Determination of heavy metals in TiO2 with isotope dilution mass spectrometry

An isotope dilution mass spectrometric (IDMS) method has been developed for the determination of trace impurities (Fe, Cu, Cr, Ni, Cd, Pb, Tl, and U) in TiO₂; this is of special interest for the quality control of this pigment substance. The measurement of the isotope ratios was carried out using a compact thermal ionization quadrupole mass spectrometer by producing positive thermal ions. For the dissolution of the sample, microwave digestion with HF was applied. Different separation techniques (ion exchange chromatography, extraction, electrolytic deposition) were used for the trace/matrix separation and the element specific isolation of the different trace elements to be determined. The detection limits obtained were (in ng/g): Fe=90, Cu=11, Ni=8, Cd=7, Pb=26, Tl=0.6, U=0.2. Because IDMS usually results in accurate analytical results, this method can best be used for calibration of other analytical methods, or for the certification of corresponding standard reference materials.     

Comparison of heavy metal analyses in hydrofluoric acid used in microelectronic industry by ICP-MS and thermal ionization isotope dilution mass spectrometry

An isotope dilution mass spectrometric (IDMS) method with the thermal ionization (TI) technique has been developed for the determination of trace impurities of Cr, Fe, Ni, Cu, Zn, Ag, Cd, Tl, Pb, Th, and U in high-purity HF (50% by weight) used in the semiconductor industry. The evaporation step of the HF solution was carried out in an apparatus which did not significantly contribute to contaminations of the heavy metals to be analysed. This apparatus allowed fast evaporation of the HF solution of up to 200 ml/h and therefore also a fast trace heavy metal/matrix separation was carried out. The evaporation step was also used in connection with inductively coupled plasma mass spectrometry (ICP-MS) when applying the isotope dilution technique and an external calibration for quantification, respectively. The detection limits for TI-IDMS were (in pg/g): Cr=30, Fe=400, Ni=70, Cu=20, Zn=1100, Ag=70, Cd=10, Tl=1, Pb=16, Th=3, and U=1. With ICP-MS in combination with the evaporation step, detection limits of less than 50 pg/g have been achieved for Cr, Ni, and Zn and of <5 pg/g for the other elements except Fe, which could not be determined in concentrations less than 100 ng/g. On the other hand, the detection limits were much higher when the HF matrix was not removed before measuring by ICP-MS. A comparison of the different ICP-MS methods (isotope dilution technique and external calibration for both HF evaporated samples and those with HF matrix) with the results of TI-IDMS has been carried out. An excellent agreement was achieved between the results of TI-IDMS and the two ICP-MS methods using the HF evaporation step, whereas the ICP-MS techniques without HF evaporation essentially deviated from these results. Fe was the only trace element of all investigated heavy metals which could only be analysed by TI-IDMS in high purity HF in a concentration of about 3 ng/g. Although ICP-MS with isotope dilution and external calibration resulted in comparable analytical data, the ICP-IDMS method has some practical advantages such as time-saving and more reliable results.     

Ultra-trace analysis of U,Th, Ca and selected heavy metals in high purity refractory metals with isotope dilution mass spectrometry

A method for the determination of trace impurities (U, Th, Ca, Fe, Cr, Ni, Cu, and Cd) in the refractory metals molybdenum and tungsten with isotope dilution mass Spectrometry (IDMS) has been developed. This method enables determinations of uranium and thorium down to the lowest pg/g level with high precision and accuracy. Selective chromatographic, extractive and electrolytic methods for the trace-matrix separation were combined with positive thermal ionization mass spectrometry. Different samples of high purity (4N) and of ultra high purity (UHP) materials for advanced technologies were analysed. The detection limits reached are (in ng/g): U 0.006, Th 0.008, Ca 10, Fe 19, Cr 0.5, Ni 0.6, Cu 2.7, and Cd 0.12. A comparison of results with other sensitive analytical methods (ICP-MS, GDMS, SIMS) makes obvious the urgent necessity of a reliable calibration method like IDMS because the analytical results obtained by the other methods often spread over a wide range.     

