Zn2+ ions using supermicroporous Zr-MOFs chemosensors Microchem. J. (IF 3.034) Pub Date : 2018-02-03 Islam M. El-Sewify, Mohamed A. Shenashen, Ahmed Shahat, Mahmoud M. Selim, Mostafa M.H. Khalil, Sherif A. El-Safty
Multianalytical approach to evaluate deterioration products on cement used as consolidant on lithic material: The case of Tello Obelisk, Lima (Peru) Microchem. J. (IF 3.034) Pub Date : 2018-02-17 Héctor Morillas, Maite Maguregui, Gladys Huallparimachi, Iker Marcaida, Cristina García-Florentino, Luis Lumbreras, Fernando Astete, Juan Manuel Madariaga
Exploiting CdSe/ZnS core-shell photocatalyst modified with cytochrome c for epinephrine determination in drugs utilized in cardiopulmonary resuscitation Microchem. J. (IF 3.034) Pub Date : 2018-02-10 André Silva Freires, Fernanda Maria dos Reis Lima, Sakae Yotsumoto-Neto, Saimon Moraes Silva, Flávio Santos Damos, Rita de Cássia Silva Luz
This work presents the development and application of a biosensor based on cadmium selenide/zinc sulphide core-shell quantum dot modified with the redox protein cytochrome c (CdSe/ZnS-Cytc) for the photoelectrochemical determination of epinephrine (EP). The photoactive biocomposite was immobilized on the surface of a glass substrate modified with indium doped tin oxide (CdSe/ZnS-Cytc/ITO). The photoactive film was characterized by electrochemical impedance spectroscopy and the photocurrent measurements were obtained by chronoamperometry using a LED light lamp as source of irradiation. After the experimental parameters optimization, the biosensor presented a good response for EP oxidation in a wide linear concentration range between 1 μmol L−1 and 1.2 mmol L−1 (with r = 0.999; n = 9). A detection limit of 2 nmol L−1 was obtained. The selectivity of the photosensor was evaluated against species such as uric acid, ascorbic acid, folic acid, barbital, glucose, and urea, and the results showed that the proposed biosensor has a good selectivity for the detection of EP. The CdSe/ZnS-Cytc/ITO photoelectrochemical biosensor was applied in injectable drug samples used in cardiopulmonary resuscitation. The recovery tests in the samples showed recovery values between 101 and 110% suggesting a good accuracy for the proposed method.
Determination of heterocyclic aromatic amines in airborne particulate matter (PM2.5 and PM10) from different emission sources by ultra-high performance liquid chromatography-tandem mass spectrometry Microchem. J. (IF 3.034) Pub Date : 2018-02-13 Romina Canales, Mariana Achad, Patricia Smichowski, Darío Gómez, Mario Reta, Soledad Cerutti
Determination of As, Sb and Hg in water samples by flow injection coupled HR CS ETAAS with an in situ hydride generator Microchem. J. (IF 3.034) Pub Date : 2018-01-07 A. Cárdenas Valdivia, M.M. López Guerrero, E.I. Vereda Alonso, J.M. Cano Pavón, A. García de Torres
A chelating sorbent which employs magnetic nanoparticles (MNPs) functionalized with 1,5-bis(di-2-pyridil)methylene thiocarbohydrazide (DPTH-MNPs) was used to develop a simple method for the analysis of trace amounts of metal ions (As, Sb and Hg) present in environmental samples combining on-line magnetic solid phase extraction (MSPE) with atomic spectrometry. The application of hydride generation with high resolution continuum source electrothermal atomic absorption spectrometry (HR CS ETAAS) improves the sensitivity of As, Sb and Hg determination. This method has proven to have a high sensitivity with detection limits of 0.25 μg L−1, 0.003 μg L−1 and 0.22 μg L−1 for As, Sb and Hg, respectively. Besides, the proposed method was applied in the sequential determination of the 3 elements mentioned above with a sample throughput of about 16.7 h−1, thereby, reducing the time of analysis and the volume of reagents and sample required. This method was applied to determine the target elements in a TMDA 54.5 and TM 24.3 certified reference materials, and seawater collected from Malaga Bay. The results showed good agreement with the certified values.
Hierarchical spheres In2S3-based cataluminescence sensor for ammonium sulfide Microchem. J. (IF 3.034) Pub Date : 2018-01-08 Pingyang Cai, Hongjie Song, Yi Lv
In the present work, three different kinds of In2S3: hierarchical microspheres A, B and C (HMa, HMb and HMc), which were synthesized by a hydrothermal method in the sodium dodecyl sulfate-thiourea (SDS-thiourea) system. XRD, SEM and BET were used to characterize the prepared In2S3 materials. Compared with the other two kinds of In2S3, the as-prepared In2S3 hierarchical microspheres B (In2S3 HMb) exhibit the best cataluminescence response to ammonium sulfide. The response and recovery times of the home-made ammonium sulfide gas sensor with In2S3 hierarchical microspheres B as sensing materials were about 8 s and 24 s, respectively. The linear dependence of the sensitivity on the ammonium sulfide concentration was observed in the range of 4–200 ppm with an excellent selectivity. These results indicated that In2S3 hierarchical microspheres B would be a good candidate for fabricating practical cataluminescence ammonium sulfide sensor.
Use of integrated non-invasive analyses for pigment characterization and indirect dating of old restorations on one Egyptian coffin of the XXI dynasty Microchem. J. (IF 3.034) Pub Date : 2018-01-05 Letizia Bonizzoni, Silvia Bruni, Marco Gargano, Vittoria Guglielmi, Chiara Zaffino, Andrea Pezzotta, Annalisa Pilato, Teodoro Auricchio, Luc Delvaux, Nicola Ludwig
The Royal Museums of Art and History of Brussels holds six coffins of the 21st Dynasty coming from a single discovery, the Second Cachette of Deir el-Bahari (Bab el-Gasus) (L. Delvaux & I. Therasse, Sarcophages. Sous les étoiles de Nout, Bruxelles 2015, p. 83–111). Since their discovery in 1891, their rich decorations have been subjected to deep manipulations during the years. In 2014, six coffins and four mummy-covers, the entire collection of the 21st Dynasty, were entrusted to the European Institute of Restoration for their diagnosis and restoration. In 2015, one compete coffin (composed by the external coffin, the internal one and the mummy cover) were the subject of a first targeted diagnostic campaign at the European Institute of Restoration laboratories. On this occasion, non-invasive in situ analyses have been performed on more than one hundred measuring points of the complete object, considering the five decorated parts (the two wooden anthropoid coffins composed by lid and base and the mummy-cover) showing both different technical features and pictorial materials. After a preliminary phase of analysis by imaging techniques such as Infrared Reflectography and Visible Fluorescence induced by UV, the pigments and binders were examined exploiting the synergy between four complementary techniques, namely EDXRF (energy dispersive X-ray fluorescence), FORS (fibre optics reflectance spectroscopy), reflection FTIR (Fourier transform infrared spectroscopy) and micro-Raman spectroscopy. The application of techniques with different penetration depths on more than one hundred points allowed to detect the stratigraphic sequences without sampling, opening to the interesting application to off-limits masterpieces. Based on imaging techniques, the painted surfaces showed areas with different features: dark areas with no UV fluorescence and low reflectance in IR, bright UV fluorescence and high IR reflectance (wavelength > 700 nm) and low-intensity UV fluorescence again with high reflectance in the infrared region. Such zones can be linked to the presence or absence of marker chemical elements (for instance Ba or Ti) or compounds that give hints about the presence and the period of the restorations. In these areas, an overlapping of a modern layer on the ancient and original one is the most probable current status of the pictorial stratigraphy. Original identified pigments include Egyptian blue, copper-based green, calcium carbonate and Red Ochre on an underlying Orpiment yellow layer. In the areas considered as already restored in the past on the bases of the analytical results, we find Azurite, Prussian blue, Egyptian Blue, Vermillion, Red Ochre, Chrome Red, Chrome Green, copper-based green, Zinc Yellow and Lead White. A layer composed of a natural resin was also detected by in-situ FTIR measurements; the resin could be more precisely identified as mastic by laboratory analyses.
