With new advancements in MC-ICP-MS technology, small Cd isotope fractionations in geological processes have attracted more interests in recent years. However, challenges remain in obtaining high-precision Cd isotope data for geological samples with low Cd concentrations and complex matrices. By an improved Cd purification and cleaning resin scheme for low-Cd samples using AGMP-1M resin with >90% Cd recovery, the ratios of trace elements Sn, Mo, Zr, etc. to Cd in the samples, which could potentially jeopardize the accuracy and precision of Cd isotopes analysis under high-sensitivity setup, were less than 0.001 after purification, and the total procedure blank is ≤0.1 ng. Hence, sample size containing 20-30ng Cd can be employed to purify for isotope measurement. Cadmium isotope fractionation (expressed in δ114/110Cd relative to NIST 3108) during column separation and instrument mass bias was corrected for by a 111Cd-113Cd double spike. NIST 3108 was determined at a concentration of 5 -25 ng mL-1 on Neptune Plus (112Cd signal intensity:~640V/ppm) and 25 -50 ng mL-1 on Nu plasma III (112Cd signal intensity:~280V/ppm) MC-ICP-MS equipped with Aridus II/III desolvator for more than one year, with a totally external analytical precision of 0.034‰ (2SD, N=181). The NIST SRM 2711a, NOD-P-1 and GSS-1 were measured at 5, 10, 20, 25 and 50 ng mL-1 level to be 0.532±0.038‰, 0.133±0.038‰ and 0.098±0.027‰, respectively, indicating good accuracy and precision of Cd isotope analysis can be achieved with an injecting sample size as low as 5 ng Cd. Our method can be reliably applied to various geological reference materials (GRMs). The δ114/110Cd of GRMs with relatively high and low Cd concentrations are consistent with previous studies: NOD-A-1(0.124±0.067‰), GSD-11 (-0.274±0.037‰) and BCR-2 (-0.030±0.063‰). The SGR-1b (0.069±0.049‰), GSH-1(-0.337±0.077‰) and others are reported for the first time in this paper. The δ114/110Cd in basalts and stream sediments is relatively homogenous and overlaps with that of the bulk silicate earth (BSE). The δ114/110Cd in shales and soils varies greatly from -0.694 to 0.532‰. Human hair and other animal organs are enriched in light isotopes relative to BSE, whereas terrestrial plants are enriched in heavy isotopes.

The widely applied copper metal is mainly produced by smelting the copper ore, in which fluorine (F) is one of the harmful elements. Therefore, the F content has become a mandatory test index for copper ore. The low excitation efficiency, complex and serious spectral interference makes it difficult to detect F element in copper ore using atomic emission spectroscopy of laser-induced breakdown spectroscopy (LIBS). To address it, the SrF molecular emission bands were investigated to improve the analytical capabilities of LIBS for the determination of trace F in copper ore. The results demonstrated that SrF molecular emission band has a significant accuracy calibration model (R2=0.9933), high detective sensitivity (5 ppm), high analytical accuracy (RMSECV =0.0049 wt.%), and high analytical precision (6.64 wt.%) for detection of F in copper ore. SrF molecular emission bands in LIBS show great potential for F determination in copper ore industry. Furthermore, the mechanism of emission spectrum for SrF molecular was also discussed.

Methodology for the accurate determination of number concentration of inorganic nanoparticles (NP) by single particle inductively coupled plasma mass specrometry (spICP-MS) using the novel dynamic mass flow (DMF) approach is systematically described. Using this method the determination of transport efficiency (TE) is achieved without the need for a reference nanomaterial. The impact of key parameters on the accuracy and uncertainty of the number concentration data obtained with this approach was evaluated. In particular the number of detected NP in the time scan is the major contributing factor to the overall measurement uncertainty. For Au NP of spherical shape with number based concentration in the range of 4.0 x 1012 - 2.0 x 1014 kg-1 (depending on the particle size) a relative expanded uncertainty (k=2) of less than 10% was achieved. This reference methodology was also evaluated for the accurate determination of number concentration of more complex NP namely triethanolamine (TEA)-stabilised TiO2 NP, for which like-for-like NP reference materials are not available. Using a sample mass flow of 0.3578 g min-1 (with an associated uncertainty of 0.0002 g min-1, k=1) the average transport efficiencies for Au NP (in trisodium citrate) and TiO2 NP (in TEA/NaOH) were very similar (7.57 ± 0.13% and 7.77 ± 0.22%, k=1, respectively). Finally the number concentration values for both NP types agreed well with those obtained using particle tracking analysis (PTA), providing evidence for the good agreement between mass-based TE of the sample and NP-based TE with the newly proposed method.

