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Analytical and Bioanalytical Chemistry (v.359, #4-5)

3. Symposium Massenspektrometrische Verfahren der Elementspurenanalyse 3rd Symposium on Mass Spectrometric Methods of Trace Elemental Analysis by H.-J. Dietze; J. S. Becker (pp. 307-308).

Applications of mass spectrometry in the trace element analysis of biological materials by Luc Moens (pp. 309-316).

The importance of mass spectrometry for the analysis of biological material is illustrated by reviewing the different mass spectrometric methods applied and describing some typical applications published recently. Though atomic absorption spectrometry is used in the majority of analyses of biological material, most mass spectrometric methods have been used to some extent for trace element determination in biomedical research. The relative importance of the different methods is estimated by reviewing recent research papers. It is striking that especially inductively coupled plasma mass spectrometry is increasingly being applied, partly because the method can be used on-line after chromatographic separation, in speciation studies. Mass spectrometric methods prove to offer unique possibilities in stable isotope tracer studies and for this purpose also experimentally demanding methods such as thermal ionization mass spectrometry and accelerator mass spectrometry are frequently used.

New strategies for trace analyses of ZrO2, SiC and Al2O3 ceramic powders by F. Kohl; N. Jakubowski; R. Brandt; C. Pilger; J. A. C. Broekaert (pp. 317-325).

The progress possible in the analysis of refractory powders such as ZrO₂, SiC and Al₂O₃ by the use of new sample preparation, processing and introduction techniques elaborated for AAS, ICP-OES and ICP-MS with low and high mass resolution is demonstrated. For optimized sample preparation techniques based on dissolution of ZrO₂, e.g. fusion with (NH₄)₂SO₄, it is shown to what extent impurities present in (NH₄)₂SO₄ determine the detection limit. Hydraulic high pressure nebulization with and without matrix removal by complexing the impurities with dithiocarbamates (Cu, Co, Cr and Ni) or oxine (Fe, Mn and Mo) and fixing them on a C₁₈ solid phase for subsequent solid phase extraction coupled with flame atomic absorption was used to determine Fe, Cu, Cr, Mn, Ni, Co and Mo impurities in (NH₄)₂SO₄ in the 10–100 ng/g range. Further a method to synthesize (NH₄)₂SO₄ with higher purity than some commercially available high-purity (NH₄)₂SO₄ with respect to Fe, Cu, Cr and Mn using high-purity NH₃ and chlorosulphonic acid is shown. Reliable determinations of Fe and Al at the 100 μg/g level in ZrO₂ with ICP-OES with matrix removal as well as with ICP-MS without matrix removal are reported. For the direct analysis of Al₂O₃ powders, slurry nebulization ICP-MS sample introduction is shown to improve detection limits and to reduce sample preparation, if the leachable and non-leachable fractions are analyzed separately. For powders such as SiC, the matrix or solvents can cause spectral interferences. Matrix removal is shown to be useful to improve detection limits for the interfered elements. High resolution ICP-MS can be used to control the completeness of matrix removal techniques and to overcome limitations due to spectral interferences even in case of complex materials.

Recent trends in solid mass spectrometry: GDMS and other methods by R. Gijbels; A. Bogaerts (pp. 326-330).

An overview is given of three mass spectrometric techniques that can be applied for solid analysis: spark source mass spectrometry (SSMS), glow discharge mass spectrometry (GDMS) and inductively coupled plasma mass spectrometry (ICP-MS). Some benefits and limitations, and some typical applications of these techniques are discussed.

Three-dimensional modeling of a direct current glow discharge in argon: is it better than one-dimensional modeling? by A. Bogaerts; Renaat Gijbels (pp. 331-337).

To obtain a better insight in the glow discharge, one-dimensional and three-dimensional models were developed for describing the behavior of the different species present in the discharge. In general, three-dimensional models are more complex and consume more computer time than one-dimensional models. To test whether it is really necessary to develop three-dimensional models or whether the one-dimensional approximation yields already a satisfactory description of the glow discharge, the results of both approaches have been compared. For the investigated cell geometry, the results are more or less comparable. Hence, one-dimensional models are in a first approximation sufficient to obtain a better insight in the glow discharge. However, three-dimensional models can give additional information (e.g., crater profiles at the cathode) and are therefore a progress when a more complete description of the discharge is intended.

Investigations on cluster and molecular ion formation by plasma mass spectrometry by J. S. Becker; H.-J. Dietze (pp. 338-345).