Isotope dilution mass spectrometry of microelectronically relevant heavy metal traces in high-purity cobalt

Summary Because cobalt and its silicides are increasingly used in microelectronic devices, an isotope dilution mass spectrometric (IDMS) method has been developed for trace analysis of relevant heavy metals (U, Th, Fe, Zn, Tl, and Cd) in high-purity cobalt. The measurements of the isotope ratios were carried out with a small thermal ionization quadrupole mass spectrometer by producing positive thermal ions in a single- or double-filament ion source. For the trace/matrix separation and the isolation of the different heavy metals, anion-exchange chromatography and an extraction method for iron were applied. The detection limits obtained were (in ng/g): U=0.007, Th=0.017, Tl=0.06, Cd=1, Zn=8, and Fe=11, which demonstrates that the particularly critical radioactive impurities uranium and thorium could be analysed down to the low pg/g range. Three cobalt samples of different purity were analysed with concentrations ranging from about 0.1 ng/g for U and Th in an ultra high-purity material produced for microelectronic purposes, up to about 70 g/g for Cd in a cobalt sample with declared purity of 99.8%. Because IDMS usually results in accurate analytical results, it can be used in the future for calibration of other methods like glow discharge mass spectrometry, as could be shown by analysing one cobalt sample by both methods. IDMS can also be applied for the production of urgently needed certified standard reference materials in this important field of high technology.Presented at the ANAKON '93 conference     

Investigations of trace elements in high salinity waters by ICP-MS

A separation and enrichment procedure for the analysis of trace elements (Cd, Co, Cu, Fe, Mn, Ni, Pb, Tl, U, Zn) in seawater or brines from ore dumps by ICP-MS was established based on the complexation with sodium diethyldithiocarbamate-trihydrate (Na-DDTC) and separation on a phenyl column. The method was tested with seawater samples from the hydrothermal system of Axial Seamount, Juan de Fuca Ridge. The analytical results demonstrated the influence of hydrothermal activity on the concentration of Fe and Mn. Received: 2 December 1998 / Revised: 25 February 1999 / Accepted: 1 March 1999     

Investigations of trace elements in high salinity waters by ICP-MS

A separation and enrichment procedure for the analysis of trace elements (Cd, Co, Cu, Fe, Mn, Ni, Pb, Tl, U, Zn) in seawater or brines from ore dumps by ICP-MS was established based on the complexation with sodium diethyldithiocarbamate-trihydrate (Na-DDTC) and separation on a phenyl column. The method was tested with seawater samples from the hydrothermal system of Axial Seamount, Juan de Fuca Ridge. The analytical results demonstrated the influence of hydrothermal activity on the concentration of Fe and Mn. Received: 2 December 1998 / Revised: 25 February 1999 / Accepted: 1 March 1999     

Application of isotope dilution mass spectrometry to research of certified reference materials

This paper briefly describes the method and applications of isotope dilution mass spectrometry(IDMS). Primary standard solutions with various natural isotope abundances were used to certify the concentration of enriched isotope solutions by IDMS. Then these enriched isotopes were used to certify unknown samples by IDMS. Li, K, Mg, Fe, Cu, Ni, Cd, Mo, Pb, etc in CRMs were certified and very good results were obtained in three international comparisons by IDMS. Received: 15 June 2000 Accepted: 26 October 2001     

Determination of heavy metals at the pg/g level in Antarctic snow with DPASV and IDMS

