Determination of lithium in biological samples by inductively coupled plasma mass spectrometry

Lithium was determined in human serum by inductively coupled plasma mass spectrometry. Sample preparation was kept to the minimum: serum samples were diluted and beryllium was added as internal standard. Special attention was given to the choice of the internal standard and to the occurrence of memory effects. To test the accuracy of the method several biological reference materials were analysed, namely a “Second-Generation” Biological Reference Material (Freeze-Dried Human Serum) (University of Ghent), Human Serum SRM 909, Whole Egg Powder SRM 1845 and Mixed Human Diet SRM 1548 (National Institute of Standards and Technology). The results were compared with those obtained by other techniques. For the “second-generation” reference freeze-dried human serum a mean lithium concentration of 15.10 ng g^?1 with a standard deviation of 0.54 ng g^?1 dry weight was found. Analyses on serum samples from healthy individuals yielded lithium concentrations ranging from 0.22 to 0.97 μg l^?1.     

Sensitive determination of traces of boron in waters,fertilizers na geological and biological materials by isotope-dilution mass spectrometry

A method is described for determining traces of boron in water, fertilizers, geological and biological (reference) materials by isotope-dilution mass spectrometry after separation on an Amberlite IRA-743 borate-selective ion-exchange column. Boron (–250 ng g^?1) in water can be determined with an accuracy of 5–20% (computed on a 2s basis). After correction for weighing errors and for moisture, content, which varied from 0 to 8% for the samples tested, 1–35 μg g^?1 boron in “dry” fertilizer, biological or geological sample can be assayed with an accuracy of 5–30% (2s). In an IAEA interlaboratory program on a simulated fresh water, the method yielded a value of 24.3 +? 2 μg l^?1, compared to the make-up value of 25 μg l^?1.     

Assessment of differential-pulse adsorption voltammetry for the simultaneous determination of nickel and cobalt in biological materials

An assessment of the voltammetric method based on chelate adsorption at the hanging mercury drop electrode is described for the simultaneous determination of nickel and cobalt in biological materials. The interfacial accumulation of the elements as metal dimethylglyoximates during the adsorption step, and the use of differential-pulse voltammetry during the reduction step, provide substantial gains in the sensitivity of their voltammetric responses. The decomposition of the sample material by direct dry ashing provides a blank-free approach for the accurate determination of the elements. Application of the method to the available certified biological reference materials for cobalt and nickel was successful. The limits of detection obtained under the conditions of this study were 0.01 μg g^?1 and 0.02 μg g^?1 for cobalt and nickel, respectively, in bovine liver.     

Application of neutron activation analysis for trace element determinations in biological materials

Over the past three decades, more and more interest has been focused on trace eleemnts in biological materials. This increasing interest has gone hand in hand with the continuous improvement of analytical techniques. Neutron activation analysis has proven to be a most suitable method for the quantitative determination of a wide variety of trace (0.01–100 μg g^?1) and ultratrace (<0.01 μg g^?1) elements in biological materials. This technique has even played a preponderant role in this field.     

Three new mussel tissue standard reference materials (SRMs) for the determination of organic contaminants

Three new mussel tissue standard reference materials (SRMs) have been developed by the National Institute of Standards and Technology (NIST) for the determination of the concentrations of organic contaminants. The most recently prepared material, SRM 1974b, is a fresh frozen tissue homogenate prepared from mussels (Mytilus edulis) collected in Boston Harbor, Massachusetts. The other two materials, SRMs 2977 and 2978, are freeze-dried tissue homogenates prepared from mussels collected in Guanabara Bay, Brazil and Raritan Bay, New Jersey, respectively. All three new mussel tissue SRMs complement the current suite of marine natural-matrix SRMs available from NIST that are characterized for a wide range of contaminants (organic and inorganic). SRM 1974b has been developed to replace its predecessor SRM 1974a, Organics in Mussel Tissue, for which the supply is depleted. Similarly, SRMs 2977 and 2978 were developed to replace a previously available (supply depleted) freeze-dried version of SRM 1974a, SRM 2974, Organics in Freeze-Dried Mussel Tissue. SRM 1974b is the third in a series of fresh frozen mussel tissue homogenate SRMs prepared from mussels collected in Boston Harbor starting in 1988. SRM 1974b has certified concentration values for 22 polycyclic aromatic hydrocarbons (PAHs), 31 polychlorinated biphenyl congeners (PCBs), and 7 chlorinated pesticides. Reference values are provided for additional constituents: 16 PAHs, 8 PCBs plus total PCBs, 6 pesticides, total extractable organics, methylmercury, and 11 trace elements. PAH concentrations range from about 2 ng g^–1 dry mass (cyclopenta[cd]pyrene) to 180 ng g^–1 dry mass (pyrene). PCB concentrations range from about 2 ng g^–1 dry mass (PCB 157) to 120 ng g^–1 dry mass (PCB 153). The reference value for total PCBs in SRM 1974b is (2020 ± 420) ng g^–1 dry mass. Pesticide concentrations range from about 4 ng g^–1 dry mass (4,4-DDT) to 40 ng g^–1 dry mass (4,4-DDE). SRM 2977 has certified values for 14 PAHs, 25 PCB congeners, 7 pesticides, 6 trace elements, and methylmercury. Reference values for 16 additional PAHs and 9 inorganic constituents are provided, and information values are given for 23 additional trace elements. SRM 2978 has certified and reference concentrations for 41 and 22 organic compounds, respectively, and contains contaminant levels similar to those of SRM 1974b. Organic contaminant levels in SRM 2977 (mussels from Guanabara Bay, Brazil) are typically a factor of 2 to 4 lower than those in SRM 1974b and SRM 2978. The organic contaminant concentrations in each new mussel tissue SRM are presented and compared in this paper. In addition, a chronological review of contaminant concentrations associated with mussels collected in Boston Harbor is discussed as well as a stability assessment of SRM 1974a.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