The formation of molecular and cluster ions of different inorganic materials in plasma mass spectrometry – spark source mass spectrometry (SSMS), radiofrequency glow discharge mass spectrometry (rf GDMS), laser ionization mass spectrometry (LIMS), inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) – was investigated and compared. Similar abundance distributions of cluster ions were observed for a graphite sample, for boron nitride/ graphite and for metal oxide/graphite mixtures using different plasma mass spectrometric methods. A correlation of intensities of metal argide ions in ICP-MS with their bond dissociation energies was used to estimate unknown dissociation energies of molecular ionic species. For the elements of the 2nd or 3rd period in the periodic table, the intensities of most argon molecular ions (ArX⁺) measured by ICP-MS rise with increasing atomic number in a similar manner to the theoretically calculated bond dissociation energies of argon molecular ions.

Development and application of ICP-MS in Elbe river research by R. Pepelnik; A. Prange; E. Jantzen; P. Krause; W. v. Tümpling (pp. 346-351).

In order to characterize the contamination of the river Elbe and generate elemental distribution patterns, up to fifty elements and additional alkylspecies of Sn, Hg and Pb have been determined in samples of suspended matter and sediment using inductively coupled plasma (ICP) – mass spectrometry (MS). The analytical results for the elemental concentrations have been compared with, and completed by those of other techniques such as instrumental neutron activation analysis (INAA), total reflection X-ray fluorescence spectrometry (TXRF) and ICP-optical emission spectrometry (OES). Sources of contamination are identified. The survey revealed groups of elements with similar behavior and groups of characteristic regional element patterns. Isotope ratio measurements have been used to characterize different sources of lead contribution.

Capabilities and limits of ICP-MS for direct determination of element traces in saline solutions by H. Falk; R. Geerling; B. Hattendorf; K. Krengel-Rothensee; K. P. Schmidt (pp. 352-356).

An ICP-MS method for the determination of ultra-traces of 24 Elements (Li, Be, Mg, Al, Cr, Mn, Co, Zn, Cu, Ga, As, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Ba, Tl, Pb, Bi, U) at ng/L to μg/L levels in highly saline solutions (up to 30 g/L NaCl) was developed. Calculated to the salt content of the samples, limits of detection at the sub-μg/kg level were obtained. This allows the measurement of samples like sea water, or clinical samples like urine, serum and whole blood, with few or without sample preparation and a drastic improvement to the limits of detection. Compared to the determination in solutions of 1 g/L NaCl the limits of detection in the original sample were improved by one order of magnitude. Improvements in instrumental stability are achieved by the use of an additional gas, that is introduced to the aerosol stream and avoids salt deposition in the aerosol tube of the torch, the use of High Matrix Content (HMC) cones, that show no clogging even at NaCl-concentrations up to 50 g/L. With this setup the long term stability for measurements with changing matrix concentrations is < 10% without and < 5% with use of an internal standard for the individual samples. Cleaning up is necessary after 2 days of operation. The direct analysis of the Nearshore Seawater Reference Material NRC-CNRC CASS3 showed a good agreement with the certified and measured concentrations. Elements, that do not suffer from an isobaric overlap of matrix compounds can be determined clearly at ng/L levels. Measurement of different matrix concentrations showed, that acceptable results can be achieved with a single calibration for concentrations from 5 g/L NaCl to 30 g/L NaCl, though matrix matching shows the best results.

ICP-MS – A powerful analytical technique for the analysis of traces of Sb, Bi, Pb, Sn and P in steel by Susanne Finkeldei; G. Staats (pp. 357-360).

The determination of Sb, Bi, Sn, Pb and P in steel using quadrupole- and double-focusing-sector-field-ICP-MS is described. Simple and fast methods for sample preparation were developed with regard to requirements of ICP-MS. Several certified steel reference materials were analyzed in order to verify the accuracy and precision of the applied methods.

Ultratrace analysis of calcium with high isotopic selectivity by diodelaser resonance ionisation mass spectrometry by K. Wendt; K. Blaum; B. A. Bushaw; F. Juston; W. Nörtershäuser; N. Trautmann; B. Wiche (pp. 361-363).

A resonance ionisation mass spectrometer for the ultratrace determination of calcium isotopes is presented. It achieves high overall efficiency, ultra-high isotopic abundance sensitivity of more than 10¹⁰ and complete suppression of isobars. The system can be used for isotope ratio studies on stable and long-lived trace isotopes with the final goal of radiodating via ⁴¹Ca-determination. For the different applications optical one-, two- or three-step resonance excitation and subsequent ionisation is applied using simple and inexpensive diodelasers. Additional mass analysis is accomplished in a commercial quadrupole mass spectrometer. The experimental set-up and first results on synthetical and meteorite samples are described.

