Use of chelating resins and inductively coupled plasma mass spectrometry for simultaneous determination of trace and major elements in small volumes of saline water samples

For some saline environments (e.g. deeply percolating groundwater, interstitial water in marine sediments, water sample collected after several steps of fractionation) the volume of water sample available is limited. A technique is presented which enables simultaneous determination of major and trace elements after preconcentration of only 60 mL sample on chelating resins. Chelex-100 and Chelamine were used for the preconcentration of trace elements (Cd, Cu, Pb, Zn, Sc) and rare earth elements (La, Ce, Nd, Yb) from saline water before their measurement by inductively coupled plasma mass spectrometry. Retention of the major elements (Na, Ca, Mg) by the Chelamine resin was lower than by Chelex; this enabled their direct measurement in the solution after passage through the resin column. For trace metal recoveries both resins yield the same mass balance. Only Chelex resin enabled the quantitative recovery of rare earth elements. The major elements, trace metals and rare earth elements cannot be measured after passage through one resin only. The protocol proposes the initial use of Chelamine for measurement of trace and major elements and then passage the same sample through the Chelex resin for determination of the rare earth elements. The detection limit ranged from 1 to 12 pg mL^–1. At concentrations of 1 ng mL^–1 of trace metals and REE spiked in coastal water the precision for 10 replicates was in the range of 0.3–3.4% (RSD). The accuracy of the method was demonstrated by analyzing two standard reference waters, SLRS-3 and CASS-3.     

Simultaneous determination of major,minor and trace elements in biocarbonates by inductively coupled plasma mass spectrometry

A method was developed for simultaneous determination of major (Ca), minor (Mg and Sr) and trace (Ba and U) elements in biocarbonates by inductively coupled plasma mass spectrometry (ICP-MS). The method precision (RSD%) is 0.73% for Ca, 0.77% for Mg, 0.59% for Sr, 2.02% for Ba, 1.13% for U, 0.67% for Mg/Ca, 0.27% for Sr/Ca, 2.06% for Ba/Ca and 1.23% for U/Ca. The ratio precision suggests that ICP-MS is satisfactory for obtaining multi-ratio data from biocarbonates. This technique was applied to 67 continuous coral samples.     

Microwave digestion methods for the determination of trace elements in brain and liver samples by inductively coupled plasma mass spectrometry

Two microwave digestion systems (open-focused and closed-pressurized) were tested for the mineralization of human brain and bovine liver (NIST SRM 1577a) as dissolution steps prior to the determination of 16 trace elements (Bi, Cd, Co, Cs, Cu, Fe, Hg, Mn, Mo, Pb, Rb, Sb, Sn, Sr, Tl, and Zn) by inductively coupled plasma mass spectrometry (ICP-MS). Digestion parameters (mass of sample, digestion mixture, and power/time steps) were optimized using temperature and pressure sensors. Digestions with the open-focused microwave system require larger volumes of conc. HNO₃ and 30% H₂O₂ than digestions with the closed-pressurized system. Both systems produce correct results for the bovine liver samples. The concentrations obtained for the digests of the open-focused system tend to be less precise than the concentrations from the closed-pressurized digests. Because the open-focused digests must be diluted to 50 mL to bring the acid concentration to 0.7–2.0 mol/L required by the ICP-MS (closed-pressurized digests need to be diluted to only 20 mL), the detection limits for the system with the open-focused digestion are higher than for the system with the closed-pressurized digestor. The open-focused digestor cannot handle more than 150 mg brain tissue, whereas the closed-pressurized system can mineralize 470 mg. The latter method gave better results with brain tissue than the open-focused system. The preparation of brain tissue as reference material for the determination of trace elements in brain samples is described.     