Summary Differential pulse anodic stripping voltammetry (DPASV) and isotope dilution mass spectrometry (IDMS) were used to analyse heavy metals in Antarctic snow samples. It was possible to determine Pb and Cd with DPASV at the German Antarctic station Georg-von-Neumayer whereas the analyses of Pb, Cd, Tl, Cr, Ni, Cu, Zn, and Fe with IDMS were carried out at the University of Regensburg. 80% of the elemental concentrations in surface snow samples analysed with IDMS lay in the following ranges: Pb=3–40 pg/g, Cd<0.2–3 pg/g, Tl<0.2 pg/g, Cr<0.8–15 pg/g, Ni<4.8–40 pg/g, Cu<11–30 pg/g, Zn=30–500 pg/g, and Fe=(0.5–1.5)×10³ pg/g. In most cases an acceptable agreement between the DPASV and IDMS results was obtained for Pb and Cd. More than 50% of all Pb analyses agreed within a deviation of 0–10 pg/g. The Cd results between both methods usually deviated by less than 1 pg/g. Slightly higher Pb concentrations were analysed in the average with IDMS compared with DPASV. This effect was not observed for the Cd data. A possible explanation for this fact are non-ionic Pb species in the melted snow samples, which cannot be analysed by DPASV. One particular investigation of Pb concentrations showed that the analysed data with DPASV decreased with the increasing length of sun-shine after a snowfall when samples of the same origin were determined. Blank control is the major requirement for accurate analysis results of heavy metals in this low concentration range. On the other hand, accuracy must always be tested by independent analytical methods. In this work it is shown that Pb and Cd can be analysed directly in the Antarctica with DPASV and that the result of this method is in acceptable agreement with the definitive method IDMS.

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Bestimmung von Schwermetallen im pg/g Bereich in antarktischen Schneeproben durch differentielle Pulsinversvoltammetrie und massenspektrometrische Isotopenverdünnungsanalyse

     

A critical comparison of on-line coupling IC-ICP-(AES, MS) with competing analytical methods for ultra trace analysis of microelectronic materials

On-line coupling of ion chromatography and atomic spectrometry (IC-ICP-(AES, MS)) are compared to so-called reference methods and other competing methods for ultra trace characterization of solid microelectronic materials. The comparison is based on analytical data gained for well characterized samples by a number of different laboratories. The matrices used for comparison are Mo, Mo-oxide, MoSi_x, W, W-oxide, WSi_x, metallic As, red P and Re. The analyte elements accessible by IC-ICP-(AES, MS) and with reference values for at least one other method are Ag, Al, Ba, Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Ti, Tl, Th, U and Zn. The agreement of results of IC-ICP-(AES, MS) with those of isotope dilution mass spectrometry (IDMS) and radiochemical activation analyses (RNAA) shows good accuracy for most elements and some contamination problems with ubiquitous elements. A correlation of IC-ICP-(AES, MS) and GDMS results is undoubtful, but the discrepancies are rather high. As further technique ETV-ICP-MS is compared, whose results are in reasonable agreement with IC-ICP-(AES, MS). Details on some new applications as well as of some new methodological enhancements of on-line coupling IC-ICP(AES, MS) for the matrices As and P were included.     

Determination of heavy metals (Pb, Cd, Cu, Zn, Cr) in sedimentary reference materials with IDMS: total concentration and aqua regia soluble portion

Summary The total concentration and the aqua regia soluble portion of traces of Pb, Cd, Cu, Zn, and Cr are determined with isotope dilution mass spectrometry (IDMS) in three different types of sediments using a thermal quadrupole instrument (THQ). The results are compared with those obtained by other methods during a certification project to establish these sediments (BCR 277, BCR 280, BCR 320) as standard reference materials. The IDMS (THQ) results are in good agreement with the preliminary certification values and the results of two other laboratories, which applied IDMS using magnetic sector field mass spectrometers. Significant differences between the different analytical methods were found for the total Pb concentration, which could be explained by adsorption and coprecipitation effects during the chemical pretreatment of samples. Using aqua regia instead of HF/HNO₃ for the decomposition of sediments, only 65%–95% of the total Pb and 60%–90% of the total Cr could be dissolved. On the other hand, only a small or negligible portion of Zn, Cd, and Cu could not be dissolved by aqua regia. The IDMS values for the aqua regia soluble Cr portion are significantly higher compared to the results of other methods. This can be explained by adsorption effects.