Investigation of the binding properties of heavy-metal-peptide complexes in plant cell cultures using HPLC-ICP-MS by I. Leopold; Detlef Günther (pp. 364-370).

Metal-induced, sulfhydryl-rich peptides (phytochelatins) found in plants, algae, yeasts and fungi have been described as sequesters and detoxifiers of heavy metal ions. High-performance liquid chromatography (HPLC) coupled on-line with inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of heavy metal binding properties of phytochelatins in Silene vulgaris cell cultures. The induction of phytochelatins and the binding of heavy metals to these complexes were investigated by exposure of cell cultures with different concentrations of Cd, Cu, Pb and Zn. An in vitro heavy metal saturation assay and in vivo stress experiments with those elements able to bind to phytochelatins were carried out in order to characterize the binding affinity and binding stability of these compounds. It is shown that of the metals investigated, Cu binds most stably to phytochelatins under in vitro and in vivo conditions.

Investigation of the IC-ICP-MS determination of iodine species with reference to sample digestion procedures by H.-J. Stärk; J. Mattusch; R. Wennrich; A. Mroczek (pp. 371-374).

The determination of iodine in aqueous solutions suffers from several serious problems, caused by the formation of iodine species, derived from the oxidative pretreatment of biological materials. For the determination of these iodine species an ion chromatograph was coupled with an ICP-mass spectrometer. Because of the possible interconversion of the iodine species depending on the pH-value, different eluent-column combinations were used for acidic or alkaline sample solutions, respectively. Iodide, iodate, and several not identified, presumably organo-iodine species could be separated and detected. Unfortunately, the iodine (I₂) itself could not be determined with the method proposed. The reaction products of pretreatment are influenced strongly by the matrix. Mixtures of different iodine containing components are received, dependent on the matrix composition and particularly on the pH-value.

Identification of ground water contaminations by landfills using precise boron isotope ratio measurements with negative thermal ionization mass spectrometry by S. Eisenhut; K. G. Heumann (pp. 375-377).

Precise boron isotope ratio measurements with negative thermal ionization mass spectrometry were used for the identification of ground water contaminations by leakages of landfills. BO^- ₂thermal ions were produced to determine the ¹¹B/¹⁰B isotope ratio, which was expressed as δ¹¹B value in ‰ normalized to the standard reference material NIST SRM 951. For example, household waste influences the boron isotope ratio by specific components such as washing powder. In the case of one investigated landfill low δ¹¹B values correlate well with high boron concentrations in contaminated seepage water samples and vice versa for uncontaminated ground water samples. Possible boron contributions of rainwater were taken into account, determining a boron content of 2.3 μg/L and a δ¹¹B value of 13.1‰ for a representative sample. Such low boron concentrations were determined by isotope dilution mass spectrometry (detection limit 0.3 μg/L) whereas higher contents were also analyzed by a spectrophotometric method. However, different sources of contamination could only be identified by the isotope ratio and not by the concentration of boron.

Resonance ionization mass spectroscopy for trace determination of plutonium in environmental samples by N. Erdmann; G. Herrmann; G. Huber; S. Köhler; J. V. Kratz; A. Mansel; M. Nunnemann; G. Passler; N. Trautmann; A. Turchin; A. Waldek (pp. 378-381).

Resonance ionization mass spectroscopy (RIMS) is a sensitive and isotope selective method and well suited for trace analysis of plutonium in the environment. After the chemical isolation of plutonium from soil, air filters or urine, e.g., it is electrolytically deposited as hydroxide on a tantalum backing and covered with a thin titanium layer. By heating such a sandwich filament in the RIMS-apparatus under vacuum an atomic beam of plutonium is produced. The atoms are ionized by a three-step resonant excitation using pulsed dye lasers, and the ions are mass-selectively detected with a time-of-flight (TOF) spectrometer and a multi channel plate detector. RIMS yields a low detection limit of 10⁶–10⁷ atoms and a high element and isotope selectivity. This technique has been used for the investigation of soil samples from the Chernobyl area, sediments from the Mururoa Atoll and urine samples with respect to the total amount of plutonium and its isotopic composition.

Determination of lead concentrations and isotope ratios in recent snow samples from high alpine sites with a double focusing ICP-MS by T. Döring; M. Schwikowski; H. W. Gäggeler (pp. 382-384).

