Mikael D. Axelsson

Application of double focusing sector field ICP-MS for multielemental characterization of human hair and nails : Part II: A study of the inhabitants of northern Sweden

Double-focusing sector-field, inductively coupled plasma-mass spectrometry was used for the determination of 71 elements in scalp hair and fingernail samples from an urban population group living in the north-east of Sweden. Samples (n = 114 for hair and n = 96 for nails) were taken from subjects without known occupational exposure to metals. From these results, concentration ranges were calculated and compared with published intervals. Statistical analysis was used to elucidate differences according to sex, age and smoking habit. It was found that significant correlations exist between different elements in hair and nails, as well as between hair and nail concentrations for several elements. Strong positive correlation for Hg, Cd, Pb, Sb and Bi levels between these media confirms that both can be used for exposure assessment for these elements. Several examples on the use of distribution patterns for the rare-earth elements (REE) and of Pb isotope ratios for assessment of exposure are given.

Application of double focusing sector field ICP-MS for multielemental characterization of human hair and nails. Part I. Analytical methodology

The capabilities of double focusing sector field inductively coupled plasma mass spectrometry (ICP-SMS) for the determination of 71 elements in hair and nails were studied. A microwave-assisted digestion procedure with nitric acid and hydrogen peroxide as well as direct sampling of the nails by laser ablation (LA) have been tested. Examples of spectral interferences are given and different correction procedures are discussed. Method detection limits below ng g(-1) were obtained for 39 elements investigated by using high-purity reagents and by taking special care to prevent contamination during preparation. However, these detection limits were insufficient for detection of some platinum group elements in the majority of the samples. The accuracy of the analytical procedure was estimated by analysis of the GBW07601 certified reference material as well as by participation in an interlaboratory comparison program. The reproducibility was assessed from replicate analysis (including sample preparation) and was found to be, as average values for all elements, 9-10% R.S.D. and 18-19% R.S.D. for hair and nails, respectively. Contribution from exogenous deposition was evaluated by analyzing samples before and after washing, as well as by studying spatial element distribution along hair and nails. It was found that even after sample washing, many elements are enriched in the surface of the nail.

Application of double focusing sector field ICP-MS for multielemental characterization of human hair and nails. Part III. Direct analysis by laser ablation.

The capabilities of laser ablation double focusing sector field inductively coupled plasma mass spectrometry for the determination of 55 elements in nails and hair were studied. Quantification was performed by external calibration using in-house matrix-matched standards in tablet form following correction for variations in ablation efficiency by internal standardization using a matrix element (S). For nails, intra-individual long- and short-term chronological variations as well as depth distribution patterns were studied. For the majority of elements tested, significant enrichment was found in the surface of the nail. Element distributions along a hair strand were investigated with a spatial resolution of 2.5 mm.

Multielemental analysis of Mn–Fe nodules by ICP-MS : optimisation of analytical method

Two acid digestion procedures (microwave-assisted and room temperature) were developed for the quantitative analysis of ferromanganese nodules by inductively coupled plasma double focusing sector field mass spectrometry (ICP-SFMS). Different compositions of the acid mixture, dilution factors and corrections for spectral interferences were tested. A combination of nitric, hydrochloric and hydrofluoric acids is necessary for complete sample digestion, with lowest acid to sample ratios (v/m) of 15 and 1.5, respectively, for the last two acids. Sample dilution factors higher than 2 x 10(4) should be used in order to decrease matrix effects and provide robust long-term instrumental operation. In spite of high dilution, method detection limits in the sub-microg g(-1) range were obtained for 54 out of 71 elements tested, due to the high detection capability of ICP-SFMS, as well as the special care taken to ensure the purity of reagents, to clean the instrument sample introduction system and to minimise sample handling. Owing to the presence of unresolved (at the resolution available) spectral interferences, accurate determination of Au, Hg, Os, Pd, Re and Rh is impossible without matrix separation. The accuracy of the entire analytical method was tested by the analysis of two nodule reference materials. The results generated agreed to within +/-2% for about 10, within +/-10% for more than 40 and within +/-20% for about 50 of 53 elements for which certified, recommended or literature values are available. A precision better than 3%, expressed as the between-digestion relative standard deviation (n = 4), was obtained for the majority of elements, except in cases limited by low analyte concentrations.

Multielement analysis of coal by ICP techniques using solution nebulization and laser ablation.

The combination of inductively coupled plasma atomic emission spectrometry and high resolution inductively coupled plasma mass spectrometry for the determination of 70 elements in coal were studied. Four microwave-assisted digestion procedures with different dissolution mixtures (nitric and hydrofluoric acids, aqua regia and hydrogen peroxide), lithium metaborate fusion with and without previous sample ashing as well as direct sampling by laser ablation (LA) have been tested. Examples of spectral interferences are given and different correction procedures are discussed. Detection limits in the low ng g(-1) range were obtained for most of the elements investigated by using high-purity reagents and by taking special care to prevent sample contamination during preparation. The precision was assessed from replicate analysis (including sample preparation) of coal samples and was found to be, as average values far all elements, 4-5% RSD and 10-15% RSD for procedures including sample digestion and LA sampling, respectively. The accuracy of the overall analytical procedures was estimated by analysis of certified reference materials and of a coal sample obtained from the Interlab Trace round robin test. Among the dissolution mixtures tested, the combination of nitric and hydrofluoric acids with hydrogen peroxide provide the best agreement with certified, recommended, literature-compiled or consensus values, though fusion is necessary to obtain quantitative recoveries for Si, Cr, Hf, W, Zr, Y. In general, results obtained by LA fall within +/-20% of those obtained after digestion.

