Determination of Cesium,Thorium and Uranium in IAEA Standard Reference Materials by ICP-MS

The collaborative analysis of the selected biological reference materials for use in Coordinated Research Programme. A method has been presented for determination of Reference Values of Cs,Th and U in 6 Kinds of SRM including NIST-SRM 1548 and 1548a Total Diet,SRM 1486 Bone Meal,SRM 8414 Bovine Muscle Powder,SRM 1575 Pine Needles and SRM 1566a Oyster Tissue provided by IAEA useing Elan 5000 ICP-MS (P-E/SCIEX).     

The ICP-MS approach to environmental studies

The certification of marine materials for trace metals is a process which challenges every technique involved, especially if a technique is as recent as inductively coupled plasma mass spectrometry (ICP-MS), Developmental work was required for several materials (natural waters, biological materials, marine sediments). It is reviewed here, in an attempt to show how one can take full advantage of ICP-MS. This includes a review of the digestion procedures developed for the multielement analysis of biological materials and marine sediments in order to minimize spectroscopic interferences. The multielement analysis of natural waters is also reviewed, in particular that of saline waters which requires a separation of the analytes from the alkali and alkaline earths elements and a preconcentration of the analytes on a column of silicaimmobilized 8-hydroxyquinoline. The potential of performing this separation/preconcentration procedure on-line is showed using both published and original results. Finally, the application of ICP-MS to speciation is illustrated by the determination of methylmercury in biological materials after extraction, and by the determination of arsenic species by high performance liquid chromatography coupled to ICP-MS.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, AustriaThe work described was carried out while the author was a Research Associate at the Analytical Chemistry Section, Chemistry Division, National Research Council of Canada, Ottawa, K1A OR9, Canada     

Optode for uranium(VI) determination in aqueous medium

A quantification procedure of trace elements during colloid size fractionation was developed and validated. This procedure is based on the hyphenation between Asymmetrical Flow Field-Flow Fractionation (As-Fl-FFF) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The optimisation of the procedure was performed on a soil leachate spiked with six trace elements selected for their environmental and health impact (As, Cd, Sb, Se, Sn and Pb). The elements in the spiked sample were on-line monitored during the fractionation. The validation was carried out by comparison with a second off-line quantification procedure based on fraction collection and total element analysis by ICP-MS. This off-line one was previously validated using reference materials. Finally, the analytical performances of the two procedures were compared.     

Determination of rare earth elements in Indian kimberlite using inductively coupled plasma mass spectrometer (ICP-MS)

A method has been developed for the analysis of rare earth elements (REEs) in kimberlite samples using inductively coupled plasma mass spectrometer (ICP-MS). The samples were dissolved using sodium peroxide fusion and after appropriate dilutions the solutions were analyzed using ICP-MS. The paper presents the concentration of rare-earth elements as determined by ICP-MS in eight kimberlite samples from Central India. The method was validated using certified reference materials STSD-1 and STSD-2 from Canadian Certified Reference Material Project. The method detection limit of various REEs varies from 0.12 to 1.54?mg?kg^?1. The total REE concentrations range from 418 to 726?mg?kg^?1 and fall within the interval of those reported in the literature for kimberlites. Despite the marked difference in the REE contents, all the analyzed samples show similar REE patterns that resemble those for kimberlites. In order to compare ICP-MS results, the samples were analyzed using instrumental neutron activation analysis which is a reference method for determination of REEs in geological samples.     

Analysis of leaves by using the laser ICP-MS with isotope dissolution method

The use of laser ablation inductively coupled mass spectrometry (laser ICP-MS), in combination with a calibration procedure involving the addition of enriched isotopes, for the determination of trace elements in birch leaves and their ashes is described. Samples are pressed into pellets without binder materials and analyzed using the ICP-MS spectrometer ELAN 5000 with the laser sampler type 320 (Perkin Elmer). The analytical results obtained by two methods are compared with the values obtained after digestion of the same samples and analysis of the resulting solutions by ICP-MS. The results are discussed in terms of precision, accuracy and limits of detections.     

