Method For Trace Element Analysis Research Articles

Secondary fluorescence effect quantification of EPMA analyses of olivine grains embedded in basaltic glass

Trace element analysis of olivine is challenging but vital, since trace elements in olivine can potentially record crystallization conditions and, correspondingly, conditions of magma generation, evolution, and transport dynamics. Electron microprobe analysis (EPMA) is one of the most widely used methods for trace element analysis in olivine for many reasons including but not limited to high-spatial resolution and high precision. EPMA protocols with high-beam currents and long-counting times provide accurate trace element concentrations with low-detection limits. However, these protocols neglect the effect of secondary fluorescence (SF) across phase boundaries, which may lead to fictitious analytical results when analyses are performed near other phases. In these cases, obtaining accurate EPMA data requires correction of SF effects from the adjacent or surrounding phase. In this study, the contents of olivine trace elements Ca, Ni, Mn, Ti, Cr, and Al have been measured in run products of experimental high-temperature studies on mafic magmatic systems consisting of olivine grains embedded in basaltic glass. Olivine grain fragments with known composition, were embedded in basaltic powder, and heated to 1250 °C in 1-atm vertical gas-mixing furnace for a few minutes and quenched. EPMA analyses of the olivine grains before and after the experiments were used to quantify the effect of SF, which was found to be most significant for Ca and Ti, and to a lesser extend for Al, and to depend on the distance from the interface, olivine grain geometry, accelerating voltage, and olivine and glass compositions. By combining our experimental results with systematic SF calculations performed with the Monte Carlo simulation program PENEPMA, analytical expressions that give the apparent Ca, Ti, and Al concentrations due to SF in equant olivine grains embedded in basaltic glass were derived. These equations, which allow for a rapid correction of SF effects, are used to assess the average overestimation due to SF of olivine analyses included in current experimental databases, which might be the source of major discrepancies observed in petrological tools utilizing trace element contents in olivine.

Total vs. Partial Acid Digestion Methods for Trace Element Analysis in Archaeological Sediments

Trace element analysis of sediments from archaeological sites is a valuable method to investigate the anthropic impact and obtain information on the functions of different areas and changes in human activities. One of the most used and effective techniques to carry out this kind of analysis is inductively coupled plasma–mass spectrometry. This technique needs a previous dissolution of the sample by acid attack, but the development of the best method is still a discussed issue. In the present work, total and partial digestion methods were carried out in sediment samples of Cueva de la Cocina (Dos Aguas, Spain), and trace elements were measured and statistically compared. Major elements, soil organic matter amount, and pH data were used to evaluate the main drivers of trace element contents. The differences between the results from the two methods were highlighted. Total digestion is more effective for aluminosilicates and heavy minerals, although the partial digestion results suggested that, in most cases, the difference between the two methods is irrelevant for archaeological interpretations. Furthermore, in some cases, the total digestion of the mineral phases related to the geological contribution could mask the anthropic elemental signals.

Laser ablation inductively coupled plasma mass spectrometry analysis of potash and m-Na-Al glasses in China- using Kernel methods for trace element analysis

Monochrome drawn beads were widely circulated in South and Southeast Asia as early as the second century BC. This article aims to identify the glass beads unearthed from different sites in China and discuss their possible sources. Twenty-seven mineral soda alumina (m-Na-Al) glass and eighty-seven potash glass beads unearthed in different provinces in China were analysed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry. The trace element analysis through Multivariate Kernel Density Estimation and Maximum Mean Discrepancy indicates the silica sources of m-Na-Al glass and most of the potash glass unearthed from Guangxi are identical. They were presumably produced somewhere in northeastern India or Southeast Asia and exported through the Maritime Silk Road. The silica sources of m-Na-Al glass in Henan and the rest of the potash glasses are geologically close. They were likely produced in southern India or Sri Lanka and exported through the North and Southwest Silk Roads. Future research on isotopic analysis will reveal more information about primary/secondary glass production in China, South and Southeast Asia.