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Bestimmung von Schwermetallen (Pb, Cd, Cu, Zn, Cr) in sedimentären Standard-Referenzmaterialien mit massenspektrometrischer Isotopenverdünnungsanalyse: Totalgehalt sowie in Königswasser löslicher Anteil

     

SI-traceable certification of the IMEP-12 water sample combining contributions from different reference laboratories

In the International Measurement Evaluation Programme (IMEP-12) comparison, a synthetically prepared water sample was offered to the analytical laboratories to perform measurements of As, B, Cd, Cr, Cu, Fe, Mg, Mn, Ni and Pb. The choice of elements to be measured was based on EU legislation, which the comparison was aiming to support. As to the IMEP policy, the laboratories’ results were presented according to the certified/assigned reference values established by several reference laboratories all around the world. The performed certification campaign is described in detail in this paper. Isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement (PMM), whenever possible, to achieve SI-traceable results. Apart from IDMS for reference measurements of some elements, k _o-neutron activation analysis (k _o-NAA) and external calibration (Ext-Calib) using inductively coupled plasma-mass spectrometry (ICP-MS) were applied. The reference values were characterised as “certified” (for B, Cd, Cr, Cu, Fe, Mg, Ni and Pb) or “assigned” (for As and Mn) according to the IMEP policy. Measurement uncertainty of the certified/assigned reference values was calculated according to the ISO/BIPM guide using the specialised software GUM Workbench.     

SI-traceable certification of the IMEP-12 water sample combining contributions from different reference laboratories

In the International Measurement Evaluation Programme (IMEP-12) comparison, a synthetically prepared water sample was offered to the analytical laboratories to perform measurements of As, B, Cd, Cr, Cu, Fe, Mg, Mn, Ni and Pb. The choice of elements to be measured was based on EU legislation, which the comparison was aiming to support. As to the IMEP policy, the laboratories’ results were presented according to the certified/assigned reference values established by several reference laboratories all around the world. The performed certification campaign is described in detail in this paper. Isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement (PMM), whenever possible, to achieve SI-traceable results. Apart from IDMS for reference measurements of some elements, k _o-neutron activation analysis (k _o-NAA) and external calibration (Ext-Calib) using inductively coupled plasma-mass spectrometry (ICP-MS) were applied. The reference values were characterised as “certified” (for B, Cd, Cr, Cu, Fe, Mg, Ni and Pb) or “assigned” (for As and Mn) according to the IMEP policy. Measurement uncertainty of the certified/assigned reference values was calculated according to the ISO/BIPM guide using the specialised software GUM Workbench.

     

A critical comparison of on-line coupling IC-ICP-(AES, MS) with competing analytical methods for ultra trace analysis of microelectronic materials

On-line coupling of ion chromatography and atomic spectrometry (IC-ICP-(AES, MS)) are compared to so-called reference methods and other competing methods for ultra trace characterization of solid microelectronic materials. The comparison is based on analytical data gained for well characterized samples by a number of different laboratories. The matrices used for comparison are Mo, Mo-oxide, MoSi_x, W, W-oxide, WSi_x, metallic As, red P and Re. The analyte elements accessible by IC-ICP-(AES, MS) and with reference values for at least one other method are Ag, Al, Ba, Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Ti, Tl, Th, U and Zn. The agreement of results of IC-ICP-(AES, MS) with those of isotope dilution mass spectrometry (IDMS) and radiochemical activation analyses (RNAA) shows good accuracy for most elements and some contamination problems with ubiquitous elements. A correlation of IC-ICP-(AES, MS) and GDMS results is undoubtful, but the discrepancies are rather high. As further technique ETV-ICP-MS is compared, whose results are in reasonable agreement with IC-ICP-(AES, MS). Details on some new applications as well as of some new methodological enhancements of on-line coupling IC-ICP(AES, MS) for the matrices As and P were included. Received: 8 December 1998 / Revised: 23 March 1999 / Accepted: 28 March 1999     