The determination of strontium in human blood serum and packed blood cells by radiochemical neutron activation analysis

Strontium is a trace element whose distribution and metabolism are similar to those of calcium, its close chemical analogue. The element received scientific attention because of its potential beneficial effects in the treatment of osteoporosis andosteolytic metastatic bone lesions but also because of the possible problems associated with the retention of⁹⁰Sr from radioactive fall-out. In continuation of a series of experiments intended to establish reliable reference values for trace elements in human blood serum and packed blood cells, we set up a project to determine also strontium. The following values were obtained (mean±standard deviation): 22.2±4.8 ng/ml (serum) and 2.85±1.11 ng/g wet weight (packed blood cells).     

Verbundverfahren zur Multielement-Spurenbestimmung in hochreinem Chrom nach Spuren—Matrix-Trennung

(Simultaneous determination of trace elements in high-purity chromium by inductively-coupled plasma/atomic emission spectrometry after matrix separation.) The production of high-purity metals requires routine determinations of elements in the ng g^?1 range. Procedures based on wet chemical separation of matrix and trace elements followed by inductively-coupled plasma/atomic emission spectrometry are suitable. The separation of 19 trace metals (Be, Bi, Ca, Cd, Co, Cu, Fe, La, Mg, Mn, Nb, Ni, Pb, Ta, Ti, Th, U, Zn and Zr) from high-purity chromium powder is described. The powder is dissolved in hydrochloric acid and oxidized with perchloric acid or alkaline hydrogen peroxide, and the trace elements are precipitated at pH 11–13 and collected on cellulose loaded with indium hydroxide or on cellulose-Hyphan. The detection limits of the total procedure vary from 10 ng g^?1 for cadmium to 600 ng g^?1 for zinc.     

Analysis of inorganic materials by beam techniques — the challenge of high technology

For property-related characterization of inorganic materials, information is needed about bulk composition, distribution of elements, compounds, phases and structural features. Photons, electrons, charged ions or neutrons, often used as focused beams provide access to this information. The major trends in this field are the development or improvement of methods to obtain new information or to increase spatial resolution, detection power, precision and accuracy of analysis. The present state of the analysis of inorganic materials by using beam techniques is discussed in a selective manner. Emphasis is placed on the following problems, which are important for basic research and for development of high-technology materials: ultratrace bulk analysis in the pg g^?1 to ng g^?1 range; analysis for phases, trace elements and isotopes, including structural characterization; and surface analysis, with emphasis on the characterization of trace elements at surfaces, quantitative distribution of trace elements in heterogeneous structures, and surface structural analysis with atomic resolution.     

Microwave dissolution for the determination of mercury in biological samples

Microwave dissolution in closed teflon vessels is described for the determination of ng g^?1 contents of mercury in biological materials, prior to two-stage gold amalgamation and cold-vapour atomic absorption spectrometry. Six samples can be decomposed simultaneously within 20 min, with a preset heating programme. The detection limit is 0.84 ng g^?1 for a 100-mg sample. Results for six certified reference materials agreed with the certified values.     