A new method for the determination of bismuth was established by combining ultrasound-assisted dispersive micro solid phase extraction (UA-DMSPE) with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for the first time in this work. Nanometer-sized titanium dioxide (nano-TiO2) was used as adsorbent, and the unpacked extraction pattern simplified the operation procedure. The extraction process was assisted by ultrasound. With the application of slurry sampling, the on-line method combining of UA-DMSPE with TS-FF-AAS was developed. Problems of nebulization associated with previous methods based on the coupling of FAAS and SPME were overcome. The combination significantly improved the analytical performance of the modified FAAS instrument. Under the optimal conditions, the limit of detection (LOD) was 0.34 µg L-1, with sensitivity enhancement factor (EF) of 67. Compared with direct FAAS, the EF was as high as 736. The method was applied to analyze environmental water and geological samples with good agreement with certified values in the standard materials or with values obtained using ICP-MS, which demonstrated its reliability for the determination of traces of Bi in environmental samples. The proposed method provides a promising, simple and low-cost approach to develop a sensitive detection of Bi based on FAAS instrument.

Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is one of the most popular techniques for determining trace element concentrations in sulfides. Due to the lack of matrix-matched standards, standardization of sulfide analyses are usually based on silicate glass calibrant materials. Matrix effects during ns-LA-ICP-MS analyses of Fe-rich sulfides were quantified for many trace elements by comparison of elemental concentrations obtained by LA-ICP-MS and electron microprobe (EPMA) for many synthetic sulfides. The data was used to obtain the fractionation indices (Fi, the ratio between the EPMA- and LA-ICP-MS- determined concentrations of element i) for many elements while considering Fe, Cu and Ni as internal standards. The results show that significant (>15% RD) matrix effects arise during ns-LA-ICP-MS analyses of Ti, Zn, Ge, Se, Mo, Cd, In, Sb, Te, Pb, Bi in sulfides when using Fe as the internal standard. The use of Ni as an internal standard yields on average higher Fi values for most elements, resulting in more pronounced matrix effects for refractory elements and less so for volatile elements, relative to Fe. The use of Cu as an internal standard yields overall more significant matrix effects for volatile elements (i.e. lower Fi values). The Fi values for most elements remain constant with increasing concentrations, and matrix correction factors for these elements can therefore be applied across the ppm to wt.% range. In agreement with previous observations for Fe-rich metals and silicate glasses, the magnitudes of the matrix effects for the various elements are strongly correlated with elemental volatility. This correlation was used to obtain a predictive model for describing Fi for Fe-rich sulfides. The results were used to assess the effects of matrix effects on calculated sulfide liquid - silicate melt partition coefficients derived from experiments. Matrix effects arising through the use of non-matrix-matched standards will result in significant discrepancies between measured and true partition coefficients, the extent mainly depending of the volatility of the element considered. Corrections on ns-LA-ICP-MS derived element concentrations therefore need to be performed to obtain true abundances in the absence of matrix-matched standards.