A double focusing ICP-MS, equipped with a Micro Concentric Nebulizer, has been used to determine concentrations and isotopic ratios of lead in recent snow samples (1993–1996) from high alpine sites in Switzerland. Concentrations varied between 0.02 ± 0.002 and 5.5 ± 0.15 ng/g and are slightly lower than concentrations reported by Atteia [1], by Batifol et al. [2], and by Wagenbach et al. [3] for precipitation samples from similar remote sites in Europe. Since concentrations of lead in the fresh snow samples were mainly in the lower pg/g range, the method to determine the isotopic ratios ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb had to be optimized. They could finally be determined with an average standard error of 0.14% within 12 min and a total sample consumption of 0.8 mL. The average ratios ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb were 0.875 and 2.117, respectively. These values are comparable to isotopic compositions of lead in aerosols collected in Western Europe [4] and are less radiogenic than predicted by Grousset et al. [5]. Our data indicate that, although lead emissions from traffic have decreased largely during the last 10 years, the contribution from this source in modern snow is still detectable and seems to be equal to the lead input from other anthropogenic sources (e.g. waste incineration, industry).

Multi-ion counting-spark source mass spectrometry (MIC-SSMS): A new multielement technique in geo- and cosmochemistry by K. P. Jochum; H.-J. Laue; H. M. Seufert; C. Dienemann; B. Stoll; J. Pfänder; M. Flanz; H. Achtermann; A. W. Hofmann (pp. 385-389).

The photoplate detection system of a spark source mass spectrometer has been recently replaced by a detector array consisting of 20 separate small channeltrons for simultaneous ion counting of up to 20 trace elements. The new multi-ion counting – spark source mass spectrometry (MIC-SSMS) technique combines the advantages of conventional SSMS with modern on-line detection of elements. It has important analytical features, such as simple and fast solid-state sample preparation, high precision (about 1–2%) and accuracy (4%) using multielement isotope dilution, high sensitivity which leads to short measuring times (10–50 min) and low detection limits (about 0.001–0.01 μg/g).

Direct liquid ablation: a new calibration strategy for laser ablation-ICP-MS microanalysis of solids and liquids by D. Günther; R. Frischknecht; H.-J. Müschenborn; C. A. Heinrich (pp. 390-393).

Trace elements in microliter quantities of aqueous solutions were analysed by direct liquid ablation using an 193 nm excimer with an inductively coupled plasma mass spectrometer (ICP-MS). Fractionation resulting from splashing and evaporation can be minimised by covering the liquid surface with a thin plastic film, through which a 20 μm hole is drilled with the laser. Particle-size distribution and oxide formation in the plasma resulting from the direct liquid ablation are similar to those generated by solid ablation. The ICP-MS response in cps/ppm is approximately 100 × higher for the direct ablation, but is proportional to the response from solid ablation, within an accuracy < 15% for most trace elements in NIST 610 and NIST 612 glass standards. A matrix load up to 2.5 wt.-% NaCl in the solution does not affect the proportionality of trace element responses. Thus, direct liquid ablation is not only suited for analysing small volumes of complex aqueous solutions (e.g., the quantitative microanalysis of fluid inclusions in minerals), but also provides a new approach for calibrating laser ablation ICP-MS microanalysis of solids.

Is laser-ablation-ICP-MS an alternative to solution analysis of solid samples? by E. Hoffmann; C. Lüdke; H. Scholze (pp. 394-398).

The basic obstacles for the general use of laser-ablation(LA)-ICP-MS in analytical laboratories are connected with its reproducibility and calibration. A mathematical relation deduced from the correlation function of the analytical signals allows the estimation of the number of craters needed for representative analyses. The procedure was applied to different samples such as manganese crusts and soils. The ion intensities of the major elements in the manganese crusts and nodules were used as internal standards, improving relative standard deviations by factors between 2 and 3. Selected samples of wood and manganese crusts were analyzed by LA-ICP-MS and the results compared with those obtained by solution ICP-MS. The agreement of the values is within the 95% confidence limits. Powdered reference materials and, in the case of wood analysis, cellulose doped with standard solutions were used for the calibration.

Determination of trace-metal concentrations in size-classified atmospheric particles by ETV-ICP-MS by C. Lüdke; E. Hoffmann; J. Skole (pp. 399-403).