Deterioration effects of wet environments and brown rot fungus Coniophora puteana on pine wood in the archaeological site of Biskupin (Poland) Microchem. J. (IF 3.034) Pub Date : 2018-01-04 Jeannette Jacqueline Łucejko, Marco Mattonai, Magdalena Zborowska, Diego Tamburini, Grzegorz Cofta, Emma Cantisani, Jozef Kúdela, Caroline Cartwright, Maria Perla Colombini, Erika Ribechini, Francesca Modugno
The archaeological site of Biskupin (Poland) is a prehistoric settlement dating to the 8th century BC, situated on a marshy island. Excavations started in 1934 and a considerable number of wooden artifacts were found in the lake water. Unfortunately, during many years of archaeological excavations, wooden remains deposited in the trenches were exposed to degradation and underwent considerable decomposition. Among the main causes of wood degradation, fungi and bacteria were the most destructive ones. The chemical effects induced by fungi and bacteria on wood are not well-known or studied. Here we present the investigation of a set of pine wood samples (Pinus sylvestris) buried in the Biskupin site, with the aim of reproducing the burial conditions of the original archaeological wood. Two monitoring stations (wet peat and lake water) were chosen and the samples were then removed from these burial environments after four and ten years. After removal, the samples were exposed to laboratory-controlled attack by the brown rot fungus Coniophora puteana. The final aim was to evaluate the effects of fungal activity on the wood substrates with different degrees of natural degradation. The study is part of an experiment designed to evaluate the short-term effects of the in situ preservation strategy adopted for the Biskupin archaeological woods. Various techniques were used to assess the physical and chemical degradation of the wood. The morphological changes induced by the exposure to the burial environment and by the action of the fungi were investigated using scanning electron microscopy (SEM). The chemical state of the wood was evaluated by using infrared spectroscopy (FTIR), analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) and XRD spectroscopy. Fungal action caused the depletion of polysaccharides resulting in mass loss and the FTIR spectra of the wood samples highlighted that cellulose was more degraded with respect to hemicelluloses. This trend correlated with an increase in the relative abundance of furans, which are among the main pyrolysis products of polysaccharides. Fungal attack also induced oxidation of lignin and an increase in the crystallinity index of cellulose, which points towards a preferential metabolisation of amorphous cellulose. The overall results highlighted that the burial in these wet environments caused changes mostly in the hemicelluloses, whereas the fungal attack was mainly directed to cellulose degradation.
Printing materials and technologies in the 15th–17th century book production: An undervalued research field Microchem. J. (IF 3.034) Pub Date : 2017-12-14 F. Albertin, E. Balliana, G. Pizzol, G. Colavizza, E. Zendri, D. Raines
We present a systematic non-invasive investigation of a large corpus of early printed books, exploiting multiple techniques. This work is part of a broader project – Argeia – aiming to study early printing technologies, their evolution and, potentially, the identification of physical/chemical fingerprints of different manufactures and/or printing dates. We analyzed sixty volumes, part of the important collection of the Ateneo Veneto in Venice (Italy), printed between the 15th and the 17th centuries in the main European manufacturing centers. We present here the results of the imaging analysis of the entire corpus and the X-ray fluorescence (XRF) investigation performed, focusing on the XRF data and their statistical treatment using a combination of Principal Component Analysis (PCA) and Logistic Regression. Thanks to the broad XRF investigation – more than 200 data points – and to the multidisciplinary approach, we were able to discriminate the provenances of the paper – in particular for the German and Venetian volumes – and we potentially identified a chemical fingerprint of Venetian papers.
The green grass was never green: How spectroscopic techniques should have assisted restoration works Microchem. J. (IF 3.034) Pub Date : 2018-01-09 Ilaria Costantini, Marco Veneranda, Mireia Irazola, Julene Aramendia, Kepa Castro, Juan Manuel Madariaga
This paper presents the results of a multidisciplinary research based on the use of different diagnostic techniques for the study of wall paintings that belong to the late Gothic period and are preserved in the church of Saint Stephen in Ribera de Valderejo (Álava, Basque Country). Portable Raman and X-ray fluorescence spectroscopy measurements carried out in-situ allowed to characterize the plaster composition, the colour palette used by the artists and the materials employed during the restoration works in recent times. The analyses were focused especially on some areas that appear unusually grey. Apparently, the results obtained by both techniques seem to be contradictory and it was necessary to perform a selective sampling in some areas of interest which were analyzed in the laboratory. Raman spectroscopy and scanning electron microscope, coupled with energy dispersive X spectroscopy, applied on the cross-section of micro samples, made possible to clarify some important issues, showing the inadequacy of the restoration works carried out in previous years and the presence of a potentially dangerous material too (magnesium arsenate), whose use was not documented. The results demonstrated the importance of using diagnostic tools for the identification of the materials belonging to Cultural Heritage, especially before restoration works in order to choose the most appropriate methodology and to respect the original appearance of the paintings.
Non-invasive analysis of a 15th century illuminated manuscript fragment: point-based vs imaging spectroscopy Microchem. J. (IF 3.034) Pub Date : 2018-01-05 Stijn Legrand, Paola Ricciardi, Luca Nodari, Koen Janssens
Illuminated manuscript fragments are some of the best preserved objects of Western cultural heritage. Therefore, scholars are limited to non-invasive - often point-based - methods, to answer questions on material usage, technique, origin and previous treatments. These powerful methods yield specific information; however, the information is limited to the number of points analyzed. Imaging spectroscopies such as MA-XRF and MA-rFTIR combine specificity with the power of imaging, resulting in distribution images that are interpretable by non-spectroscopists and the public at large. In this paper the possible added value of using imaging spectroscopy is discussed. Do these methods yield the same results as an extensive point-based spectroscopic campaign and can they bring novel information? As a case study, a 15th century illuminated manuscript fragment is employed in order to explore the differences between these approaches and present an inventory of their advantages and limitations.