Simultaneous determination of mercury, cadmium and lead in fish sauce using Diffusive Gradients in Thin-films technique

Fish sauce is a popular seasoning liquid originating from southeastern Asian cuisine, consisting of fermented fish, salt and additional ingredients. Fish can contain high amounts of metals, some of which are hazardous for human health. Therefore, authorities responsible for food safety and quality should monitor the levels of these contaminants in fish and fish deviated products. In this work, the passive sampling technique of Diffusive Gradients in Thin-films (DGT) containing Chelex-100 and Purolite S924 resin gels, is used for the determination of dissolved mercury (Hg), cadmium (Cd) and lead (Pb) in fish sauce. The DGT performance test showed linear accumulation of Hg, Cd and Pb on the binding gels versus deployment time. A wide range of pH and salt concentration did not affect the performance of the DGT. The effective diffusion coefficients of Hg, Cd and Pb in diffusive gels were determined by applying a series of deployments in fish sauce solution. Besides the direct sampling with the DGT technique, fish sauce samples were also digested using a microwave oven. Analyses of DGT and microwave oven digested samples were performed with Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). Both methods were then used for the analysis of fish sauces from local retail stores. Due to the preconcentration ability of DGT, lower detection limits of Hg, Cd and Pb could be achieved compared to the microwave digestion method. The DGT technique offers a more sensitive method for trace element analysis in complex food matrices.

Measurement and analysis of photonuclear reactions on thick target samples of biological importance

A novel method for quantification of trace elements in herbal samples using photon activation analysis is reported. Seven trace elements have been detected and their concentrations have been estimated from residue yields after the photo-nuclear reaction. This method can complement the conventional neutron activation analysis for trace elemental detection. The data is useful for setting referral standards for quality assurance of herbs and herbal formulations commercially available for therapeutic purposes. This is a relatively simple, novel and sensitive method for trace elemental analysis which can be scaled to suit industrial and statutory requirements of standardization and quality control.

Revisited digestion methods for trace element analysis in human hair

BackgroundThe human hair is a potential material for assessing the exposure to environmental contaminants and tracing human mobility. Although various digestion methods have been proposed for determining trace elements in the human hair, there is no consensus about the best method among them yet.FindingsWe examined five different methods in order to determine the best method yielding the most accurate and precise data of trace elements in the human hair using two certified reference human hairs (IAEA085 and IAEA086) under controlled conditions (temperature, the volume of hydrogen peroxide (H2O2), and the number of digestion). Results showed that a high temperature of 160 °C yields better recovery rates than a low temperature of 70 °C. Furthermore, the additional input of H2O2 increases the recovery rate from 90 to 102%, and the two-time digestion also promotes the recovery rate.ConclusionsThis study suggests that although the combination of high temperature (160 °C), high volume of H2O2 (0.4 mL), and two-time digestion yields the most accurate and precise data of trace elements in the human hair, the digestion method should be carefully selected depending on the content of organometallic cation.

Effects of Mechanical Vibration during Drying of Solution Sample in Enhancing the Sensitivity of Total Reflection X-ray Fluorescence Analysis.

This study describes a sample preparation method for trace element analysis using total reflection X-ray fluorescence analysis. The procedure of this method is as follows: 1) a hydrophobic-coated sample holder whose hydrophobic film at around the center of the surface is partially dissolved by acetone is prepared; 2) a droplet of a sample solution is dropped on the sample holder; and 3) the sample droplet is heated and dried while vibrating it. This sample preparation method is effective for reducing the size of the dry residue of the sample solution and suppressing the coffee-ring formation. Furthermore, this method leads to an enhancement in the intensity of an X-ray fluorescence line from an analyte element in the sample residue. In this study, this sample preparation method led to an improvement in the detection limit for vanadium in commercially available bottled drinking water.

Electrospray deposition followed by laser-induced breakdown spectroscopy (ESD-LIBS): a new method for trace elemental analysis of aqueous samples

Hyphenation of electrospray deposition with laser-induced breakdown spectroscopy as an alternative approach for sensitive elemental analysis of liquids with high possibilities of automation.

Rapid measurement of strontium in speleothems using core-scanning micro X-ray fluorescence

Speleothem trace element ratios such as Mg/Ca and Sr/Ca are increasingly used in speleothem paleoclimatology as a supplement to stable oxygen and carbon isotope ratios as proxies for past variability in the hydrologic system. Using multiple proxies together allows for a better understanding of both the local and distal hydrologic changes recorded in speleothem chemistry, and therefore of changes in past rainfall. Despite the potential benefits, trace element analysis of speleothems has yet to become widespread, which is likely due to the significant time and costs required by traditional trace element analytical techniques. In this study, we present an in-depth investigation into a rapid, relatively non-destructive and competitively priced technique for measuring Sr/Ca in speleothems: Core-Scanning micro X-ray Fluorescence (CS-μXRF).We show that CS-μXRF reliably and precisely records Sr concentration in speleothems. Ratioed to near-stoichiometric Ca, the Sr/Ca ratio accounts for variations in beam strength and machine settings, producing a more reliable reported measurement for both intra- and inter-run comparisons. CS-μXRF compares favorably with more conventional trace element procedures such as Quadrupole ICP-MS and ICP-AES, giving confidence in the ability of CS-μXRF to produce paleoclimatologically significant Sr/Ca results. We also identify secondary issues relating to speleothem crystallinity, the dominance of Ca spectral peaks, and comparatively lower energy X-rays that can interfere with precise CS-μXRF analyses. If these can be overcome then CS-μXRF may provide an even more useful method of trace element analysis in speleothem studies.