Use of a microcolumn packed with modified carbon nanofibers coupled with inductively coupled plasma mass spectrometry for simultaneous on-line preconcentration and determination of trace rare earth elements in biological samples

In this work, a new method was developed for the determination of trace rare earth elements (REEs) in biological samples by inductively coupled plasma mass spectrometry (ICP-MS) after preconcentration on a microcolumn packed with modified carbon nanofibers (CNFs). CNFs oxidized with nitric acid have been proved to possess an exceptional adsorption capability for REEs due to their surface functionalization. The effects of the experimental parameters, including pH, sample flow rate and volume, elution solution and interfering ions, on the recoveries of the analytes have been investigated systematically. A 100-fold enrichment factor was obtained. The adsorption capacity of CNFs was found to be 18.1, 19.3, 23.6, 17.6, 22.3 and 19.5 mg/g for La, Ce, Sm, Eu, Dy and Y, respectively. Under the optimum conditions, the detection limits of this method ranged from 0.2 pg/mL (Dy) to 1.2 pg/mL (Ce) with an enrichment factor of 15-fold, and the relative standard deviations (RSDs) for the determination of REEs at the 1.0 ng/mL level were less than 4% (n = 9). This method was applied to the analysis of trace REEs in a real sample of human hair with recoveries of 95-115%. In order to validate the proposed method, a certified reference material of human hair (GBW 07601) was analyzed with satisfactory results.     

Determination of trace elements in geological samples by laser ablation inductively coupled plasma mass spectrometry

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for the sensitive multi-element analysis of traces and ultra-traces in geological samples. In order to prepare homogeneous targets the powdered geological samples were melted together with a lithium-borate mixture (90% Li₂B₄O₇, 10% LiBO₂) in a muffle furnace at 1050 °C. The quantification of the analysis results was carried out using the BCR-2G and BM standard reference material (SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most of the elements, whereas the relative standard deviation (RSD) of the determination (N = 3) of the concentration was 5–20%. The analysis results of LA-ICP-MS for various geological samples are in agreement with those of other methods. Received 31 March 1999 / Revised: 26 May 1999 / Accepted: 31 May 1999     

Determination of trace elements in geological samples by laser ablation inductively coupled plasma mass spectrometry

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for the sensitive multi-element analysis of traces and ultra-traces in geological samples. In order to prepare homogeneous targets the powdered geological samples were melted together with a lithium-borate mixture (90% Li₂B₄O₇, 10% LiBO₂) in a muffle furnace at 1050?°C. The quantification of the analysis results was carried out using the BCR-2G and BM standard reference material (SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most of the elements, whereas the relative standard deviation (RSD) of the determination (N = 3) of the concentration was 5–20%. The analysis results of LA-ICP-MS for various geological samples are in agreement with those of other methods.     

Microwave digestion methods for the determination of trace elements in brain and liver samples by inductively coupled plasma mass spectrometry

Two microwave digestion systems (open-focused and closed-pressurized) were tested for the mineralization of human brain and bovine liver (NIST SRM 1577a) as dissolution steps prior to the determination of 16 trace elements (Bi, Cd, Co, Cs, Cu, Fe, Hg, Mn, Mo, Pb, Rb, Sb, Sn, Sr, Tl, and Zn) by inductively coupled plasma mass spectrometry (ICP-MS). Digestion parameters (mass of sample, digestion mixture, and power/time steps) were optimized using temperature and pressure sensors. Digestions with the open-focused microwave system require larger volumes of conc. HNO(3) and 30% H(2)O(2) than digestions with the closed-pressurized system. Both systems produce correct results for the bovine liver samples. The concentrations obtained for the digests of the open-focused system tend to be less precise than the concentrations from the "closed-pressurized" digests. Because the "open-focused" digests must be diluted to 50 mL to bring the acid concentration to 0.7-2.0 mol/L required by the ICP-MS (closed-pressurized digests need to be diluted to only 20 mL), the detection limits for the system with the open-focused digestion are higher than for the system with the closed-pressurized digestor. The open-focused digestor cannot handle more than 150 mg brain tissue, whereas the closed-pressurized system can mineralize 470 mg. The latter method gave better results with brain tissue than the open-focused system. The preparation of brain tissue as reference material for the determination of trace elements in brain samples is described.     