Determination of traces of As,Cd, Cr,Hg, Mn,Ni, Sb,Se, Sn and Pb in human hair by triple quadrupole ICP-MS

With the wide range of metallic contaminants discharged in the environment, studying the human health requires a growing number of elements to be monitored in biological samples. Hair analysis has been suggested as a suitable tool for biomonitoring environmental and occupational exposure to toxic elements. This study describes a method for the determination of 10 trace elements in hair samples using ICP-QQQ-MS. Combining the power of the MS/MS high-energy Helium mode with the MS/MS O₂ mass-shift mode, the method offers great analytical performances with detection limits reaching 0.0014 µg g^?1 for As, 0.0016 µg g^?1 for Cd, 0.012 µg g^?1 for Cr, 0.0035 µg g^?1 for Hg, 0.0055 µg g^?1 for Mn, 0.10 µg g^?1 for Ni, 0.0012 µg g^?1 for Sb, 0.0083 µg g^?1 for Sn, 0.011 µg g^?1 for Se and Pb. The accuracy of the method was tested on a human hair ERM® certified reference material. Percent recoveries varied from 91.3% and 106.9% being always in the acceptance range of 90–110%. For all analysed elements, RSD% of repeatability ranged between 0.6% and 9.0% and those of intermediate precision did not exceed the limit of 20% being always lower than 10% (except for As). The proposed method was applied for the determination of trace elements in hair samples from 20 unexposed subjects. The geometric mean levels were as follows: Cr 0.28 µg g^?1, Mn 0.30 µg g^?1, Sn 1.04µg g^?1, Sb 0.07 µg g^?1, Hg 0.42 µg g^?1, As 0.02 µg g^?1, Cd 0.03 µg g^?1, Ni 0.51 µg g^?1, Se 0.45 µg g^?1 and Pb 1.83 µg g^?1. Element concentrations were in the same range with the reported data. The reported results may be useful for environmental exposure assessment or comparisons studies when establishing reference values of trace elements in exposed population.     

Development of an accurate,sensitive, and robust isotope dilution laser ablation ICP-MS method for simultaneous multi-element analysis (chlorine,sulfur, and heavy metals) in coal samples

A method for the direct multi-element determination of Cl, S, Hg, Pb, Cd, U, Br, Cr, Cu, Fe, and Zn in powdered coal samples has been developed by applying inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with laser-assisted introduction into the plasma. A sector-field ICP-MS with a mass resolution of 4,000 and a high-ablation rate laser ablation system provided significantly better sensitivity, detection limits, and accuracy compared to a conventional laser ablation system coupled with a quadrupole ICP-MS. The sensitivity ranges from about 590 cps for ³⁵Cl⁺ to more than 6 × 10⁵ cps for ²³⁸U⁺ for 1 μg of trace element per gram of coal sample. Detection limits vary from 450 ng g⁻¹ for chlorine and 18 ng g⁻¹ for sulfur to 9.5 pg g⁻¹ for mercury and 0.3 pg g⁻¹ for uranium. Analyses of minor and trace elements in four certified reference materials (BCR-180 Gas Coal, BCR-331 Steam Coal, SRM 1632c Trace Elements in Coal, SRM 1635 Trace Elements in Coal) yielded good agreement of usually not more than 5% deviation from the certified values and precisions of less than 10% relative standard deviation for most elements. Higher relative standard deviations were found for particular elements such as Hg and Cd caused by inhomogeneities due to associations of these elements within micro-inclusions in coal which was demonstrated for Hg in SRM 1635, SRM 1632c, and another standard reference material (SRM 2682b, Sulfur and Mercury in Coal). The developed LA-ICP-IDMS method with its simple sample pretreatment opens the possibility for accurate, fast, and highly sensitive determinations of environmentally critical contaminants in coal as well as of trace impurities in similar sample materials like graphite powder and activated charcoal on a routine basis. Figure LA-ICP-IDMS allows direct multi-element determination in powdered coal samples     

Ultra-trace analysis of platinum in human tissue samples

Background levels of platinum were determined in human autopsy tissues taken from five individuals. The investigated specimens were lung, liver and kidney. Sample preparation involved microwave digestion followed by an open vessel treatment. Inductively-coupled plasma sector field mass spectrometry (ICP-SFMS) was applied in combination with an ultrasonic nebulization/membrane desolvation system for sample introduction. Isotope dilution analysis was employed for accurate quantification of platinum. Excellent procedural detection limits (3 s validation) of 20, 20 and 34 pg g^–1 dry weight were obtained for lung, liver and kidney tissue, respectively. Due to the lack of appropriate biological reference material, road dust (BCR-723) was used for method validation. Platinum levels ranging between 0.03 and 1.42 ng g^–1 were determined in the investigated samples. The platinum concentrations observed in human lung tissue may reflect the increasing atmospheric background levels of platinum originating from car catalysts. The presence of platinum in kidney and liver tissue samples clearly indicates the bioavailability of the element.     