Atmospheric particles were sampled and fractionated according to their size by a cascade impactor in Berlin, capital city of Germany, on the Brocken, peak of the Harz mountains and on the Szrenica peak in the Giant mountains, Republic Poland. The fractionated particles were collected on small graphite targets and subsequently analyzed by ETV-ICP-MS. Distribution curves were measured showing trace-metal contents in air versus the aerodynamic particle diameter for the elements Pb, Ag, Cd and Tl. Despite good element correlation, the distribution curves differ significantly for the three sampling locations. The limits of detection for the elements of concern were in the pg/m³ range at a sampling time of 4 h. An attempt was made to determine single particles: in urban aerosols a content was found of 1 · 10^–13 g Tl and 9 · 10^–13 g Ag in single particles of the size fraction < 7.5 μm and > 3.45 μm.

Determination of impurities in micro-amounts of silver alloys by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) after in-situ-digestion in the graphite furnace by C. Moor; Peter Boll; Sonja Wiget (pp. 404-406).

Forgeries of antique silver objects can be identified by their fingerprints of impurities. The dissolution of the samples causes severe problems since Au and Ag have to be dissolved simultaneously. In order to overcome that difficulty and to minimize the amount of sample, an ETV-ICP-MS method is presented based on solid sampling and an in-situ-digestion with nitric acid in a graphite tube. Determinations of Au, Bi, Cd, Pb, Sb, Sn and Zn were performed in a range of 10 μg/g–1% and with an accuracy of 10%–50%. Less than 1 mg sample material is required.

Isotopic and ultratrace analysis of uranium by double-focusing sector field ICP mass spectrometry by W. Kerl; J. S. Becker; H.-J. Dietze; W. Dannecker (pp. 407-409).

An analytical method for the ultratrace and isotopic analysis of uranium in radioactive waste samples using a double-focusing sector field ICP mass spectrometer is described. In high-purity water a detection limit for uranium in the lowest fg/mL range has been achieved. Under optimum experimental conditions (²³⁵U/²³⁸U ≈ 1), the precision in ²³⁵U/²³⁸U isotopic ratio determinations has been determined as 0.07% RSD. With the isotopic standard U-020 (²³⁵U/²³⁸U = 0.0208) a precision of 0.23% RSD at the 100 pg/mL level using ultrasonic nebulization has been achieved. With ²³⁴U/²³⁸U isotopic ratios of down to 10^–5, the values obtained by double-focusing sector field ICP-MS and alpha spectrometry were in agreement.

Trace element determination of high-purity chemicals for the processing of semiconductors with high-resolution ICP-mass spectrometry using stable isotope dilution analysis (IDA) by J. Dahmen; M. Pfluger; M. Martin; L. Rottmann; G. Weichbrodt (pp. 410-413).

The demand for trace element analysis in many fields of application has significantly increased in the last few years. Accuracy is fundamental to analysis and the importance of accurate measurements is widely accepted. Yet most instrumental analytical methods are relative methods and accuracy is established by using certified reference materials for method validation and calibration or by use of a definitive method as isotope dilution analysis (IDA). In this work a new high-resolution ICP mass spectrometer Finnigan MAT “ELEMENT”, which provides mass spectral resolution of 300 up to 7500 and thus eliminates most of the spectral interferences quadrupol mass analyzers are suffering from, is applied in combination with IDA to evaluate the capabilities of these techniques to the accurate determination of element traces in processing chemicals for semiconductor production.

Uranium determination in process chemicals: on the way to sub-pg/g concentrations by Dirk Wollenweber; H. Wildner; Gerold Wünsch (pp. 414-417).

The detection limit of ICP-MS is affected by the sensitivity, the height of the blank and its relative stability i.e. precision, the accuracy and additionally by a bias or systematical error. The improvement of a single factor will improve the efficiency of the whole analytical system. For the example of uranium determination in process chemicals such as concentrated HF and HNO₃ the improvement or deterioration of the factors given above is demonstrated. The applied methods are matrix removal by evaporation, highly efficient nebulization with a USN, isotope dilution and use of a double-focusing instrument (ICP-SFMS_LR). The increase or decrease of each factor is compared to conventional nebulization ICP-QMS. To take full advantage of each single method, they can be combined with each other. Possible drawbacks of a single method are compensated by another method. Detection limits for uranium in concentrated process chemicals in the sub-pg/g range can be achieved.

Investigations concerning the analysis of high-purity metals (Cd, Cu, Ga and Zn) by high resolution inductively coupled plasma mass spectrometry by R. Matschat; M. Czerwensky; M. Hamester; S. Pattberg (pp. 418-423).

High resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) in combination with a micro concentric nebulizer was studied in order to evaluate its suitability for the certification of the content of trace elements in high-purity metals. About 30 trace elements (analytes) were determined using solutions of high-purity Cd, Cu, Ga and Zn. The concentration levels of these matrices were varied as an experimental parameter. HR-ICP-MS was demonstrated to be very versatile and of high analytical performance. Effects of matrix concentrations on the analytical sensitivities and on the detection limits were investigated to find out optimal working conditions and to distiguish between different sources of matrix influences on sensitivities. As an example the gallium matrix was studied to obtain information about the matrix depositions on the cones of the mass spectrometer inlet system, using scanning electron microscopy and spectroscopical methods, including Raman spectroscopy.

Trace analysis of metals in plant samples with inductively coupled plasma – mass spectrometry by M. Leiterer; J. W. Einax; C. Löser; A. Vetter (pp. 423-426).

An analytical method for the quantitative determination of Al, Ti, V, Cr, Co, Ni, Cu, Zn, Mo, Cd, Ti and Pb in plant samples by ICP-MS has been developed. Spectral interferences, plant matrix effects, precision and accuracy are discussed. Results are demonstrated for selected samples concerned with the mass balance of heavy metals after utilization of non-food vegetable materials in a power plant.

Determination of physiological palladium and platinum levels in urine using double focusing magnetic sector field ICP-MS by J. Begerow; Martina Turfeld; Lothar Dunemann (pp. 427-429).

A new extremely sensitive method for the determination of physiological (normal) Pd and Pt levels in human urine is presented, applying UV photolysis followed by sequential determination with double focusing magnetic sector field ICP-MS. Due to the low blank values, which are a consequence of the minimal reagent addition required, UV photolysis turned out to be advantageous for the decomposition of the organic matrix. Sector field ICP-MS operating in the low resolution (LR) mode permits detection limits for Pt and Pd which are distinctly lower than in the high resolution (HR) mode or with quadrupole instruments when using a comparable sample introduction system. The practical detection limits in urine were 0.17 ng/L Pd and 0.24 ng/L Pt using standard nickel cones. Taking into account a dilution factor of 4.2, the detection limits related to the final solution were 0.04 ng/L Pd and 0.06 ng/L Pt. The use of a high-performance nickel skimmer cone did not result in any improvement of the detection limits because the signal of the analytes and the background were enhanced to a similar extent. Urinary Pd levels in 21 unexposed persons ranged from 32.7 to 219.7 ng/L (arithmetic mean (AM): 140.3 ng/L), the Pt levels were between 0.48 and 7.7 ng/L (AM: 1.8 ng/L). The relevance and severity of mass spectral interferences in the Pd and Pt determination at these concentration levels have been investigated.

Determination of halogen species of humic substances using HPLC/ICP-MS coupling by Gunther Rädlinger; K. G. Heumann (pp. 430-433).

A mass spectrometric method for the determination of chlorine, bromine and iodine species of humic substances (HS) has been developed by coupling a HPLC system with ICP-MS. Using size exclusion chromatography, the method was applied to the characterization of natural water samples (ground water, seepage water from soil, brown water) and a sewage water sample. Quantification of iodine/HS species was carried out by the on-line isotope dilution technique, which was not possible for bromine and chlorine species because of mass spectroscopic interferences by using a quadrupole ICP-MS. Characteristic fingerprints of the halogen/HS species, correlated with the corresponding UV chromatogram, were obtained dependent on the different origin of HS. Biological influences were indicated when following changes of the iodine/HS species composition by aging. The formation of iodine/HS species from inorganic iodide was investigated by labelling experiments with an ¹²⁹I^– spike solution, resulting in the finding that specific HS fractions are preferably iodinated.

Arsenic compounds in a marine food chain by W. Goessler; W. Maher; K. J. Irgolic; D. Kuehnelt; C. Schlagenhaufen; T. Kaise (pp. 434-437).