Microwave assisted digestion of atmospheric aerosol samples followed by inductively coupled plasma mass spectrometry determination of trace elements

A microwave digestion method in a closed vessel was developed for the determination of trace metals in atmospheric aerosols using inductively coupled plasma mass spectrometry (ICP-MS). A recovery study for the elements V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sb, and Pb was conducted using multi-elemental standard solutions, NIST 1633b Trace Elements in Coal Fly Ash, and NIST 1648 Urban Particulate Matter. A simple digestion method using only HNO₃/H₂O₂ gave good recoveries (90%–108%) for all elements except Cr in SRM 1648, but yielded low recoveries for SRM 1633b. A more robust method using HNO₃/H₂O₂/HF/H₃BO₃ yielded higher recoveries (82%–¶103%) for the lighter elements (V – Zn) in SRM 1633b, and improved the Cr recovery in SRM 1648, but decreased the Se recovery in both SRMs. A comparative analysis of aerosol samples obtained at a remote mountain location Nathiagali, Pakistan (2.5 km above mean sea level), and Mayville, New York, downwind from the highly industrialized Midwestern United States, was carried out using Instrumental Neutron Activation Analysis (INAA) for the elements Cr, Mn, Fe, Co, Zn, As, Se, and Sb. The simple digestion method yielded excellent agreement for Cr, Fe, Zn, As, Se, and Sb, with slopes of the ICP-MS vs. INAA regressions of 0.90–1.00 and R² values of 0.96–1.00. The regressions for Mn and Co had slopes of 0.82 and 0.84 with R² values of 0.83 and 0.82, respectively. Addition of HF/H₃BO₃ did not improve the correlation for any of the elements and degraded the precision somewhat. The technique provides sensitivity and accuracy for trace elements in relatively small aerosol samples used in atmospheric chemistry studies related to SO₂ oxidation in cloud droplets. The ability to determine concentrations of a very large number of elements from a single analysis will permit source apportionment of various trace pollutants and hence strategies to control the sources of air pollution. This is particularly important as the health effects of particulate matter are increasingly recognized.     

Microwave assisted digestion of atmospheric aerosol samples followed by inductively coupled plasma mass spectrometry determination of trace elements

A microwave digestion method in a closed vessel was developed for the determination of trace metals in atmospheric aerosols using inductively coupled plasma mass spectrometry (ICP-MS). A recovery study for the elements V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sb, and Pb was conducted using multi-elemental standard solutions, NIST 1633b Trace Elements in Coal Fly Ash, and NIST 1648 Urban Particulate Matter. A simple digestion method using only HNO3/H2O2 gave good recoveries (90%-108%) for all elements except Cr in SRM 1648, but yielded low recoveries for SRM 1633b. A more robust method using HNO3/H2O2/HF/H3BO3 yielded higher recoveries (82%-103%) for the lighter elements (V-Zn) in SRM 1633b, and improved the Cr recovery in SRM 1648, but decreased the Se recovery in both SRMs. A comparative analysis of aerosol samples obtained at a remote mountain location Nathiagali, Pakistan (2.5 km above mean sea level), and Mayville, New York, downwind from the highly industrialized Midwestern United States, was carried out using Instrumental Neutron Activation Analysis (INAA) for the elements Cr, Mn, Fe, Co, Zn, As, Se, and Sb. The simple digestion method yielded excellent agreement for Cr, Fe, Zn, As, Se, and Sb, with slopes of the ICP-MS vs. INAA regressions of 0.90-1.00 and R2 values of 0.96-1.00. The regressions for Mn and Co had slopes of 0.82 and 0.84 with R2 values of 0.83 and 0.82, respectively. Addition of HF/H3BO3 did not improve the correlation for any of the elements and degraded the precision somewhat. The technique provides sensitivity and accuracy for trace elements in relatively small aerosol samples used in atmospheric chemistry studies related to SO2 oxidation in cloud droplets. The ability to determine concentrations of a very large number of elements from a single analysis will permit source apportionment of various trace pollutants and hence strategies to control the sources of air pollution. This is particularly important as the health effects of particulate matter are increasingly recognized.     