Elemental analysis of the thyroid by laser induced breakdown spectroscopy.

The thyroid is an important hormone regulation organ. Laser induced breakdown spectroscopy (LIBS) is developed to assess iodine and other essential elements in the thyroid (of rats). Subjects are administered 0.05% iodine water for 0, 6, and 12 days before the thyroid is extracted. Pronounced iodine, sodium, calcium, and potassium emissions are observed at approximately 746, 589, 395/422, and 766/770 nm, respectively. Iodine emission is surprisingly highest in 0 day subjects, lowest after 6 days, and recovers by 12 days. This follows the Wolff-Chaikoff effect as ingestion of excess iodine reduces thyroid iodine and iodine is essential for hormone production. LIBS is a promising method for trace elemental analysis of the thyroid.

Micro X‐ray fluorescence (μXRF) line scanning on Cretaceous rudist bivalves: A new method for reproducible trace element profiles in bivalve calcite

AbstractThe reconstruction of palaeoclimate on a sub‐annual scale requires the measurement of chemical proxies in fossil material at a high spatial resolution. While various methods for trace element analysis on the micrometre scale are available, they are usually destructive to the sample or not widely accessible. This study evaluates the performance of a table‐top micro X‐ray fluorescence scanner in obtaining reproducible trace element profiles on bivalve calcite. Standard calibration and repeatability tests demonstrate the robustness of results obtained with this new generation micro X‐ray fluorescence device that uses a comparatively high excitation energy of 30 W. Results show that elemental abundances measured using this fast, readily accessible and non‐destructive analytical set‐up are reproducible on the μg g−1 level, and therefore suitable for the analysis of the abundance of commonly studied elements in bivalve calcite (for example, Sr, Mn and Fe). Spectra obtained in this study show considerable improvement in terms of signal to noise ratio compared to earlier table‐top micro X‐ray fluorescence studies. Reliability of the measurements is tested using a conservative detection and quantification limit. Count rates of Ca are used to check for point measurements disturbed by irregularities on the sample surface. Furthermore, the method allows semi‐quantitative two‐dimensional element mapping, which is a convenient tool for the detection of diagenetic alteration in fossil samples. The method reveals records of Sr/Ca, Fe/Ca and Mn/Ca ratios in a Late Campanian Vaccinites vesiculosus shell, with Sr/Ca ratios showing a trend opposite to Mn/Ca and Fe/Ca. Resulting trace element records are discussed in terms of seasonal cyclicity in the Late Cretaceous and diagenetic alteration of the fossil shell.

규산염 암석의 알칼리 용융 유리원판에 대한 LA-ICP-MS 전암 미량원소 분석법 평가

알칼리 용융법으로 제조한 규산염 암석 참조물질(JR-3, JG-3, JGb-1, JB-1b) 유리원판에 대하여 레이저 삭마-유도결합 플라즈마 질량분석법(LA-ICP-MS)으로 미량원소를 분석한 결과의 신뢰도를 평가하였다. 희토류 원소를 포함하는 28개 원소 분석결과시 암석내 농도가 10 ppm 이상인 경우에는 측정의 상대표준편차(RSD)가 7% 이하이었으며, 10 ppm이하의 농도에서는 RSD가 다소 증가하기도 하지만 25%를 넘지는 않았다. 동일한 암석 참조물질로부터 이전에 보고된 분석자료의 평균과 비교하면 대부분의 경우 최대 10% 내외의 편차로 잘 일치하는 만족스러운 결과를 나타낸다. 알칼리 용융 유리원판을 이용한 LA-ICP-MS 분석법은 용액 ICP-MS 분석법에 비하여 전처리 과정을 대폭 줄이고 빠른 시간 내에 비교적 높은 정밀도로 고철질에서 규장질까지 대부분 암석의 미량원소를 분석할 수 있는 방법으로 평가된다. Using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we evaluated the reliability of trace element abundance data measured from the silicate rock references of JR-3, JG-3, JGb-1 and JB-1b using glass discs made by alkali fusion. For 28 elements including rare earth elements, relative standard deviations (RSD) are better than 7% in case when the concentrations of the elements in the rock samples are greater than 10 ppm. However, RSD shows somewhat increased values for the concentrations less than 10 ppm, but never exceeds 25%. Compared with previously reported averages of the compiled abundance data, our data display satisfactory results for the most cases with differences less than 10%. We suggest that LA-ICP-MS analysis using fused glass beads is a reliable, precise and time-saving method of trace element analysis for the silicate rocks spanning from mafic to felsic compositions.