Analysis of leaves by using the laser ICP-MS with isotope dissolution method

The use of laser ablation inductively coupled mass spectrometry (laser ICP-MS), in combination with a calibration procedure involving the addition of enriched isotopes, for the determination of trace elements in birch leaves and their ashes is described. Samples are pressed into pellets without binder materials and analyzed using the ICP-MS spectrometer ELAN 5000 with the laser sampler type 320 (Perkin Elmer). The analytical results obtained by two methods are compared with the values obtained after digestion of the same samples and analysis of the resulting solutions by ICP-MS. The results are discussed in terms of precision, accuracy and limits of detections.     

Inorganic trace analysis by mass spectrometry

Mass spectrometric methods for the trace analysis of inorganic materials with their ability to provide a very sensitive multielemental analysis have been established for the determination of trace and ultratrace elements in high-purity materials (metals, semiconductors and insulators), in different technical samples (e.g. alloys, pure chemicals, ceramics, thin films, ion-implanted semiconductors), in environmental samples (waters, soils, biological and medical materials) and geological samples. Whereas such techniques as spark source mass spectrometry (SSMS), laser ionization mass spectrometry (LIMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS) and inductively coupled plasma mass spectrometry (ICP-MS) have multielemental capability, other methods such as thermal ionization mass spectrometry (TIMS), accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS) have been used for sensitive mono- or oligoelemental ultratrace analysis (and precise determination of isotopic ratios) in solid samples. The limits of detection for chemical elements using these mass spectrometric techniques are in the low ng g⁻¹ concentration range. The quantification of the analytical results of mass spectrometric methods is sometimes difficult due to a lack of matrix-fitted multielement standard reference materials (SRMs) for many solid samples. Therefore, owing to the simple quantification procedure of the aqueous solution, inductively coupled plasma mass spectrometry (ICP-MS) is being increasingly used for the characterization of solid samples after sample dissolution. ICP-MS is often combined with special sample introduction equipment (e.g. flow injection, hydride generation, high performance liquid chromatography (HPLC) or electrothermal vaporization) or an off-line matrix separation and enrichment of trace impurities (especially for characterization of high-purity materials and environmental samples) is used in order to improve the detection limits of trace elements. Furthermore, the determination of chemical elements in the trace and ultratrace concentration range is often difficult and can be disturbed through mass interferences of analyte ions by molecular ions at the same nominal mass. By applying double-focusing sector field mass spectrometry at the required mass resolution—by the mass spectrometric separation of molecular ions from the analyte ions—it is often possible to overcome these interference problems. Commercial instrumental equipment, the capability (detection limits, accuracy, precision) and the analytical application fields of mass spectrometric methods for the determination of trace and ultratrace elements and for surface analysis are discussed.     

Comparison of NAA and ICP-MS for the determination of major and trace elements in environmental sample

Summary Major and trace elements in soil and plant samples, including standard reference materials were determined by means of neutron activation analysis (NAA) and inductively coupled plasma-mass spectrometry (ICP-MS). The analytical procedure for NAA utilized dried powder samples. The concentration of iodine in soil samples was determined by radiochemical NAA. The irradiated samples were cooled and then counted with a Ge gamma-ray detector connected to a multi-channel analyzer. For ICP-MS analysis, the samples were decomposed by microwave digestion with an acid mixture. The concentration of I in the soil samples was measured by ICP-MS after separation by ignition. The analytical values for most elements in the environmental samples by both methods were in good agreement, whereas sample treatments were different. Measured value of Zr in the soil samples by ICP-MS was about 50% lower than that by NAA. It should be assumed that some minerals of Zr in soil particles were not entirely dissolved by the acid mixture. Analytical results of Cd for three different Cd levels in unpolished rice flour samples (NIES 10-a, b and c) determined by ICP-MS were in agreement with certified values. The concentration of Cd in the sample with the lowest Cd level, as determined by NAA with 57% counting error, was 3 times higher than the certified value.     