Electrochemical biosensor based on ionic liquid polymeric microparticles. An analytical platform for catechol Microchem. J. (IF 3.034) Pub Date : 2018-01-10 Marta Sánchez-Paniagua López, Beatriz López-Ruiz
Data fusion applied to the photodegradation study of ciprofloxacin using hyphenated detection systems (UV–Vis and fluorescence) and multivariate curve resolution Microchem. J. (IF 3.034) Pub Date : 2018-01-11 M. Razuc, B.S. Fernández Band, M. Garrido
Handy cloud point extraction coupled with inductively coupled plasma mass spectrometry for analysis of trace zirconium in complex biological samples Microchem. J. (IF 3.034) Pub Date : 2018-01-12 Juan Gui, Chaoting Huang, Jiahao Yuan, Qingmei Huang, Fei Long, Ande Ma, Jialiang Pan
Bioactive screening of complex tea samples using the ferric reducing antioxidant power assay incorporating reaction flow HPLC columns for post column derivatisations Microchem. J. (IF 3.034) Pub Date : 2018-01-06 Andrew Jones, Agustín Acquaviva, Gary R. Dennis, R. Andrew Shalliker, Arianne Soliven
This is the first study to employ a reaction flow (RF) HPLC column of a short 5 cm length to identify antioxidants in a variety of complex samples represented by tea, utilising simultaneous multiplexed detection techniques. The detection responses included: underivatised UV at 280 nm, underivatised fluorescence detection (FLD) and a post column derivatisation (PCD) colorimetric response for antioxidants via the ferric reducing antioxidant power (FRAP) assay. Both similarities and differences in the chromatograms obtained using the three detection modes highlight the power of multiplexed detection. The main findings from the bioactive profiling include: the Fruit of the Forest tea contains the lowest level of antioxidants and is clearly distinct from the other three teas which are based on Camellia sinensis. The antioxidants detected in the green tea and the two black teas are similar. The green tea contains a higher concentration of the two main antioxidants that eluted at 4.0 and 5.7 min. The simplicity of sample analysis and chemical profiling using RF columns and selective detection was the focus of this study via the analysis of antioxidants in tea using the FRAP reagent. The main advantage of RF-PCD is the ability to split flows for simultaneous detection with minimal post column dead volume contributions, making peak matching between detectors much easier. To date, few studies exploit the power of RF-PCD multiplexed detection to differentiate and identify bioactive compounds in various complex samples. Applications of the approach developed in this study may include antioxidant screening and profiling of natural products, foods and beverages.
Laser-based spectrometer for optical trace gas detection in young adults with autism Microchem. J. (IF 3.034) Pub Date : 2018-01-12 Ana M. Bratu, Mioara Petrus, Cristina Popa
Autism is known as a complex neurodevelopmental disability that involve a combination of impairments in communication, reciprocal social interaction, and stereotypic behaviors. Many studies linked oxidative stress (OS) with the etiopathogenesis of Autism Spectrum Disorders (ASD), but the literature reports somewhat contradictory results. The aim of our study was to evaluate ethylene as a by-products of OS in human body, in people with autism. We used a laser-based spectrometer for optical trace ethylene detection. The results indicated that OS was not significantly increased in this disorder. As a by-product of OS exhaled ethylene from adults with autism presented very small concentration differences compared to healthy controls. The possible responsible factor for the normality between the concentrations of breath ethylene at young adults with autism and control adults could be explained by the antioxidants intake together with the lifestyle and dietary patterns. Additional studies are needed to determine carefully which antioxidant will have the greatest therapeutic benefit considering the importance of oxidative stress in many biological reactions.
Towards a Surface Enhanced Raman Scattering (SERS) spectra database for synthetic organic colourants in cultural heritage. The effect of using different metal substrates on the spectra Microchem. J. (IF 3.034) Pub Date : 2018-01-11 Clarimma Sessa, Ruben Weiss, Reinhard Niessner, Natalia P. Ivleva, Heike Stege
Two different silver colloids were synthetized using the reducing agents sodium citrate (Lee-Meisel method) and hydrochloric hydroxylamine (Leopold-Lendl method). The properties of these colloids were evaluated by investigating a selection of 25 synthetic organic dyes and pigments that belong to different chemical classes and whose Raman spectra are usually poor or are overwhelmed by fluorescence. The observed changes in the SERS spectra acquired using both colloids were evaluated and interpreted by taking into account that enhancement of the Raman signal is influenced by the localised plasmon resonance on the silver nanoparticles as well as by the chemical affinity and molecule orientation on the metal substrate. The morphology and plasmon resonance of the single nanoparticles were characterised by means of UV–Vis absorption spectroscopy. The results revealed significant differences in terms of stability and reproducibility. Furthermore, the sensitivity of the colloids and the reproducibility of the different measurements were evaluated in terms of the Raman shift and signal intensity. SERS spectra of triarylcarbonium (BV 14, BG 1, AB 110, AB 83, PB 1, PG 1) and xanthene colourants without halogen substituents (BV 10, PV 1, BR 1, PR81) as well as the nitro dye AY 24 were very reproducible with both colloids; however, others, such as brominated xanthene dyes (AR 87, AR 91), thioindigo pigments (PR 88, PR 181) and anthraquinone colourants, may present different spectral features depending on the colloid used, which should be taken into account when interpreting unknown spectra. The hydroxylamine-reduced colloid, besides being a reproducible and easy-to-produce SERS substrate, gave satisfactory spectra with all the SERS-active dyes and pigments that were examined. Based on the results, we assume that the hydroxylamine-reduced substrate is the best choice for acquiring spectra for a future SERS database for cultural heritage (CH) applications.
On the origin of Goa Cathedral former altarpiece: Material and technical assessment to the work of Garcia Fernandes, Portuguese painter from 16th century Lisbon workshop Microchem. J. (IF 3.034) Pub Date : 2018-01-16 Vanessa Antunes, António Candeias, José Mirão, Maria L. Carvalho, Vitor Serrão, Cristina Barrocas Dias, Ana Manhita, Ana Cardoso, Marta Manso
Goa Cathedral former altarpiece is one of the oldest set of paintings in India. The seven remaining paintings from the first altarpiece of Goa Cathedral, nowadays in the sacristy, are attributed by some art historians to Master Garcia Fernandes (act. 1514–1565), Portuguese painter from Lisbon workshop. The 16th century was the “Golden age” of Portuguese painting. In this context the Royal Lisbon workshop played a predominant role, where the activity of the painter Garcia Fernandes and his workshop can be distinguished. In this new approach, Goa paintings are being studied and compared with other works in Portuguese territory attributed to this same painter, as St. Bartholomew altarpiece from the chapel of Bartolomeu Joanes in Lisbon Cathedral. The stratigraphic study allowed to compare ground layers, pigments and binders which, were characterized using complementary analytical and imaging techniques: (X-ray Fluorescence spectrometry (XRF), Infrared Reflectography (IRR), Infrared Photography (IRP), Macro Photography (MP), micro-X-ray Diffraction (μ-XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Raman micro-spectroscopy (μ-Raman), Fourier Transform Infrared micro-spectroscopy (μ-FTIR), Pyrolysis gas chromatography mass spectrometry (PY-GC/MS). This work brought a new insight on the techniques and materials used in this Masterpiece and highlighted the conclusion that Goa Cathedral former altarpiece must be a Portuguese production.