A three-organism food chain within a rock pool at Rosedale, NSW, Australia, was investigated with respect to arsenic compounds by high performance liquid chromatography – hydraulic high pressure nebulization – inductively coupled plasma mass spectrometry (HPLC-HHPN-ICP-MS). Total arsenic concentration was determined in the seaweed Hormosira banksii (27.2 μg/g dry mass), in the gastropod Austrocochlea constricta (74.4 μg/g dry mass), which consumes the seaweed, and in the gastropod Morula marginalba (233 μg/g dry mass), which eats Austrocochlea constricta. The major arsenic compounds in the seaweed were (2′R)-dimethyl[1-O-(2′,3′-dihydroxypropyl)-5-deoxy-β-d-ribofuranos-5-yl]arsine oxide and an unidentified compound. The herbivorous gastropod Austrocochlea constricta transformed most of the arsenic taken up with the seaweed to arsenobetaine. Traces of arsenite, arsenate, dimethylarsinic acid, arsenocholine, the tetramethylarsonium cation, and several unknown arsenic compounds were detected. Arsenobetaine accounted for 95% of the arsenic in the carnivorous gastropod Morula marginalba. In Morula marginalba the concentration of arsenocholine was higher, and the concentrations of the minor arsenic compounds lower than in the herbivorous gastropod Austrocochlea constricta.

Determination of heavy metal complexes with humic substances by HPLC/ICP-MS coupling using on-line isotope dilution technique by Jochen Vogl; K. G. Heumann (pp. 438-441).

An isotope dilution mass spectrometric (IDMS) method has been developed for the simultaneous determination of the complexes of 11 heavy metals (Ag, Cd, Cu, Mo, Ni, Pb, Tl, U, W, Zn and Zr) with humic substances (HS) by coupling HPLC with ICP-MS and applying the on-line isotope dilution technique. The HPLC separation was carried out with size exclusion chromatography. This HPLC/ICP-IDMS method was applied to samples from a brown water, ground water, sewage and seepage water as well as for a sample containing isolated fulvic acids. The total contents of heavy metals and of their complexes were analyzed in these samples with detection limits in the range of 5–110 ng/L. The analysis of heavy metal/HS complexes from the different waters resulted in characteristic fingerprints of the distribution pattern of heavy metals in the separated HS fractions. A comparison between the total heavy metal concentrations and their portions bound to humic substances showed distinct differences for the various metals. Simultaneous ¹²C detection was used for the characterization of HS complexes not identified by UV detection and for the determination of relative DOC concentrations of chromatographic peaks.

Employing multivariate calibration for the determination of radionuclides by inductively coupled plasma-mass spectrometry by M. Rupprecht; T. Probst (pp. 442-445).

A method for the simultaneous ICP-MS determination of α- and β-emitting radionuclides in acid digested samples of concrete without further sample pretreatment is presented. Spectral and non-spectral interferences are corrected for by combining systematic internal standardization with bilinear multivariate calibration. Consequently, especially for radionuclides with long half-lives, ICP-MS is an alternative to radiometric analytical methods. The optimal multivariate calibration approach is the PLS1-model with preselected variables.

Stable isotope labels as a tool to determine the iron absorption by Peruvian school children from a breakfast meal by T. Walczyk; Lena Davidsson; Nelly Zavaleta; Richard F. Hurrell (pp. 445-449).

Fractional iron absorption from a breakfast meal was determined in Peruvian children employing stable iron isotopes as labels. Iron isotopic analysis was performed by the recently developed negative thermal ionization technique for high-precision iron isotope ratio measurements using FeF₄ ^– ions. By increasing the ascorbic acid content of the standard breakfast meal as served within the Peruvian school-breakfast program from 27 mg to 70 mg, it was possible to increase the geometric mean fractional iron absorption significantly from 5.1% (range 1.6–13.5%) to 8.2% (range 3.1–25.8%). Fractional iron absorption was calculated according to isotope dilution principles and by considering the non-monoisotopic character of the used spikes.

Trace analysis of glasses by magnetically enhanced rf GDMS by A. I. Saprykin; J. S. Becker; H.-J. Dietze (pp. 449-453).

A radiofrequency (rf) glow discharge ion source coupled to a commercial double-focusing mass spectrometer was used for the direct trace element analysis of glass samples. By utilizing an additional ring-shaped magnet located behind the flat sample in an rf glow discharge ion source compared with a configuration without a magnet, the sputtering and ionization efficiency of glass samples was enhanced and the detection power for trace elements was improved. The detection limits for elements determined by rf glow discharge mass spectrometry at low mass resolution (m/Δm = 300) are 10–100 ng/g. Possible interferences of atomic ions of analyte and molecular ions which limited the determination of some elements (e.g. Ti, Mn, Fe, Ni, Co, Cu, Zn) could be resolved at the mass resolution of m/Δm = 3000. The detection limits for these elements were found to be about 100 ng/g. Relative sensitivity factors (RSFs) for all elements of interest with respect to Sr (internal standard element) were determined in the range of 0.2–3.