Evaluation of a rapid, effective sample digestion method for trace element analysis of granitoid samples containing acid-resistant minerals: Alkali fusion after acid digestion

Evaluation of a rapid, effective sample digestion method for trace element analysis of granitoid samples containing acid-resistant minerals: Alkali fusion after acid digestion

Ultra-trace Rb detection with degenerate four-wave mixing in a graphite furnace

Degenerate four-wave mixing (DFWM) is employed to detect rubidium (Rb) in a graphite furnace atomizer as a versatile spectroscopic method for trace element analysis at high spectral resolution. In order to further reduce the detection limit for ultra-trace Rb detection, HNO3, NaNO3, KNO3 and CsNO3 are used as chemical modifiers and the corresponding effects on the Rb DFWM signal are investigated. The experimental results show that NO3− has an enhancement, while the effects of the metals mainly depend on their ionization potentials. Among these chemical modifiers, CsNO3 can significantly enhance the Rb DFWM signal intensity. Using CsNO3, the detection limit was reduced from 7.02 ng mL−1 to 0.90 ng mL−1. This investigation indicates that nitrates, especially those with metallic ions of lower ionization potential can effectively enhance the DFWM signal intensity and reduce the detection limit, which is of special significance in ultra-trace element detection.

Elemental analysis by surface-enhanced Laser-Induced Breakdown Spectroscopy combined with liquid–liquid microextraction

In this work, the possibility of using Laser-Induced Breakdown Spectrometry (LIBS) combined with liquid–liquid microextraction techniques is evaluated as a simple and fast method for trace elemental analysis. Two different strategies for LIBS analysis of manganese contained in microdroplets of extraction solvent (Triton X-114) are studied: (i) analysis by direct laser irradiation of microdroplets; and (ii) analysis by laser irradiation of microdroplets dried on metallic substrates (surface-enhanced LIBS — SENLIBS). Experiments were carried out using synthetic samples with different concentrations of manganese in a 10% w/w Triton X-114 matrix. The analysis by direct laser irradiation of microdroplets showed low precision, sensitivity and poor linearity across the concentration range evaluated (R2<0.95). On the other hand, the SENLIBS method of analysis improved the sensitivity, the precision and the linearity of the calibration curve with respect to the direct analysis of microdroplets. In comparison with experimental results obtained by direct analysis, SENLIBS also allowed several replicate measurements to be carried out in a single microdroplet. The limit of detection obtained was 6μgg−1 of Mn.

Modification and preservation of environmental signals in speleothems

Speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system. However, the climatological meaning of many speleothem records cannot be interpreted unequivocally; this is particularly so for more subtle shifts and shorter time periods, but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward. An explicit description of speleothem records as time series draws attention to the nature and importance of the signal filtering processes by which the weather, the seasons, and longer-term climatic and other environmental fluctuations become encoded in speleothems. We distinguish five sources of variation that influence speleothem geochemistry, i.e. atmospheric, vegetation/soil, karstic aquifer, primary speleothem crystal growth and secondary alteration, and give specific examples of their influence. The direct role of climate diminishes progressively through these five factors. We identify and review a number of processes identified in recent and current work that bear significantly on the conventional interpretation of speleothem records, for example: (1) speleothem geochemistry can vary seasonally and hence a research need is to establish the proportion of growth attributable to different seasons and whether this varies over time; (2) whereas there has traditionally been a focus on monthly mean δ 18O data of atmospheric moisture, current work emphasizes the importance of understanding the synoptic processes that lead to characteristic isotope signals, since changing relative abundance of different weather types might control their variation on the longer-term; (3) the ecosystem and soil zone overlying the cave fundamentally imprint the carbon and trace element signals and can show characteristic variations with time; (4) new modelling on aquifer plumbing allows quantification of the effects of aquifer mixing; (5) recent work has emphasized the importance and seasonal variability of CO 2-degassing leading to calcite precipitation upflow of a depositional site on carbon isotope and trace element composition of speleothems; (6) although much is known about the chemical partitioning between water and stalagmites, variability in relation to crystal growth mechanisms and kinetics is a research frontier; (7) aragonite is susceptible to conversion to calcite with major loss of chemical information, but the controls on the rate of this process are obscure. Analytical factors are critical in generating high-resolution speleothem records. A variety of methods of trace element analysis is available, but standardization is a common problem with the most rapid methods. New stable isotope data on Irish stalagmite CC3 compares rapid laser-ablation techniques with the conventional analysis of micromilled powders and ion microprobe methods. A high degree of comparability between techniques for δ 18O is found on the millimeter to centimeter scale, but a previously described high-amplitude oxygen isotope excursion around 8.3 ka is identified as an analytical artefact related to fractionation of the laser-analysis associated with sample cracking. High-frequency variability of not less than 0.5‰ may be an inherent feature of speleothem δ 18O records.