In situ macro X-ray fluorescence (MA-XRF) scanning as a non-invasive tool to probe for subsurface modifications in paintings by P.P. Rubens Microchem. J. (IF 3.034) Pub Date : 2018-01-16 Geert Van der Snickt, Stijn Legrand, Ina Slama, Eva Van Zuien, Gerlinde Gruber, Katlijne Van der Stighelen, Lizet Klaassen, Elke Oberthaler, Koen Janssens
Within the last decade, the established synchrotron- and laboratory-based micro-XRF scanning technology inspired the development of mobile instruments that allow performing in situ experiments on paintings on a macro scale. Since the development of the first mobile scanner at the start of this decade, this chemical imaging technique has brought new insights with respect to several iconic paintings, especially in cases when standard imaging techniques such as X-Ray Radiography (XRR) or Infrared Reflectography (IRR) yielded ambiguous results. The ability of scanning MA-XRF to visualise the distribution of elements detected at and below the paint surface renders this spectrometric method particularly helpful for studying painting techniques and revealing materials that remain hidden below the paint surface. The latter aspect is especially relevant for the technical study of works by Pieter Paul Rubens (1577–1640) as this highly productive seventeenth century master is particularly renowned for the continuous application of modifications during (and even after) the entire course of the creative process. In this work, the added value of MA-XRF scanning experiments for visualising these subsurface features is exemplified by interpreting the chemical images obtained on three of Rubens' key works. Special attention is given to three types of adjustments that are particularly relevant for the technical study of Rubens' oeuvre: (1) compositional changes (‘pentimenti’), exemplified by results obtained on The Portrait of Hélène Fourment (ca. 1638), (2) extensions to the support (‘Anstückungen’), illustrated by imaging experiments performed on the Venus Frigida (1614) and (3) Rubens' intriguing halos around flesh tones, as found amongst others in The Incredulity of Saint Thomas (1613). The ensuing insights in the paint stratigraphy and the underlying supporting structure illustrate the potential of MA-XRF scanning for the non-invasive, comparative study of Rubens' oeuvre. The results do not only augment the understanding of the complex genesis of Rubens' works of art and his efficient painting technique, but prove valuable during conservation treatments as well, as addressed in this paper.
XRD, SEM/EDX and micro-Raman spectroscopy for mineralogical and chemical characterization of iron slags from the Roman archaeological site of Forua (Biscay, North Spain) Microchem. J. (IF 3.034) Pub Date : 2018-01-16 Haizea Portillo, Maria Cruz Zuluaga, Luis Angel Ortega, Ainhoa Alonso-Olazabal, Xabier Murelaga, Ana Martinez-Salcedo
The Roman village of Forua (North Spain) was an important iron production and distribution centre during the 1st-4th centuries AD. Different metallurgical materials at the archaeological site were identified as forged slag, bog ore mineral and refractory materials used in the walls and on the floor of furnaces. The samples were studied by macroanalysis and microanalysis techniques. The mineralogical characterization was carried out via optical microscopy and X-ray powder diffraction, and the textural characteristics and the composition of individual phases were determined using scanning electron microscopy coupled with electron-dispersive spectroscopy, and by Raman microspectroscopy. Mineral associations not only reflect furnace cooling rates and temperatures but also indicate quartz was the main flux used. The microanalysis results reflect the elements that constituted the slags and other materials from the forge and the worked metallic materials. The results showed the slags originated from iron smithing, which also was confirmed by the presence of iron particles. The ore materials consisted of goethite.
Development of a new portable X-ray powder diffractometer and its demonstration to on-site analysis of two selected old master paintings from the Rijksmuseum Microchem. J. (IF 3.034) Pub Date : 2018-01-04 Airi Hirayama, Yoshinari Abe, Annelies van Loon, Nouchka De Keyser, Petria Noble, Frederik Vanmeert, Koen Janssens, Kriengkamol Tantrakarn, Kazuo Taniguchi, Izumi Nakai
A portable X-ray powder diffractometer (p-XRD) PT-APXRD III has been developed for on-site analysis of paintings and archaeological samples. By using a Cu anode X-ray tube and a silicon drift diode (SDD) detector, diffraction patterns with a high signal-noise (S/N) ratio can be recorded. The X-ray tube can be operated at a maximum voltage of 60 kV, which makes it possible to simultaneously record X-ray fluorescence spectra up to the high-energy region. The total weight of this instrument is 16 kg, which can be carried anywhere and the goniometer unit (5.6 kg) can be placed on a tripod for analysis of mural paintings. We brought the instrument to the Rijksmuseum in the Netherlands to examine its applicability for the analysis of oil paintings. We successfully analyzed two seventeenth-century oil paintings by Johannes Vermeer and Jan Davidsz de Heem (copy after). Ultramarine blue, lead-tin yellow type I, and Naples yellow were identified from the diffraction patterns, demonstrating the high practicality of this instrument. Furthermore, it was found from the SEM-EDX analysis of a paint cross section that the yellow pigment was applied in separate layers rather than being mixed. This diffractometer will be commercially available in the near future and will have many applications in the field of material analysis.
A non-invasive stratigraphic study by reflection FT-IR spectroscopy and UV-induced fluorescence technique: The case of historical violins Microchem. J. (IF 3.034) Pub Date : 2018-01-23 Claudia Invernizzi, Giusj Valentina Fichera, Maurizio Licchelli, Marco Malagodi
In the Cultural Heritage field, stratigraphic analysis is commonly carried out by applying microscopic and micro-analytical techniques to cross-sections of micro-samples taken from artwork. This methodology provides the most comprehensive information on the object's physical structure, but necessarily implies the loss of precious or unique fragments. For this reason, sampling is rarely feasible on musical instruments having such a historical and commercial value as Stradivari or Guarneri violins. Having been played over the centuries, these masterpieces have undergone different kinds of degradation and wear, and subsequent invasive restorations. Varnish layers have therefore been thinned or even removed from the surface and other materials could have been added overlaying the original ones, with consequent variations in coating thickness and composition over time. In the present work, a novel non-destructive and non-invasive methodology combined UV-Induced Fluorescence (UVIFL) photography and reflection FT-IR spectroscopy to investigate how and to what extent varnish thicknesses vary on the surface of historical violins as well as to reconstruct the stratigraphic layer order and chemical composition. Firstly, UV-induced variations and IR diagnostic bands were identified on numerous model samples reproducing musical instrument stratigraphy. Then the methodology was applied to the study of several Stradivari and Guarneri violins and its limitations and strengths were showed in three representative case studies.
Scientific investigation into the water sensitivity of twentieth century oil paints Microchem. J. (IF 3.034) Pub Date : 2018-02-02 Judith Lee, Ilaria Bonaduce, Francesca Modugno, Jacopo La Nasa, Bronwyn Ormsby, Klaas Jan van den Berg
In order to develop a better understanding at the molecular level of water sensitivity in twentieth century oil paintings, water sensitive Winsor & Newton oil paint swatches and twentieth century oil paintings were characterised using gas chromatography–mass spectrometry (GC–MS) and direct injection electrospray ionisation mass spectrometry (ESI-MS), and the data were analysed using principal component analysis. Liquid chromatography coupled with tandem mass spectrometry based on quadrupole and time of flight mass detectors and electrospray interface (HPLC-ESI-Q-ToF) was also used to obtain a better insight into the molecular composition of a selection of samples. The study highlights a strong relationship between the molecular composition of the binding medium and the type of pigment present in the paint, which relates to water sensitivity. Consistently non-water sensitive lead white, titanium white, and zinc white paints [all containing zinc oxide] contained a relatively low proportion of extractable diacids, and a relatively high proportion of extractable short chain monoacids. These paints also contained a relatively low level of unsaturated and hydroxylated glycerides. Water sensitive iron oxide and ultramarine paints are associated with both a relatively high degree of oxidation and a high proportion of extractable diacids, as well as a relatively high content of unsaturated and hydroxylated glycerides. Water sensitive cadmium red, yellow and orange paints were generally not highly oxidised, but they also contained a relatively high content of unsaturated and hydroxylated glycerides. It is hypothesised that water sensitivity relates to a low degree of saponification and crosslinking and possibly, on the relative content of dicarboxylic acids.