Development of a procedure for the multi-element determination of trace elements in wine by ICP-MS

An inductively coupled plasma mass spectrometric (ICP-MS) procedure has been developed for the determination of trace elements in wine. The procedure consists in simple 1+1 dilution of the wine and semi-quantitative analysis (without external calibration) using In as internal standard. Thirty-one elements at concentrations ranging from 0.1 mg mL(-1) to 0.5 ng mL(-1) can be determined by ICP-MS analysis with and without digestion. It was investigated whether a matrix effect observed for EtOH in the wine matrix can be overcome by application of a micro-concentric nebulizer with a membrane desolvator (MCN 6000). The results obtained for the MCN 6000 are compared with those obtained by use of a conventional Meinhard nebulizer. It is shown that the observed matrix effect can only be compensated by use of an internal standard for the Meinhard nebulizer, but not for the MCN 6000. Results for ICP-MS are compared with those obtained by total reflection X-ray fluorescence spectrometry (TXRF).     

Applications of inductively coupled plasma mass spectrometry and laser ablation inductively coupled plasma mass spectrometry in materials science

Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) have been applied as the most important inorganic mass spectrometric techniques having multielemental capability for the characterization of solid samples in materials science. ICP-MS is used for the sensitive determination of trace and ultratrace elements in digested solutions of solid samples or of process chemicals (ultrapure water, acids and organic solutions) for the semiconductor industry with detection limits down to sub-picogram per liter levels. Whereas ICP-MS on solid samples (e.g. high-purity ceramics) sometimes requires time-consuming sample preparation for its application in materials science, and the risk of contamination is a serious drawback, a fast, direct determination of trace elements in solid materials without any sample preparation by LA-ICP-MS is possible. The detection limits for the direct analysis of solid samples by LA-ICP-MS have been determined for many elements down to the nanogram per gram range. A deterioration of detection limits was observed for elements where interferences with polyatomic ions occur. The inherent interference problem can often be solved by applying a double-focusing sector field mass spectrometer at higher mass resolution or by collision-induced reactions of polyatomic ions with a collision gas using an ICP-MS fitted with collision cell. The main problem of LA-ICP-MS is quantification if no suitable standard reference materials with a similar matrix composition are available. The calibration problem in LA-ICP-MS can be solved using on-line solution-based calibration, and different procedures, such as external calibration and standard addition, have been discussed with respect to their application in materials science. The application of isotope dilution in solution-based calibration for trace metal determination in small amounts of noble metals has been developed as a new calibration strategy. This review discusses new analytical developments and possible applications of ICP-MS and LA-ICP-MS for the quantitative determination of trace elements and in surface analysis for materials science.     

Determination of uranium and selected elements in Polish dictyonema shales and sandstones by ICP-MS

Inductively coupled plasma mass spectrometry was used for characterization of Polish dictyonema shales and sandstones as a potential source of uranium and other technologically important elements. Influence of sample digestion of these materials for the determinations: U, Th, Cu, Co, Mn, Zn, La, V, Yb, Mo, Ni, Sb and Fe has been tested. The method involved two-step microwave acid digestion, followed by direct determination by ICP-MS. The instrument used for all determinations was ELAN DRC II (Perkin Elmer) with crossflow nebulizer with Scott double-pass spray chamber and Ni cones. Certified Reference Materials were used as a quality control standard to validate the applied analytical procedure. The expanded measurement uncertainty U (k = 2) ranged from 5 to 15 %, in dependence on the element. The obtained results provided information on the contents of minor and trace elements in shales and sandstones depending on their origin. At this moment, these geological deposits can be treated as a potential source of raw elements.     