Trace elements in sediments and bioaccumulation in European silver eels (Anguilla anguilla L.) from a Mediterranean lagoon (SE Italy)

Samples of surface sediments and tissues (liver and muscle) of commercially available European silver eels (Anguilla anguilla L.) collected from Varano lagoon (Italy) were analysed to determine trace element contents. Univariate and multivariate analyses were performed to highlight both the differences between sampling sites and the influence of channel discharges. Atomic ratios indices for sediment data and biological enrichment factors (BEF) for eel tissues were calculated in order to evaluate the enrichment factor due to human activities. The highest levels of As (11.9?µg?g^?1) and Zn (14.1?µg?g^?1) were observed in the south-eastern zone of the lagoon, which is influenced by urban and agricultural discharges. The low levels of Hg observed in this study (0.04?µg?g^?1) led us to exclude both natural and human local sources of this element. Trace element concentrations of all elements were lower in muscle than in liver tissue. Significant enrichment of Cu and Zn was found in livers.     

Determination of trace selenium in biological material by preconcentration and x-ray emission spectrometry

Selenium is determined in the ng g^?1 to μg g^?1 range in biological and environmental samples. A wet digestion procedure was optimized with respect to volatility losses and recovery yields, by using ⁷⁵Se metabolically incorporated into rat organs. Selenium is preconcentrated from the digestion liquid by a two-step reduction with 4 M HCl and ascorbic acid. The colloidal selenium formed is adsorbed on activated carbon and filtered on a Nucleopore membrane for measurement by energy-dispersive x-ray fluorescence. Almost complete recovery was obtained, and the detection limit was 20 ng, corresponding to 10 ng g^?1 for a 2-g sample. Biological reference materials were analyzed with satisfactory results, and the accuracy of the method was good.     

Preliminary homogeneity study of in-house reference material using neutron activation analysis and X-ray fluorescence

Summary Although many biological reference materials for quality control of trace element analysis are commercially available, there is still a need for additional local materials for special matrices. In the Latin American region a preliminary study has been commenced involving analytical strategies for the characterization of in-house reference material. A biological sample, prepared in Brazil, constitutes the first regional attempt to prepare reference material. It was analyzed by neutron activation analysis (NAA) and X-ray fluorescence (XRF) to verify its homogeneity. The determination of the trace elements and certain major elements was carried out by instrumental NAA. Trace elements such as Cd, Mn, Mo and Cu were determined using NAA with radiochemical separations to improve the sensitivity and precision. XRF was applied only to major constituents and some trace elements with concentration of more than 10 g/g. From a total of 18 elements analyzed, only Fe, Cr and Sc were not homogeneously distributed.     

Slurry Sampling Electrothermal Vaporization Combined with ICP-AES for Direct Analysis of Environmental Samples

In this article, a polytetrafluoroethylene (PTFE) slurry was used as a chemical modifier for direct determination of trace elements in environmental samples by electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) with slurry sampling. The vaporization behaviors of the analytes in slurry and solution were comparatively studied in the presence of PTFE. The main influence factors for this method were examined. Under the optimum operating conditions, the precision of this method was better than 7% with the detection limits varying from 1.7 ng mL^?1 (Cu) to 203 ng mL^?1 (Zn). The proposed method has been applied to the direct determination of the trace elements in camphor tree leaves and standard reference material (the combined sample of branch and leaf of shrub, GBW 07603) with satisfactory results.     

A novel approach to decomposition of foodstuffs for stripping voltammetric determination of lead,cadmium and copper

Samples (ca. 0.3 g) are digested in 10-ml quartz vessels and the same vessel is used for anodic stripping voltammetry. Thus possible contamination during handling and dilution of the decomposed sample solution are avoided. A special design of column placed over the vessel provides digestion under reflux conditions without leakage and a glass cap fitted to another condenser enables the residual mineral acids (especially sulfuric acid) to be boiled out under low pressure conditions. The usual PTFE holder for electrodes and gas tubes is modified to facilitated insertion of the 10-ml vessel underneath. The system was checked on NBS standard reference materials (wheat flour and rice flour) and tested for the determinaton of Cd, Pb and Cu in baby foods. The limits of detection obtained for 3-min decomposition times were 0.3 ng g^?1, 4 ng g^?1 and 8 ng g^?1 for cadmium, lead and copper, respectively. The levels of these elements in various commercial baby foods are given.     