Emitter/receiver piezoelectric films coupled to flow-batch analyzer for acoustic determination of free glycerol in biodiesel without chemicals/external pretreatment Microchem. J. (IF 3.034) Pub Date : 2018-02-02 Gabriel M. Eggly, Matías Blackhall, Adriano de Araújo Gomes, Rodrigo Santos, Mário César Ugulino de Araújo, Marcelo F. Pistonesi
This paper describes for the first time the use of emitter and receiver piezoelectric films coupled one in front of the other into a flow-batch analyzer for acoustic determination of free glycerol in biodiesel without chemicals/external pretreatment. Online extraction of free glycerol from biodiesel was carried out into aqueous solution without chemicals/external pretreatment. While the emitter piezoelectric is activated to sonicate the solution, the receiver piezoelectric translates the acoustic signal received into an electrical signal, which is measured and recorded by a digital oscilloscope. Multivariate calibration models were built for prediction of free glycerol concentration. In this sense, results of partial least square regression (PLS), the interval PLS (iPLS) and PLS coupled with the Successive Projections Algorithm for interval selection (iSPA-PLS) were compared. The proposed low-cost flow-batch analyzer exhibited good performance, satisfactory detection limit (0.12 mg kg−1) and a linear response from 72 to 372 mg kg−1 of free glycerol in biodiesel. The procedure was successfully applied to the analysis of biodiesel samples, and the results agreed with the reference method (ASTM D6584-07) at 95% confidence level.
Multi-technique characterisation of medieval mastic encrustation sculptures Microchem. J. (IF 3.034) Pub Date : 2018-02-03 Inez Dorothé van der Werf, Giulia Germinario, Pasquale Acquafredda, Luigia Sabbatini
Mastic incrustation sculptures were used to decorate different types of objects by filling the marble incisions with an impasto containing materials such as crushed pottery, glass or rock fragments, possibly in combination with organic substances, and was employed both in Byzantine and Occidental areas. From the 11th century onwards these sculptures are applied in important churches such as San Marco in Venice (Italy), but, despite their widespread use and conservation problems, the composition of these amalgams has never been thoroughly studied. Here we present the results of the examination of the mastic encrustations present on the medieval marble panels and precious cathedra in the San Nicola church of Bari (Italy). The matrix was analysed with Fourier transform infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry. Organic binders were found and, in particular, the occurrence of heated Pinaceae resin, as well as of beeswax was assessed. The inclusions, including different types of rock, carbon black and opaque glass fragments, were characterised with optical microscopy, scanning electron microscopy, and powder X-ray diffraction. Micro-Raman spectroscopy was carried out on both inclusions and matrix.
Surface-enhanced Raman scattering enhancement due to localized surface plasmon resonance coupling between metallic nanoparticles and substrate Microchem. J. (IF 3.034) Pub Date : 2018-02-03 Jun-Liang Chen, Tsunghsueh Wu, Yang-Wei Lin
Mercury(II) adsorption by a novel adsorbent mercapto-modified bentonite using ICP-OES and use of response surface methodology for optimization Microchem. J. (IF 3.034) Pub Date : 2018-02-03 Tekin Şahan, Funda Erol, Şakir Yılmaz
The presence of mercury(II) ions in aqueous media is a major concern due to toxicity and the threat to public health and ecological systems. Thus, the development of novel adsorbents that are highly efficient and selective is of critical importance for the removal of mercury(II) ions from aqueous media. The adsorption of mercury(II) from aqueous media by a new adsorbent, 3-mercaptopropyl trimethoxysilane-modified bentonite (B-SH), and the optimization of adsorption parameters was investigated in this study. B-SH was used as a novel sorbent for mercury(II) adsorption, and the analysis of adsorption conditions was performed by response surface methodology (RSM). The characterization of B-SH was executed using Brunauer, Emmett and Teller (BET), Fourier Transform Infrared (FTIR) Spectroscopy, Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses. The most important parameters for Hg(II) adsorption were initial pH, initial mercury(II) concentration (Co), temperature (T (°C)), and adsorbent dosage (g). The RSM results showed that the optimal adsorption conditions yielding the best response were 6.17, 36.95 mg/L, 37.28 °C, and 0.19 g, for pH, Co, T (°C), and adsorbent dosage, respectively. At optimum adsorption conditions obtained by program, the maximum adsorption capacities and the adsorption yield were 19.30 mg/g and 99.23%, respectively. Among the adsorption isotherm models (the Langmuir, Freundlich and Dubinin-Radushkevich), the adsorption data showed a better fit to the Langmuir isotherm model. The thermodynamic studies revealed that the adsorption process was spontaneous, feasible and endothermic. According to these results, B-SH has high mercury(II) adsorptive removal potential from aqueous media. In addition, a new adsorbent has been added to the literature for the uptake of toxic metals like mercury.
Interdisciplinary approach to develop a disposable real time monitoring tool for the cleaning of graphic artworks. Application on “le Nozze di Psiche” Microchem. J. (IF 3.034) Pub Date : 2018-02-03 L. Micheli, C. Mazzuca, M. Missori, L. Teodonio, A. Mosca Conte, O. Pulci, L. Arcadipane, S. Dominijanni, A. Palleschi, G. Palleschi, S. Iannuccelli, S. Sotgiu
Disposable non-invasive and compatible real time monitoring tool was developed in order to follow the cleaning process of paper artwork directly in situ. This tool was based on a biocompatible cleaning hydrogel coupled with flow electrochemical diagnostic tool, suitable to verify in situ and in a simple way the assessment of degradation of artwork and the efficiency of cleaning process. In this paper, the results obtained by applying this tool on a great format artwork with a lining as support, “Le Nozze di Psiche”, engraved by Diana Scultori, printed in 1613, are reported. This opera was affected by a structural and chromatic deterioration due to a strong oxidative degradation. Such deterioration was probably accelerated by the adhesive (a mixture of starch paste and animal glue) used in a previous lining intervention. In this case, the cleaning agents used are rigid hydrogels of Gellan gum, modified with hydrolytic enzymes. By using the flow sampling system, all materials removed by the gel was carried up to a thin layer cell containing a selective electrochemical biosensors, suitable to monitor both treatments, the cleaning process and the removal of lining. These were monitored, allowing understanding when both processes were completed, thus avoiding lengthy and unnecessary cleaning applications. The effectiveness of cleaning with Gellan gel was assessed quantitatively by using non-invasive optical reflectance spectroscopy by a portable instrumentation, elaborating data with an improved version of the Kubelka-Munk theory in order to recover the absorption coefficient of the cellulose fibers of “Le Nozze di Psiche”. The concentration of oxidized groups acting as chromophores was obtained by comparing the experimental optical absorption spectra to those simulated computationally by using TDDFT-based calculations. By following the cleaning with Gellan gel the results indicate a large decrease of the concentration of degradation product of cellulose. Moreover, chromatographic analysis were carried out in order to evaluate the amount of acid compound, produced during the aging and present on the graphic artwork, using the Gellan gel after cleaning step. The results obtained from the restoration of “Le Nozze di Psiche” have allowed the restorers to evaluate innovative methods for cleaning treatment of paper artworks with a highly specialized scientific-diagnostic approach.