Simultaneous determination of major to ultratrace elements in geological samples by fusion-dissolution and inductively coupled plasma mass spectrometry techniques

A method has been developed for the simultaneous quantification of major to ultratrace elements in geological samples using quadrupole ICP-MS techniques. The sample preparation involves fusion with LiBO₂ and dilution in HNO₃-HF which allows complete decomposition of refractory minerals and quantification of the elements of interest. The effects of high Total Dissolved Solids (TDS) and Li in the solution are minimized using a matrix-tolerant interface and conditioning the instrument with LiBO₂ solution. The signal drift is moreover controlled using conventional internal standards and specific Drift Correction Standards (DCS). A key issue of the technique is the external calibration using selected Certified Reference Materials (CRM). Depending on the sample type and analytes of interest three optimized programmable modes are used sequentially: Standard, Collision Cell (CCT) and Kinetic Energy Discrimination (KED) mode. The method allows to quantify more than 40 elements in concentrations from tens-of-percent to <0.1 ppm levels during a single experiment. The method has been validated through the analysis of different CRMs with recovery factors of ca. 100% and typical 2σ errors of <10%.     

Determination of trace elements in granites by inductively coupled plasma mass spectrometry

Proposed is a simple and reliable method for the dissolution of granite and the determination of 38 elements by inductively coupled plasma mass spectrometry. One hundred milligrams of sample are digested with 1 ml of HF and 0.5 ml of HNO(3) in screw top PTFE-lined stainless steel bombs at 190 degrees C for 12 h. Insoluble residues are dissolved using 8 ml of 40% HNO(3) (v/v) heated to 110 degrees C for 3 h. Six granite standard reference materials (GSR-1, JG-2, G-2, NIM-G, SG-3, SG-1a) were studied. Analytical calibration was accomplished using aqueous standard solutions. Rhodium was used as an internal standard to correct for matrix effects and instrument drift. We report data for: Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cs, Ba, Hf, Ta, W, Pb, Th, U and 14 of the rare earth elements. The recoveries for most of these elements in granite ranged from 90 to 110%.     

Radionuclide determination in environmental samples by inductively coupled plasma mass spectrometry

The determination of naturally occurring and anthropogenic radionuclides in the environment by inductively coupled plasma mass spectrometry has gained recognition over the last fifteen years, relative to radiometric techniques, as the result of improvement in instrumental performance, sample introduction equipment, and sample preparation. With the increase in instrumental sensitivity, it is now possible to measure ultratrace levels (fg range) of many radioisotopes, including those with half-lives between 1 and 1000 years, without requiring very complex sample pre-concentration schemes. However, the identification and quantification of radioisotopes in environmental matrices is still hampered by a variety of analytical issues such as spectral (both atomic and molecular ions) and non-spectral (matrix effect) interferences and instrumental limitations (e.g., abundance sensitivity).The scope of this review is to highlight recent analytical progress and issues associated with the determination of radionuclides by inductively coupled plasma mass spectrometry. The impact of interferences, instrumental limitations (e.g., degree of ionization, abundance sensitivity, detection limits) and low sample-to-plasma transfer efficiency on the measurement of radionuclides by inductively coupled plasma mass spectrometry will be described. Solutions that overcome these issues will be discussed, highlighting their pros and cons and assessing their impact on the measurement of environmental radioactivity. Among the solutions proposed, mass and chemical resolution through the use of sector-field instruments and chemical reactions/collisions in a pressurized cell, respectively, will be described. Other methods, such as unique sample introduction equipment (e.g., laser ablation, electrothermal vaporisation, high efficiency nebulization) and instrumental modifications/optimizations (e.g., instrumental vacuum, radiofrequency power, guard electrode) that improve sensitivity and performance will also be examined.     