Trace analysis of rubidium hyperfine structure in a flame atomizer using sub-Doppler laser wave-mixing spectroscopy.

Nonlinear laser wave mixing is a versatile spectroscopic method for trace elemental analysis at high spectral resolution. Sub-Doppler spectral resolution allows isotope and hyperfine structure measurements of some of the elements even when using a room-pressure analytical flame (i.e., sub-Doppler but Lorentzian broadened spectra). A non-planar wave-mixing optical setup offers some advantages as compared to the conventional planar wave-mixing setup including better signal collection efficiency and easier optical alignment. Using our absorption-based wave mixing, a detection limit of 0.05 ng/mL (i.e., 50 parts-per-trillion) is reported for Rb in an air/acetylene flame, while still maintaining sub-Doppler spectral resolution for the infrared 780.0-nm Rb transition line.

Trace element analysis of blood samples from mentally challenged children by PIXE

The accelerator based ion beam analysis method of proton induced X-ray emission (PIXE) has been used for analysing up to 14 elements in the blood serum of patients, collected from rehabilitation centres for the mentally retarded and from Medical College Hospital, Coimbatore, Tamil Nadu, India. The experimental subjects of the different groups displayed significant variations in their levels of certain trace elements such as zinc, iron, copper, phosphorus, chlorine, and rubidium. The results are compared with those of healthy control subjects and are discussed in detail in this paper. Hence, PIXE as a method of trace element analysis can be used to determine trace element content in mentally challenged patients.

Total reflection X-ray fluorescence: A technique for trace element analysis in materials

Total Reflection X-ray Fluorescence (TXRF) is a variant of Energy dispersive X-ray Fluorescence (EDXRF). It is a comparatively new method of trace element analysis and finds its application in various research areas of material development and processing. The versatility of TXRF is due to (i.) requirement of very less amount of sample (ii.) its capability to analyse very low concentrations and (iii.) capability of analysing surface and shallow layers up to a depth of few nanometers profiling up to few nanometers depth in materials. Presence of impurities in semiconductor wafers affects the quality of the wafer significantly. Analysis of thin wafers is one of the several applications of TXRF where no other technique can compete with it. In the present paper the principle, advantages and some applications of this technique are briefly summarised.

Distribution of an 18 kDa-selenoprotein in several tissues of the rat

By combining methods for trace element analysis, tracer techniques and various biochemical and electrophoretical procedures, information on the characteristics of an 18 kDa-selenoprotein was obtained. By labeling of rats in vivo with [ 75Se]-selenite and gel electrophoretic separation of the proteins in tissues and subcellular fractions, a larger number of selenium-containing proteins could be distinguished. In most of the tissues investigated a labeled 18 kDa-band was present. After co-electrophoresis of the 18 kDa-bands from kidney, liver and brain we found that they all migrated in the same way. Using ultracentrifugational fractionation the 18 kDa-band was localized in the mitochondrial and microsomal membranes. Two-dimensional electrophoresis showed that it consists of a single selenium-containing protein with an isoelectric point of about 4.9–5.0. By means of proteolytic cleavage of the 18 kDa-protein and separation of its peptides by tricine-SDS-PAGE six selenium-containing peptides with molecular masses of 17, 16, 14, 12, 10, and 8 kDa were detected. After electrophoretic separation of the mitochondrial and/or microsomal proteins and acid hydrolysis of the electroeluted protein its amino acid composition was analyzed by RP-HPLC. In this way it was shown that selenium is present in the 18 kDa-protein in form of selenocysteine which is a characteristic of a genetically encoded selenoprotein.