A green cyclodextrin metal-organic framework as solid-phase extraction medium for enrichment of sulfonamides before their HPLC determination Microchem. J. (IF 3.034) Pub Date : 2018-02-02 Yuanyuan Li, Nan Zhu, Tong Chen, Yulong Ma, Qiang Li
A facile approach was used to prepare a cyclodextrin metal–organic framework(CD-MOF) based on γ-cyclodextrins (γ-CDs) and alkali metal cations. As a green, renewable framework material, the CD-MOF exhibits high selectivity and sorptive capacity toward sulfonamides (SAs). Therefore, five SAs including sulfathiazloe(STZ), sulfamethoxymidine(SMD), sulfamerazine(SMR), sulfadimethoxine (SDM)and sulfaquinoxaline (SQX) were selected as target analytes to validate the extraction performance of CD-MOF as a solid-phase extraction (SPE) adsorbent, coupled with high-performance liquid chromatography (HPLC) and the adsorption mechanism was investigated. The results showed that the CD-MOF as adsorbent exhibited good enrichment capability for five SAs and obtained short adsorption equilibrium time(30 min). Under optimized conditions, the spiked recoveries into meat samples were satisfied (76%–102%) with relative standard deviation below 2.4%–6.5% (n = 3) which indicated that the method was suitable for the effective extraction of SAs from complicated matrices.
A highly-sensitive microplate fluorimetric method for the high-throughput determination of nitrate ion in aqueous compost extracts Microchem. J. (IF 3.034) Pub Date : 2018-01-31 Marco Ciulu, Nadia Ollivier, Carine Demelas, Jean-Luc Boudenne, Bruno Coulomb, Frédéric Théraulaz, Fabien Robert-Peillard
In this paper, a new spectrofluorimetric method for the determination of nitrate in aqueous compost extracts is presented. The microplate procedure is based on the reduction of nitrate to ammonium by means of Zn powder under acidic conditions and the following derivatization of ammonium with o-phthalaldehyde (OPA) and N-acetylcysteine (NAC) to give a fluorescent derivative. Optimization work allowed performing the reduction in 30 min on a small sample volume (150 μL) and using a little quantity of metal (20 mg). The use of strong acids is also avoided. Excellent limit of detection was achieved (1.3 μM = 0.08 mg L−1 NO3−) along with good precision levels (4.2 and 14.3% for 50 and 5 μM, respectively) and a satisfactory linear dynamic range (4–100 μM). A good agreement between data coming from our method and from ion-exchange chromatography was found on real compost samples, indicating a good level of accuracy.
Response surface methodology for the optimization of phenolic compounds extraction from extra virgin olive oil with functionalized gold nanoparticles Microchem. J. (IF 3.034) Pub Date : 2018-01-31 Ilaria Fratoddi, Mattia Rapa, Giovanna Testa, Iole Venditti, Francesca Anna Scaramuzzo, Giuliana Vinci
Micro-EDXRF, SEM-EDS and OM characterisation of tin soldering found in handle attachments of Roman situlae from Conimbriga (Portugal) Microchem. J. (IF 3.034) Pub Date : 2018-02-02 F. Lopes, R.J.C. Silva, M.F. Araújo, V.H. Correia, L. Dias, J. Mirão
Tin (Sn) or a Sn-rich solder applied to copper-based artefacts has been frequently used at least, since the Ancient Greece, although scarce studies have been published concerning the technology of this metallurgical joining technique. Several filler remnants were reported to be found in a Roman collection of handle attachments of situlae or cauldrons (2nd century BCE–5th century CE) from the archaeological site of Conimbriga, a Roman city from the Lusitania Province (Portugal). All these artefacts were cast in high leaded coppers and bronzes. The present study aims to contribute to the knowledge of Sn-rich soldering, an ancient metallurgical joining technique, by the characterisation of the fusible metallic alloy present in 10 Roman artefacts by means of micro-energy dispersive X-ray fluorescence spectrometry (micro-EDXRF), scanning electron microscopy with energy dispersive X-ray (SEM-EDS) microanalysis and optical microscope (OM) observations. Results of studied solders show the presence of Cu-Sn alloys, with Sn contents ranging from δ to η phase composition (30–60 wt% Sn). As the attachments were made in leaded copper alloys, it was also observed, in some cases, the melting of the interdendritic Pb-rich chains with long-range diffusion of the solder alloy into the substrate. The fillers compositions suggest that the handle attachments have been joined to a situla body by the soldering metallurgical process with Sn or a Sn-rich alloy. The studied leaded Cu-Sn attachments, probably formulated by local craftsman, were joined into the body of a situla or cauldron with a soft solder (soldering), a common metallurgical joint from Antiquity, although no relation was found between composition or typology and the Sn or Sn-rich solder.
New advanced extraction and analytical methods applied to discrimination of different lichen species used for orcein dyed yarns: Preliminary results Microchem. J. (IF 3.034) Pub Date : 2018-01-31 Ilaria Serafini, Livia Lombardi, Massimo Reverberi, Alessandro Ciccola, Elisa Calà, Fabio Sciubba, Marcella Guiso, Paolo Postorino, Maurizio Aceto, Armandodoriano Bianco
In this paper, the preliminary results of a study aimed to discriminate between the different species of lichens, from which orchil dyes originate, are presented. A multi-analytical approach has been used to analyze several species of lichens, in particular Roccella tinctoria DC, Lasallia pustulata L. and Ochrolechia tartarea L., in an attempt to identify distinguishing markers within different orchil mixtures. In the first part of the research, samples of yarns dyed with the different species, prepared in laboratory after the proper raw lichens treatment, have been subjected to SERS on fiber analyses. Hence an innovative ammonia protocol has been applied to all the specimens. Firstly, in order to evaluate the difference among the different species, HPTLC has been applied to the extracts of dyed yarns and the dye baths. All the spots present on the TLC plates have been analyzed through SERS (HPTLC-SERS), in order to obtain a SERS database of each single compound, fixed on the yarns. Then, HPTLC-MS and HPLC-MS experiments have been carried out, in order to deep into the identification of compounds corresponding to each spot.
Miniaturized dielectric barrier discharge–atomic emission spectrometer for pesticide: Sensitive determination of thiram after derivatization with mercurial ion Microchem. J. (IF 3.034) Pub Date : 2018-01-31 Bingjun Han, Ya Li, Yan He, Daizhu Lv, Lixu Peng, Huamei Yu
A novel method was developed to sensitively determine thiram (which we selected as a representative large molecular organic pesticide) using miniaturized dielectric barrier discharge-atomic emission spectrometry (DBD-AES), based on the determination of free mercurial ion (Hg2+) from Hg labeled thiram complex. The disulfide bond (SS) in thiram was reduced to sulfhydryl (SH) using tris(2-carboxyethyl)phosphine (TCEP), and inorganic Hg2+ was used as the derivatization reagent. It was found that SnCl2 could selectively reduce only free Hg2+ to Hg0 vapor in the presence of Hg2+-labeled thiram complex, which could be separated from sample matrices for sensitive DBD-AES detection. Under the optimized conditions, this method provided high sensitivity for thiram determination, with limits of detection as low as 0.0003 mg kg−1 and linear dynamic ranges of 0.001–0.01 mg kg−1. This analytical method performs better than the traditional analytical methods, demonstrating the potential usefulness and versatility of this new Hg-labeled DBD-AES system.