Open-channel chip-based solid-phase extraction combined with inductively coupled plasma-mass spectrometry for online determination of trace elements in volume-limited saline samples

In this study, we used an automated online chip-based solid-phase extraction (SPE)-inductively coupled plasma-mass spectrometry (ICP-MS) system for analyzing trace elements in small-volume saline samples (～15 μL). The proposed method involved the adsorption of trace metal ions in the interior of a functionalized poly(methyl methacrylate) (PMMA) channel in order to separate these ions from saline matrices. The adsorption of transition metal ions was presumably dominated by the surface complexation between the carboxylate moieties in the interior of the PMMA channel and the metal ions, which facilitated the formation of metal-carboxylate complexes. The components of the proposed online analytical system used for the simultaneous detection of multiple trace metals in saline samples involved microdialysis (MD) sampling, an established chip-based SPE procedure, and ICP-MS. The SPE-ICP-MS hyphenated system was optimized, and then, the analytical reliability of this system was further confirmed by using it to analyze the certified reference materials-SRM 2670 (human urine) and SRM 1643e (artificial saline water). The satisfactory analytical results indicated that the proposed on-chip SPE device could be readily used as an interface for coupling the MD probe with the ICP-MS system. The dramatically reduced consumption of chemicals and "hands-on" manipulations enabled the realization of a simplified and relatively clean procedure with extremely low detection limits in the range of 5.86-76.91 ng L(-1) for detecting Mn, Co, Ni, Cu, and Pb in 15-μL samples by ICP-MS. The effectiveness of an online MD-chip-based SPE-ICP-MS technique for continuous monitoring of trace elements in a simulated biological system was also demonstrated. To the best of our knowledge, this is the first paper to report the direct exploitation of a PMMA chip as an SPE adsorbent for online sample pretreatment and trace metal preconcentration prior to ICP-MS measurement.     

Direct determination of trace rare earth elements in ancient porcelain samples with slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

A method for the direct determination of trace rare earth elements in ancient porcelain samples by slurry sampling fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry was developed with the use of polytetrafluoroethylene as fluorinating reagent. It was found that Si, as a main matrix element in ancient porcelain sample, could be mostly removed at the ashing temperature of 1200 °C without considerable losses of the analytes. However, the chemical composition of ancient porcelain sample is very complicated, which makes the influences resulting from other matrix elements not be ignored. Therefore, the matrix effect of ancient porcelain sample was also investigated, and it was found that the matrix effect is obvious when the matrix concentration was larger than 0.8 g l^− 1. The study results of particle size effect indicated that when the sample particle size was less than 0.057 mm, the particle size effect is negligible. Under the optimized operation conditions, the detection limits for rare earth elements by fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry were 0.7 ng g^− 1 (Eu)–33.3 ng g^− 1(Nd) with the precisions of 4.1% (Yb)–10% (La) (c = 1 μg l^− 1, n = 9). The proposed method was used to directly determine the trace rare earth elements in ancient porcelain samples produced in different dynasty (Sui, Ming and Qing), and the analytical results are satisfactory.     

Evaluation of the analytical performance of inductively coupled plasma mass spectrometry for the simultaneous determination of major and minor elements in basic slags

The application of inductively coupled plasma mass spectrometry to the analysis of basic slags has been studied. A conventional dissolution-fusion procedure and a microwave digestion system were used for sample dissolution. Suitable selection of the analyte isotopes and the use of appropriate instrument settings and of internal standardization makes it possible to determine the major and minor elements in the same test sample dilution. Use of the omnirange device and low-abundance isotopes for the determination of the major elements is evaluated. The influence of the attack reagents is tested and the interferences caused by polyatomic ions are studied and corrected by applying elementary mathematical equations. For the major and minor elements considered, precision was found to be better than 1% (RSD). Results are presented for three basic slag reference materials and the agreement between the certified and found values shows the capacity of the method accurately to determine elemental concentrations in basic slags.     