Simultaneous determination of inorganic mercury,methylmercury, and total mercury concentrations in cryogenic fresh-frozen and freeze-dried biological reference materials

Two speciated isotope dilution (SID) approaches consisting of a single-spike (SS) method and a double-spike (DS) method including a reaction/transformation model for the correction of inadvertent transformations affecting mercury species were compared in terms of accuracy, method performance, and robustness for the simultaneous determination of methylmercury (MeHg), inorganic mercury (iHg), and total mercury (HgT) concentrations in five biological Standard Reference Materials (SRMs). The SRMs consisted of oyster and mussel tissue materials displaying different mercury species concentration levels and different textural/matrix properties including freeze-dried (FD) materials (SRMs 1566b, 2976, and 2977) and cryogenically prepared and stored fresh-frozen (FF) materials (SRMs 1974a, 1974b). Each sample was spiked with (201)iHg (Oak Ridge National Laboratory, ORNL) and Me(202)Hg (Institute for Reference Materials and Measurements. IRMM-670) solutions and analyzed using alkaline microwave digestion, ethylation, and gas chromatography inductively coupled plasma mass spectrometry (GC/ICP-MS). The results obtained by the SS-SID method suggested that FF and FD materials are not always commutable for the simultaneous determination of iHg, MeHg, and HgT, due to potential transformation reactions resulting probably from the methodology and/or from the textural/matrix properties of the materials. These transformations can occasionally significantly affect mercury species concentration results obtained by SS-SID, depending on the species investigated and the materials considered. The results obtained by the DS-SID method indicated that the two classes of materials were commutable. The simultaneous and corrected concentrations of iHg, MeHg, and HgT obtained by this technique were not found to be statistically different form the certified and reference concentration together with their expanded uncertainty budgets for the five SRMs investigated, exemplifying the robustness, the accuracy, and the improved commutability of this method compared to SS-SID measurements.     

Determination of metals in composite diet samples by inductively coupled plasma-mass spectrometry

A study was conducted to evaluate the applicability of inductively coupled plasma-mass spectrometry (ICP-MS) techniques for determination of metals in composite diets. Aluminum, cadmium, chromium, copper, lead, manganese, nickel, vanadium, and zinc were determined by this method. Atmospheric pressure microwave digestion was used to solubilize analytes in homogenized composite diet samples, and this procedure was followed by ICP-MS analysis. Recovery of certified elements from standard reference materials ranged from 92 to 119% with relative standard deviations (RSDs) of 0.4-1.9%. Recovery of elements from fortified composite diet samples ranged from 75 to 129% with RSDs of 0-11.3%. Limits of detection ranged from 1 to 1700 ng/g; high values were due to significant amounts of certain elements naturally present in composite diets. Results of this study demonstrate that low-resolution quadrupole-based ICP-MS provides precise and accurate measurements of the elements tested in composite diet samples.     

Dry ashing of organic rich matrices with palladium for the determination of arsenic using inductively coupled plasma-mass spectrometry

A dry ashing procedure is developed for the determination of As in organic rich matrices such as wheat flour, lichen and tobacco leaves. The volatility of As during dry ashing is avoided by the addition of palladium nitrate [Pd(NO₃)₂]. The recovery of both As(III) and As(V) is found to be near quantitative. The residue after dry ashing is dissolved in nitric acid (HNO₃) and analysed by inductively coupled plasma-mass spectrometry (ICP-MS). The process blank and limit of detection (LOD) are 11 and 6.6 ng g⁻¹, respectively. The procedure is applied for the determination of As in certified reference materials namely wheat flour NIST SRM 1567a (National Institute of Standards and Technology Standard Reference Material), lichen BCR CRM 482 (Institute for Reference Materials, European Commission) and Virginia tobacco leaves CTA-VTL-2 (Poland Academy of Sciences). The results obtained by the present procedure are in good agreement with the certified values and also determined after complete dissolution of samples using closed microwave digestion.     

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.     

Possibilities of the elemental analysis of dry biological material by fast neutron activation analysis

The applicability of a 400 kV neutron generator in the elemental analysis of dry biological material is considered. Data for the specific count-rates of 66 elements are given. A procedure for the determination of N, Mg, Si, P, K and Ca is described. The results for three Standard Reference Materials and some samples are given.     