GC–MS detection and determination of major volatile compounds in Brassica juncea L. leaves and seeds Microchem. J. (IF 3.034) Pub Date : 2018-01-12 Anubhuti Sharma, P.K. Rai, Surendra Prasad
This investigation reports the detection and determination of the chemical components from polar extract of the seeds and leaves of Indian Mustard i.e. Brassica juncea L. genotypes using gas chromatography-mass spectrometry (GC–MS). Many of the components in Brassica juncea L. seeds and leaves are essential for proper human nutrition as primary and secondary metabolites. The main phytochemicals identified in seeds were 2-butyl isothiocyanate (32.46%), phenylethyl isothiocyanate (28.01%), α-d-galactopyranoside (25.19%), linolenic acid (16.05%), tetradecanoic acid (11.32%) and oleic acid (15.30%). The GC–MS results clearly show that the major compounds identified in the leaves were α-methyl-d-mannopyranoside (27.18%), 2-butyl isothiocyanate (24.24%), β-d-glucopyranoside (24.54%), furaldehyde (15.96%), 1-phenyl ethanol (23.33%), ethyl benzoate (14.50%), linolenic acid (13.99%) and oleic acid (12.75%). The study confirmed that the glucosinolates with allyl and phenylethyl groups as side chain are predominant compounds in Brassica juncea L. Due to variable patterns of bioactive compounds Brassica extract could be used as natural antioxidant and source for various medicinal purposes.
Simultaneous determination of iridoids, phenylpropanoids and flavonoids in Lippia alba extracts by micellar electrokinetic capillary chromatography Microchem. J. (IF 3.034) Pub Date : 2018-02-03 Angélica F. Gomes, Markus Ganzera, Stefan Schwaiger, Hermann Stuppner, Maria Halabalaki, Maiara P. Almeida, Mateus F. Leite, Juliano G. Amaral, Jorge M. David
A new method for the determination of three different classes of secondary metabolites (flavonoids, iridoids and phenylpropanoids) present in extracts of Lippia alba leaves based on CE is described. The capillary electrophoretic separation of these compounds was possible employing a 50 mM borax buffer containing 75 mM SDS and 5% isopropanol as organic modifier. The analytes could be well resolved in 25 min and accurately determined in different chemotypes of Lippia alba specimens. Method validation assured the compliance of the assay to International Conference on Harmonization standards (ICH) (correlation coefficients ≥0.9944, LOD 23.0–65.0 μg ml−1 and LOQ 38.0–119.0 μg ml−1, recovery rates from 97 to 101%, intermediate precision ≤2.1%, and repeatability ≤5.0%). The proposed method was compared with a previously validated HPLC method using eight samples as well as by statistical means (t-test). In all the samples, T calculated was less than T critical with a significance level of 5%, thus demonstrating that CE is a good alternative for the separation and quantification of polar compounds in plant extracts.
Assessing the stability of arsenic sulfide pigments and influence of the binding media on their degradation by means of spectroscopic and electrochemical techniques Microchem. J. (IF 3.034) Pub Date : 2018-01-06 Marc Vermeulen, Koen Janssens, Jana Sanyova, Vanoushe Rahemi, Chris McGlinchey, Karolien De Wael
In this paper, we used the semiconducting and lightfastness properties of synthetic and mineral arsenic sulfide pigments to study their stability by means of electrochemical and microfadometric techniques. A combination of these techniques shows that in the early stage of the degradation process, amorphous arsenic sulfides are more stable than both crystalline forms, while upon longer exposure time, amorphous pigments will fade more than both mineral pigments, making it less suitable. While the stability study was carried out on unbound pigments, the influence of the organic binder on the relative degradation of the arsenic sulfide pigments was investigated through a multi-analytical approach on pigment/binder mock-up paint samples. For this purpose, the formation of arsenic trioxide was assessed by micro Fourier transform infrared (μ-FTIR) spectroscopy while the influence of the binder on the formation of sulfates was studied by means of synchrotron radiation X-ray near edge structure (μ-XANES). Both techniques elucidate a higher stability of all pigments in gum arabic while the use of egg yolk as binder leads to the most degradation, most likely due to its sulfur-rich composition. In the context of the degradation of arsenic sulfide pigments, other binders such as animal glue, egg white or linseed oil show an intermediate impact.
Polyurethane foam functionalized with phenylfluorone for online preconcentration and determination of copper and cadmium in water samples by flame atomic absorption spectrometry Microchem. J. (IF 3.034) Pub Date : 2018-01-06 Juliana Menezes de Sousa, Marcos Tadeu Couto, Ricardo J. Cassella
In this work, a polyurethane foam (PUF) functionalized with phenylfluorone (PUF-PF) was packed in a minicolumn and used as an on-line preconcentration system for cadmium and copper determination in water samples. The experimental conditions (both chemical and physical) were optimized to achieve the highest sensitivity. A study of possible ion interference on the retention of cadmium and copper was also performed. The enrichment factors obtained were 14 and 16 for copper and cadmium, respectively, using a preconcentration time of 1 min. The proposed system allowed the determination of metals with limits of detection (3σ) of 0.8 and 0.3 μg L− 1 for Cu(II) and Cd(II), respectively. The precision of the procedures was also calculated as 7.6% for Cu(II) (at 25 μg L− 1) and 4.0% for Cd(II) (at 10 μg L− 1). The limits of quantification obtained were 2.6 and 0.8 μg L− 1 for Cu(II) and Cd(II), respectively. Cadmium and copper contents in water samples (from rivers and swimming pools) were determined by applying the proposed procedure. In these samples, recovery tests were conducted in order to evaluate the accuracy of the method; the recovery percentages varied between 83 and 109%.
Evaluation of minerals, toxic elements and bioactive compounds in rose petals (Rosa spp.) using chemometric tools and artificial neural networks Microchem. J. (IF 3.034) Pub Date : 2017-12-20 Ana Maria P. dos Santos, Emmanuelle F.R. Silva, Walter Nei L. dos Santos, Erik G.P. da Silva, Liz O. dos Santos, Bruna R. da S. Santos, Maria C. da S. Sauthier, Wagna P.C. dos Santos
Rose (Rosa spp.) petals have been used for the preparation of new cooking recipes, due to their sensory properties. In this paper were evaluated the micro (Co, Cu, Fe, Mn, Mo, Ni and Zn), macro (Ca, Mg, Na and P) and toxic elements (As, Cd and Cr) of organic cultivation rose by ICP OES and ICP-MS. The bioactive compounds (total phenolics, total flavonoids, total anthocyanins and antioxidant capacity in DPPH) were determined by UV-VIS spectrophotometry. Chemometric tools were used in method optimization, such as full factorial design for acid digestion and Box-Behnken design for total phenolics, in addition to the application of Artificial Neural Networks with Kohonen Neural Network for bioactive compounds. The application of PCA and HCA showed that the mineral composition of rose petal samples had differences between summer and winter. The accuracy of the method was confirmed by the analysis of three certified reference materials: apple leaves (1515), spinach leaves (1570a) and peach leaves (1547), from the National Institute of Standards and Technology (NIST). Digestion efficiency was evaluated by residual carbon content. The developed methods were promising to evaluate the minerals, toxic elements and bioactive compounds in rose petals, and the results indicate that they can be added as a potential nutritional supplement in the human diet.