Direct multielement determination of trace elements in boron carbide powders by direct current arc atomic emission spectrometry using a CCD spectrometer

The use of direct current arc atomic emission spectrometry (DC-arc-AES) with a CCD spectrometer for the direct determination of the trace impurities Al, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Si, Ti, and Zr in three well characterized boron carbide powders is described. The detection limits obtained by the procedure were found to be between 0.2 (Mg) and 25 (Na) ??g?g^?1 for the above elements. Three boron carbide powder samples with trace element concentrations between 0.9 (Cu) and 934 (Si) ??g?g^?1 for Al, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Si, Ti, and Zr ?? including the standard reference material ERM?-ED102 ?? were analyzed by DC-arc-AES. The relative standard deviations for 9 measurements when using 5.0?±?0.3?mg of the respective samples were found to vary from 6.2 to 27% for Al and Cu, respectively. The trace elements Al, Ca, Cr, Cu, Fe, Mn, Ni, Si, Ti and Zr could be determined in the standard reference material and their concentrations determined by DC-arc AES were found to be between 89 and 116% of the accepted values. Fe and Ti were determined by DC-arc AES in the three boron carbide samples as well as in Al₂O₃, BN, SiC, coal fly ash, graphite and obsidian rock. The correlation coefficients of the plots of the net intensities versus the accepted values over the concentration ranges from 18 to 1750 and from 6 to 8000???g?g^?1 are 0.999 and 0.990 for Fe and Ti, respectively.

Direct determination of platinum group elements and their distributions in geological and environmental samples at the ng g<Superscript>−1</Superscript> level using LA–ICP–IDMS

Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA–ICP–IDMS) was applied to the direct and simultaneous determination of the platinum group elements (PGEs) Pt, Pd, Ru, and Ir in geological and environmental samples. A special laser ablation system with high ablation rates was used, along with sector field ICP–MS. Special attention was paid to deriving the distributions of PGEs in the pulverized samples. IDMS could not be applied to the (mono-isotopic) Rh, but the similar ablation behavior of Ru and Rh allowed Rh to be simultaneously determined via relative sensitivity coefficients. The laser ablation process produces hardly any oxide ions (which usually cause interference in PGE analysis with liquid sample injection), so the ICP–MS can be run in its low mass resolution but high-sensitivity mode. The detection limits obtained for the geological samples were 0.16 ng g⁻¹, 0.14 ng g⁻¹, 0.08 ng g⁻¹, 0.01 ng g⁻¹ and 0.06 ng g⁻¹ for Ru, Rh, Pd, Ir and Pt, respectively. LA–ICP–IDMS was applied to different geological reference materials (TDB-1, WGB-1, UMT-1, WMG-1, SARM-7) and the road dust reference material BCR-723, which are only certified for some of the PGEs. Comparisons with certified values as well as with indicative values from the literature demonstrated the validity of the LA–ICP–IDMS method. The PGE concentrations in subsamples of the road dust reference material correspond to a normal distribution, whereas the distributions in the geological reference materials TDB-1, WGB-1, UMT-1, WMG-1, and SARM-7 are more complex. For example, in the case of Ru, a logarithmic normal distribution best fits the analyzed concentrations in TDB-1 subsamples, whereas a pronounced nugget effect was found for Pt in most geological samples.     

Optimization of the Sample Preparation Procedure for the Determination of Trace Elements in Auricularia auricula by Inductively Coupled Plasma-Optical Emission Spectrometry

This study aimed to develop a precise and accurate method of sample preparation of Auricularia auricula for inductively coupled plasma-optical emission spectrometry-based trace element determination and to compare concentrations of seven trace elements (Mg, Fe, Mn, Zn, Ni, Cr, Sr) in six A. auricula samples belonging to three varieties with two cultivation substrates. Five sample preparation procedures, microwave-assisted digestion, nitric acid digestion with hot plate heating, nitric acid and perchloric acid digestion with hot plate heating, nitric acid digestion with ash content, and aqua regia digestion with ash content, were compared. The performance of the procedures was determined based on the precision and accuracy of the results and the limits of detection of the elements. The best results, with limits of detection of 0.60–6.60?ng?·?mL^?1 and recoveries for spiked samples between 93.80 and 105.00%, were found using nitric acid digestion with ash content. Six A. auricula samples were analyzed using the proposed procedure. Among the tested elements, the concentration of Fe was highest in all six A. auricula samples up to a maximum concentration of 284.83?µg?·?g^?1. The concentrations of Mn, Cu, and Ni increased in mixed stands (basswood, birch, and mongolica) compared with pine sawdust cultivation.