Analyte- and matrix-dependent elemental response variations in laser ablation inductively coupled plasma mass spectrometry : Part 1. The roles of plasma and ion sampling conditions

Elemental response variations as a function of carrier gas flow rate in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were studied for a wide range of analytes. The effect ...

Determination of major and trace elements in sphalerite using laser ablation double focusing sector field ICP-MS

Abstract The analytical performance of laser ablation (LA) for the determination of Co, Fe, Cd, Ag, Mn, Cu and S in sphalerite was evaluated using double focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS). Samples were collected from Zinkgruvan, situated in the south central Sweden. The use of Zn for internal standardisation, together with correction for FeS impurities in sphalerite, allows straightforward quantification without using external methods for the determination of the actual Zn content. LA–ICP-SFMS results were compared with data obtained by conventional pneumatic nebulisation introduction of sample solutions following acid digestion. Good agreement between the two methods was obtained for homogeneously distributed elements. For the majority of the elements under consideration, LA–ICP-SFMS precision was better than 10% RSD.

Adsorption of trace elements on pyrite surfaces in sulfidic mine tailings from Kristineberg (Sweden) a few years after remediation

Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has been used to determine the elemental composition of the surface and interior layers of pyrite grains from the mine tailings from Kristineberg (northern Sweden) in order to determine concentration gradients between these two layers. The pyrite grains were collected from oxidized and unoxidized zones within the tailings. The aim of this study was to assess the role of pyrite surfaces as sites for the attenuation of solutes from the mine-tailings porewater. The normalized intensities of Cu, Zn, Ag, Sb, Ce, Pb and Bi are highest at the surface of each grain (within the surface layer drilled by the LA) and decrease towards the interior. The surface adsorption of Cu, Zn and Pb is more pronounced within the unoxidized than within the oxidized zone of the tailings. Copper exhibits a distinct concentration peak at the surface of the pyrite grains below the pre-remediation oxidation front. Silver, Sb, Bi, As and Au are preferably adsorbed within the uppermost layer of the oxidized zone in the tailings, where the pH is as high as 6.2. The conversion of intensity signals of the elements to concentration values in ppm was accomplished using an external calibration against an in-house pyrite standard.

Trace elements in magnetite from Kiruna, northern Sweden, as determined by LA-ICP-MS

Abstract Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has been used to determine the concentrations of 17 trace elements (V, Mn, Cu, Zn, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Ce, Tl, Pb, B, Th, and U) in magnetite from the Kiirunavaara iron deposit in northern Sweden. Magnetite grains were sampled from four different parts of the concentrating plant. An attempt was made to investigate if there are any concentration differences between the surface layer and interior layers in magnetite grains, using a two-stage soft ablation procedure. Possible non-representative sampling due to fractionation, was evaluated by using a polished in-house calibration standard. The two-stage ablation showed no significant differences between the first and second layer, in terms of elemental compositions. Concentrations of V (up to 2300 μg/g) and Mn (up to 7850 μg/g) are the most abundant trace elements encountered. Cu, Zn, and Pb are among the less common trace elements in magnetite. The conversion of intensity signals of the elements to concentration values mg/g was achieved by using a polished in-house magnetite standard and Fe for internal standardization.

High spatial resolution analysis of ferromanganese concretions by LA-ICP-MS

A procedure was developed for the determination of element distributions in cross-sections of ferromanganese concretions using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The effects of carrier flow rates, rf forward power, ablation energy, ablation spot size, repetition rate and number of shots per point on analyte intensity were studied. It is shown that different carrier gas flow rates are required in order to obtain maximum sensitivities for different groups of elements, thus complicating the optimisation of ICP parameters. On the contrary, LA parameters have very similar effects on almost all elements studied, thus providing a common optimum parameter set for the entire mass range. However, for selected LA parameters, the use of compromise conditions was necessary in order to compensate for relatively slow data acquisition by ICP-MS and maintain high spatial resolution without sacrificing the multielemental capabilities of the technique. Possible variations in ablation efficiency were corrected for mathematically using the sum of Fe and Mn intensities. Quantification by external calibration against matrix-matched standards was successfully used for more than 50 elements. These standards, in the form of pressed pellets (no binder), were prepared in-house using ferromanganese concentrates from a deep-sea nodule reference material as well as from shallow-marine concretions varying in size and having different proportions of three major phases: aluminosilicates, Fe- and Mn-oxyhydroxides. Element concentrations in each standard were determined by means of conventional solution nebulisation ICP-MS following acid digestion. Examples of selected inter-element correlations in distribution patterns along the cross-section of a concretion are given.