Modern acrylic paints probed by optical coherence tomography and infrared reflectography Microchem. J. (IF 3.034) Pub Date : 2018-01-04 J. Striova, A. Dal Fovo, V. Fontani, M. Barucci, E. Pampaloni, M. Raffaelli, R. Fontana
Contemporary art is particularly delicate as the synthetic materials used for their realization are of poorer quality and durability than the traditional materials. It follows that the contemporary artworks often require imminent restorations as well as in-depth analytical studies of the constituting materials. The non-invasiveness of the scientific methods is a key issue in the diagnostics of contemporary art because it minimizes the need of sampling. In this respect, the potential of Optical Coherence Tomography (OCT) imaging to probe the internal structure of the commercial acrylic paint layers, as a function of their thickness, was investigated and compared with that of the near infrared (NIR) reflectography. In support of these measurements, micro-profilometry, an interferometric technique with micrometric depth resolution, was used to measure the paint layer thicknesses. We show that for some painted materials there is a limited possibility to visualize the underdrawings, when investigated by both OCT and NIR reflectography. This is owed to either the absorption of the illumination wavelength by the paint layer (Cobalt-based paints) or the multiple photon scattering effect (presence of TiO2).
Development of an electroanalytical method to control quality in fish samples based on an edge plane pyrolytic graphite electrode. Simultaneous determination of hypoxanthine, xanthine and uric acid ☆ Microchem. J. (IF 3.034) Pub Date : 2018-01-02 Gastón Darío Pierini, Sebastian Noel Robledo, María Alicia Zon, María Susana Di Nezio, Adrian Marcelo Granero, Héctor Fernández
Characterization of glaze ceramics from the archaeological site of La Alcazaba, Almería (Spain) Microchem. J. (IF 3.034) Pub Date : 2017-12-26 Inés Ortega-Feliu, Blanca Gómez-Tubío, Yasmina Cáceres, Miguel Ángel Respaldiza
The Alcazaba de Almería is one of the most impressive mediaeval remains in Al-Andalus. Its defensive walls are expression of the economic and strategic relevance of Almeria City during middle Ages. In the course of archaeological excavations in this monumental area, several glazed ceramic remains were found in the palatine area so-called second enclosure. They are dated back between the 10th and the 15th centuries and correspond to small fragments on which different decorative techniques can be identified: green and manganese, green glazed, cuerda seca total, Nazarí Black and White, lustreware and blue and lustre earthenware. Although only seven samples out of 35 selected samples have been analyzed, their interest lie on that they are the first analytical approach to the ceramics of this important archaeological site and the group is representative some of most typical decorative procedures employed in Al-Andalus. The combination of ion beam and nuclear non-destructive analytical techniques performed on these ceramics have allowed the discussion on several aspects of the production technology, as the use of raw materials, and the degradation processes suffered by them. Glaze composition is discussed first. It is characterized by high values of Pb, Sn, Na, K and Mg. Chromophores are identified and some raw materials are discarded (psilomelane for manganese black) or proposed (absolite, skutterudite and trianite for blue). Secondly, the most degraded samples are found to be characterized by high values of Cl, in an inverse relation with the content of Si. The surface of two samples with lustre decorations, one with Cu particles and one with Cu + Ag particles, are studied finding a progressive decrease of Pb in the surface. Finally, the pastes of the samples are characterized by high values of Ca with respect to other ceramics of the area. Similar values are found in ceramics from Manises and Sevilla. The case of a possible imported sample is also discussed.
Homemade 3-carbon electrode system for electrochemical sensing: Application to microRNA detection Microchem. J. (IF 3.034) Pub Date : 2017-12-29 Mariana C.C.G. Carneiro, Felismina T.C. Moreira, Rosa A.F. Dutra, Rúben Fernandes, M. Goreti F. Sales
The homemade production of carbon screen-printed electrodes (C-SPEs) with a three‑carbon electrode system is reported, along with its application in electrochemical sensing. It is highlighted herein as main novelty that a simple carbon ink may be employed in the preparation of the 3-electrode system, including the pseudo-reference electrode, thereby avoiding the addition of silver or other suitable metal and simplify the construction of such devices, reducing costs and time. Screen-printed technology was employed to produce the 3-electrodes and the corresponding electrical paths. This was achieved by the manual application of a commercial carbon ink into a polyvinyl chloride (PVC) substrate allowing the production of > 20 SPEs. The optimization of the SPE assembly was made by univariate mode, until the best electrical features of the electrode-solution interface were achieved. Several electrochemical techniques were used for this purpose, namely cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Raman Spectroscopy and Thermogravimetric Analysis (TGA) were also used for materials and electrode surface characterization. The usefulness of such devices was tested by modifying the working electrode with a sensing layer for microRNA-107, a potential biomarker in Alzheimer's Disease (AD). For this purpose, the surface was functionalized with carboxylic groups, activated by carbodiimide reaction and bound to a suitable oligonucleotide probe containing the complementary sequence. Finally, the microRNA-107 sequence hybridized with its probe, proving the efficiency of the C-SPEs in electrochemical sensing. Overall, this study brings into light the possibility of preparing simple homemade electrodes with a 3‑carbon electrode system that stands out by the low cost, disposability and versatility of the presented platform, holding a great potential for application in point-of-care devices using electrochemical sensing.
Fast derivatization procedure for the analysis of phytoestrogens in soy milk by gas chromatography tandem mass spectrometry Microchem. J. (IF 3.034) Pub Date : 2017-09-28 Barbara Benedetti, Marina Di Carro, Cristiana Mirasole, Emanuele Magi
Ancient and modern paper: Study on ageing and degradation process by means of portable NIR μ-Raman spectroscopy Microchem. J. (IF 3.034) Pub Date : 2017-12-29 Daniele Chiriu, Pier Carlo Ricci, Giancarlo Cappellini, Carlo Maria Carbonaro
For many centuries, paper was considered the main support for recording cultural achievements all over the world. Archives represent the historical memory of our past, and the book conservation represents one main concern since many books and documents kept in libraries and archives are at risk because of their fragility. The use of portable, not destructive technique like NIR μ-Raman spectroscopy represents a valid instrument for monitoring the documentary heritage. In the present study, we investigated the degradation process, associated to the polymers breaking, in order to propose a successful kinetic model for determining the ageing time of cellulose. We compared the calculated results with respect to both experimental samples and literature data, covering a period of seven centuries, from XV to XXI centuries. Proposed model starts directly from Raman spectra, in particular by monitoring the band at 1100 cm− 1 ascribed to C-O-C inter-monomers bond, whose relative intensity is related to the cellulose chain length. We obtained a very good agreement with the experimental data with 8% of accuracy. Finally, with the help of Density Functional Theory (DFT) simulations, we confirmed our model by studying the structure and the grade of cellulose crystallinity in the paper. In particular, the reverse trend of the band at 900 cm− 1, related to the crystallinity grade of the cellulose, and the band at 1100 cm− 1, as a function of the dimer unit cell structure, supported the kinetic model, suggesting a shear stress like effect as the origin of the cellulose chain length decrease.
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