Gold is traded in virtually every country around the world. Consequently, tracing gold provenance is a difficult but necessary task to ensure a responsible supply chain from deposit to consumer. Measuring the silver content is often the first step in characterizing gold to retrace its origin. In this study, laser-induced breakdown spectroscopy (LIBS) using a handheld instrument was evaluated as a fast and easy method to analyse the silver content in natural gold. Six commercial gold alloys and natural gold from French Guiana were used. Our results demonstrate that a handheld LIBS is relevant to gold traceability and is simple to use in the field. The micron-scale focused laser beam allows in-situ analyses of small gold grains with acceptable reproducibility. Univariate and multivariate regression modelling was performed to assess the best calibration model for quantification of the Ag content. The quadratic univariate model was selected for its good predictive ability, with a coefficient of determination R² of prediction of 0.99 and a mean average error of prediction of 0.36 wt.% Ag. The LIBS analyses of natural gold were compared to the EPMA data using a statistical test that allow distinct gold populations to be discriminated (or matched) and the results indicate it would be suitable for identifying unknown samples. We were able to successfully trace the origin of our “unknown” samples, a promising first step in the goal of delivering a low-cost field-based tool for responsible supply chain management.

With the advent of low dispersion, fast aerosol transport technologies used in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), the need for high-repetition rate lasers became crucial. This work reports on the analytical performance of a LA unit with experimental 500 Hz laser head, interfaced with a quadrupole ICP-MS instrument, and comprising a commercial two-volume ablation chamber (HelEx II) and low-dispersion aerosol transport device (ARIS). The system was tested for potential problems related to particle saturation, elemental fractionation, ionisation efficiency, etc., prior to validation as a high resolution LA-ICP-QMS imaging tool with high mapping rate.

A modified backward elimination approach was proposed for feature selection (FS) to eliminate the redundant and irrelevant features from laser-induced breakdown spectroscopy (LIBS) spectra for rapid classification of Chinese archaeological ceramics. The major elements (Fe, Ca, Si, Al and Mg) of LIBS spectra in the ancient ceramics identified using the National Institute of Standards and Technology (NIST) database. The six different pre-processing methods were used to reduce the error caused by random factors and the influence of various non-target factors on the classification results, which could increase the comparability among the Chinese archaeological ceramics from different dynasties. The input features for random forest (RF) model were selected by a modified backward elimination approach and three assessment criteria of sensitivity, specificity and accuracy from full spectra. LIBS spectra pre-processed by mean centering with the optimal input feature were used to construct a RF classification model for different dynasty ceramics. As indicated by research results, the sensitivity, specificity and accuracy of RF model for the ceramics samples in the test set are 0.9526, 0.9910 and 0.9782, respectively. In this sense, available statistics proved excellent performance of Chinese archaeological ceramics classification. Compared with the predictive result using RF, VI-RF and SBS-RF models, the sensitivity, specificity and accuracy of a modified SBS-RF model are higher than the results by others. The results demonstrate that the proposed algorithm is more efficient to reduce the redundant features, computational time and improve the model performance, and it is a good alternative for rapid analysis in multivariate classification.

In the present work, we describe a sequential U-Pb and Sm-Nd systematics measurement from natural REE-enriched minerals by using a Neptune Plus MC-ICP-MS coupled with a 193nm excimer laser in a single shot . The MC-ICP-MS is equipped with zoom optics lens to bring ion beams into the collector coincidently. The key features allow rapid switching between U-Pb and Sm-Nd collector configuration, which is applied to simultaneously measure the U-Pb age and Sm-Nd isotope of common natural REE-enriched minerals. The robustness and usefulness of the present protocol is investigated by using a series of well-characterized mineral reference materials (monazite, titanite, perovskite) with known U-Pb and Sm-Nd isotopic values, which demonstrate its potential and versatilityin geochemistry and microanalysis for cosmochemistry .

Retraction of ‘Laser produced plasma diagnosis of carcinogenic heavy metals in gallstones’ by Mohammad A. Gondal et al., J. Anal. At. Spectrom., 2016, 31, 506–514.

Retraction of ‘Novel techniques for enhancing the performance of support vector regression chemo-metric in quantitative analysis of LIBS spectra’ by Taoreed Olakunle Owolabi et al., J. Anal. At. Spectrom., 2017, DOI: 10.1039/c7ja00229g.