Trace element analysis of geological glasses by laser plasma ionization mass spectrometry (LIMS): A comparison with other multielement and microanalytical methods by H. M. Seufert; K. P. Jochum (pp. 454-457).

Laser plasma ionization mass spectrometry (LIMS) is used in our laboratory as an in-situ microanalytical method for the investigation of solids, especially of rocks and minerals. To demonstrate the accuracy of this method we have analyzed homogeneous geological glass samples. The results are compared with data obtained from other analytical techniques. The performance of the LIMS method for geochemical investigations is discussed.

Microanalysis of minerals by laser ablation ICPMS and SIRMS by K. Simon; U. Wiechert; J. Hoefs; B. Grote (pp. 458-461).

Due to permanent re-equilibration processes that minerals undergo during dynamic processes within the earth, minerals build up concentration profiles – mainly from rim to core – which are ideal indicators of the geological processes the rocks have suffered. To understand these fingerprints of geological processes micro-analytical facilities are required that allow measurement of the isotopic and chemical composition of spot sizes from about 1 μm to 1 mm at concentration levels in the ng/g-range. Laser ablation techniques combined with inductively coupled plasma mass spectrometry (LA-ICPMS) and stable isotope ratio mass spectrometry (SIRMS) recently have achieved these demands. This contribution gives an example about their potential in establishing concentration gradients within minerals for geological questions.

High resolution-ICPMS in fast scanning-mode: application for laser ablation analysis of zircon by C.-D. Garbe-Schönberg; Thomas Arpe (pp. 462-464).

The general applicability of a double focusing sector field high resolution-inductively coupled mass spectrometry (HR-ICPMS) is evaluated for the precise and accurate determination of the abundances of rare earth elements (REE) in zircon by LA-ICPMS using a 266 nm UV-laser. “Zircon 91500”, a recently released new reference material for microanalytical work but with contradictory REE data is investigated with both the 266 nm laser and a 1024 nm IR-laser coupled to a quadrupole ICPMS. The data show evidence for a homogeneous distribution of the heavy REE. In contrast, in some “Zircon 91500” chips the trace elements Hf, Th, U are inhomogeneously distributed.

An investigation of different modifiers in electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) by K. Grünke; H.-J. Stärk; R. Wennrich; H. M. Ortner; J. A. C. Broekaert (pp. 465-468).

The suitability of eleven modifiers (Pd-, Mg-, K-, Ca- and NH₄-salts) for electrothermal vaporization coupled to inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the determination of Mn, Cu, Zn, Cd and Pb has been studied. Solutions containing varying quantities (10–2000 ng absolute) of these salts have been added to four different amounts of analyte to study their suitability as modifier and their mass dependent influence. The best sensitivity enhancement for all elements tested was achieved with IrCl₃ and PdCl₂. From a comparison of the effect of PdCl₂ vs. Pd(NO₃)₂ it could be concluded that the mechanism of matrix modification also depends on the chemical form of the modifier. Particularly, for the volatile elements Cd and Zn differences in the behavior of the different chemical compounds of one metal (e.g. Pd) is evident, which shows that the enhancement effect is a result of the stabilization of the analytes in the graphite tube prior to vaporization and the improvement of the transport efficiency after vaporization.

Trace element analysis of sediments by HR-ICP-MS using low and medium resolution and different acid digestions by B. Schnetger (pp. 468-472).

For the multielement analysis of sediments (Li, Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Mo, Cd, Sn, Sb, Cs, Ba, lanthanides, Hf, Tl, Pb, Bi, Th, U) a dissolution with a hydrofluoric - sulfuric - nitric acid mixture, subsequent evaporation of the acids, dissolution of the residue by HCl, evaporation of the acid and redissolution of the residue by HNO₃ is a useful procedure which allows the dissolution of a wide range of mineral mixtures. An ICP-MS was used for the determination of the elements. For Cr, Ni, Cu and Zn the analysis may be complicated by the interferences of sulfur or chlorine species, which remain in the solution during dissolution. The best analytical results for these elements can be achieved in the medium resolution mode of a HR-ICP-MS. In the low resolution mode (quadrupole instrument characteristics) the determination of these elements should be performed by the isotopes of ⁵²Cr, ⁶²Ni, ⁶³Cu, ⁶⁸Zn as it was found that interferences from remaining acids are of minor importance.

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Analytical and Bioanalytical Chemistry (v.359, #4-5)

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Analytical and Bioanalytical Chemistry (v.359, #4-5)