High-throughput determination of seven trace elements in food samples by inductively coupled plasma-mass spectrometry

A method was developed for high-throughput determinations of 7 elements in food samples, namely antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and tin (Sn). The samples were digested by closed-vessel microwave-assisted digestion using concentrated nitric acid (HNO3) as the medium, followed by microwave- assisted evaporation to concentrate the sample solutions before dilution to the desired volume. The microwave-assisted evaporation procedure effectively reduced the final acid concentration to around 8% before analysis by inductively coupled plasma-mass spectrometry (ICP-MS). This reduction allows determination by ICP-MS to proceed without further sample dilution, which would affect the detection limit. The method was validated, and method recoveries for As, Cd, Cr, Pb, and Hg were within the certified ranges of the chosen certified reference materials. Recoveries of the 7 elements from spiked samples ranged from 93.1 to 103.6%. The standard uncertainties of precision for the 7 elements were between 3.1 and 4.3%. Interlaboratory comparison studies for As, Cd, and Pb gave z-scores ranging from -0.2 to 0.3.     

Determination of trace elements in residual oil by high-resolution inductively coupled plasma mass spectrometry

An analytical method using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of 20 elements, including Na, Mg, Al, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, and Pb elements, in residual oil was described. The sample was dissolved in HNO₃ by microwave digestion, and then the above 20 elements in the solution were analyzed directly by HR-ICP-MS. Most of the spectral interferences could be avoided by measuring in the high-resolution mode. The matrix effect caused by the sample-digesting solution and corrected by Sc, Rh, and Bi as the internal standard elements was studied in detail. The optimum condition of the determination was also tested and discussed. The result showed that the detection limits of the method were in the range of 0.014 to 11.6 μg L⁻¹; the relative standard deviation was less than 3.8% and recoveries in the samples were in the range of 88.4% to 108.0%. This method can be used to determine the trace elements in residual oil with the features of accurate, rapid, and convenient determination.     

电感耦合等离子体质谱法测定高纯金中铝、砷、铋、铬、铁、铅、锑、硒、碲、铱痕量元素

建立了微波消解-内标法-标准加入-ICP-MS法测定高纯黄金中铝、砷、铋、铬、铁、铅、锑、硒、碲、铱等痕量元素的分析方法.从试样溶解方式、内标元素及同位素的选择、仪器检测模式的优化及降低基体抑制效应等方面进行优化.实验加标回收率为99.5％ ～110％,相对标准偏差(RSD)为0.050％ ～6.5％.实验的准确度和精...     

Application of laser ablation inductively coupled mass spectrometry (LA-ICP-MS) for the determination of major, minor, and trace elements in bark samples

The large surface area of barks from many tree species enables the effective accumulation of pollutants. Therefore, the analysis of bark material will provide useful information about the degree of pollution of a certain region. The determination of main, minor, and trace elements (Al, Ca, Cd, Ce, Cr, Cu, Fe, Mn, P, Pb, S, Ti and Zn) in bark was performed with an Nd:YAG laser coupled to an ICP-MS system. Bark standards for the calibration by laser ablation ICP-MS were prepared from different bark layers which differ for some relevant elements in concentrations. Four digestion procedures for the decomposition of the standard pellets, the numbers of laser shots per sample and of samples per region necessary have been investigated. Representative results were obtained for 5 or more samples taken from different individuals of one species of a sampling area and the averaged element concentrations of 10 separately placed laser shots for each sample. Laser ablation ICP-MS was applied for the characterization of real bark samples from different regions with high and low pollution burden. It was shown that the method is well suited to characterize different degrees of environmental impact. Anthropogenic sources were responsible for the higher concentrations of most of the elements under investigation. Received: 26 April 1999 / Revised: 24 August 1999 / /Accepted: 28 August 1999