Sequential extraction of U, Th, Ce, La and some heavy metals in sediments from Ortigas river, Spain

The extractable contents of U, Th, Ce, La, Cu, Cr, Ni and Zn in two sediment samples collected from the Ortigas river have been analysed using the three step sequential extraction procedure (SEP) described by BCR, Community Bureau of Reference (now Standards Measurements and Testing Programme) of the European Union. In order to perform a mass balance, a fourth step has been included, i.e. digestion of the residue from the third extraction step. ICP-AES was used for the determination of Cu, Cr, Ni, Zn, Th, Ce and La. Because of the inadequate sensitivity of ICP-AES for the analysis of uranium, ICP-MS was used for the determination of this element. Standard addition method was required, because of the matrix effects. Finally, SEP was applied to the Ortigas river sediments, showing that most of the elements were found mainly associated with the residual sediment fraction, except for uranium, which was found as an exchangeable species in approximately 60% of its total content. Recoveries of 86-108% have been obtained.     

Determination of calcium, iron and manganese in moss by automated discrete sampling flame atomic absorption spectrometry as an alternative to the ICP-MS analysis

An automated, fast and reliable procedure has been developed for flame atomic absorption analysis of Ca, Fe and Mn in moss. The method is suitable for routine analysis of a large number of moss samples and allows sequential determination of all three elements in the same solution. In order to inhibit the matrix interference on Ca and to level the diverse analytical behaviour of the moss matrix, approximately 1% La was added to both samples and standard solutions as well. An integrated system of ‘sandwich-type’ air segmented discrete sample introduction and flame atomic absorption detection (ASDI-FAAS) was successfully applied. It works at ‘solvent-air-sample-air-solvent’ mode, which tolerates the introduction of high salt content solutions, reduces reagent and sample consumption and allows the application of data treatment models to pseudo-steady state signals for bettering the repeatability. For moss samples containing high Ca and Fe concentrations, equivalent procedure was used by turned on 45° burner head without worsening the analytical characteristics. Concerning these three elements, the method is suggested as a cheaper, easier and more trustworthy alternative with a better precision to the inductively coupled plasma-mass spectrometry (ICP-MS) one. The ASDI-FAAS results were used for selection of appropriate isotopes and correction procedures for ICP-MS determination. Both methods show good agreement of the Ca, Fe and Mn results that correspond to the moss reference materials tested.     

Detection and identification of bacteria using direct injection inductively coupled plasma mass spectroscopy

In this study, an inductively coupled plasma mass spectrometer (ICP-MS) was used for the inorganic chemical characterization of biological materials by direct injection. ICP-MS has the advantage of sub-nanogram/gram detection limits for most elements making it a sensitive tool for the detection and characterization of aerosolized biological material. Suspended, microgram-sized samples of Bacillus subtilis spores (BG), Bacillus subtilis vegetative cells (Bg), and Bacillus thuringiensis (Bt) were analyzed via direct injection and they exhibit unique chemical signatures reflecting the processing history of each organism.     

The utilization of modified BCR three-step sequential extraction procedure for the fractionation of Cd, Cr, Cu, Ni, Pb and Zn in soil reference materials of different origins

A modified three-step sequential extraction procedure for the fractionation of heavy metals, proposed by the Commission of the European Communities Bureau of Reference (BCR) has been applied to the Slovak reference materials of soils (soil orthic luvisols, soil rendzina and soil eutric cambisol), which represent pedologically different types of soils in Slovakia. Analyses were carried out by flame or electrothermal atomic absorption spectrometry (FAAS or ETAAS). The fractions extracted were: exchangeable (extraction step 1), reducible-iron/manganese oxides (extraction step 2), oxidizable-organic matter and sulfides (extraction step 3). The sum of the element contents in the three fractions plus aqua-regia extractable content of the residue was compared to the aqua-regia extractable content of the elements in the origin soils. The accuracy obtained by comparing the determined contents of the elements with certified values, using BCR CRM 701, certified for the extractable contents (mass fractions) of Cd, Cr, Cu, Ni, Pb and Zn in sediment following a modified BCR-three step sequential extraction procedure, was found to be satisfactory.