Kathodenstrahlpolarographische Bestimmung von Spurenelementen in Tetrachlorogolds?ure nach ionenaustausch-chromatographischer Trennung

Zusammenfassung Die kathodenstrahlpolarographische Bestimmung von Ni, Pb, Cu, Co, Fe, Mo, Te, Sn, Zn, Bi, Cd, Tl in Tetrachlorogoldsäure wird beschrieben. Die Nachweisgrenzen liegen im 10^–4%- bzw. 10^–5%-Bereich (Ni, Co, Mo). Die Spuren werden über einen Ionenaustauscher AG 1X8 untereinander und von der Matrix getrennt.

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Cathode-ray polarographic determination of trace elements in tetrachloroauric acid after separation by ion exchange

A method is described for the cathode-ray polarographic determination of traces of Ni, Pb, Cu, Co, Fe, Mo, Te, Sn, Zn, Bi, Cd, Tl in H(AuCl₄). Gold is separated from the trace metals by absorption on the strongly basic anion-exchange resin AG 1X8. The detection limits are within the ranges of 10^–4% and 10^–5% ((Ni, Co, Mo).

     

Preconcentration of trace elements by partial dissolution of the matrix—multielement preconcentration from manganese

Trace elements such as Ag, Au, Bi, Cd, Co, Cu, Fe, Ga, In, Ni, Pb, Pd and Tl, can be preconcentrated with recoveries of better than 95% from high-purity manganese if the sample is coated with a thin layer of mercury before its dissolution in HCl to a small residue. For determination of the trace elements, the residue is completely dissolved in aqua regia. After separation of the mercury by reductive precipitation, Bi, Cd, Co, Cu, Fe, Ga, In, Ni, Pb, and Tl are determined by flame a.a.s. ('injection method'). Ag, Au and Pd are determined in the mercury-containing solution. The relative standard deviation was usually about 5%; Cu, Fe and Pb were proved to be inhomogeneously distributed in the sample (electrolytically produced manganese), and so the standard deviations were considerably greater. The detection limits for the different elements were between 0.6 and 0.004 ppm, depending on the sensitivity of their a.a.s. determination. The theoretical basis of this preconcentration method and its applicability to multielement analysis of different high-purity metals are discussed.     

Determination of heavy metal complexes with humic substances by HPLC/ICP-MS coupling using on-line isotope dilution technique

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. Received: 21 February 1997 / Revised: 27 May 1997 / Accepted: 28 May 1997     

Analytical investigations of tree rings by laser ablation ICP-MS

Laser sampling inductively coupled plasma mass spectrometry has been used for the quantitative determination of trace elements to characterize annual growth rings of trees. The elements studied are Mg, Al, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd, Ba, Tl, Pb, Bi and U. Cellulose mixed with multielement standard solution pressed into pellets were used for the calibration. Using internal standardization with ¹²C the precision is typically better than 10% relative standard deviation. The limits of detection were limited by the purity of the cellulose. Analytical figures of merit and the analytical results are discussed in terms of environmental analysis.     

Evaluation of the combined measurement uncertainty in isotope dilution by MC-ICP-MS

The combination of metrological weighing, the measurement of isotope amount ratios by a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) and the use of high-purity reference materials are the cornerstones to achieve improved results for the amount content of lead in wine by the reversed isotope dilution technique. Isotope dilution mass spectrometry (IDMS) and reversed IDMS have the potential to be a so-called primary method, with which close comparability and well-stated combined measurement uncertainties can be obtained.This work describes the detailed uncertainty budget determination using the ISO-GUM approach. The traces of lead in wine were separated from the matrix by ion exchange chromatography after HNO(3)/H(2)O(2) microwave digestion. The thallium isotope amount ratio ( n((205)Tl)/ n((203)Tl)) was used to correct for mass discrimination using an exponential model approach. The corrected lead isotope amount ratio n((206)Pb)/ n((208)Pb) for the isotopic standard SRM 981 measured in our laboratory was compared with ratio values considered to be the least uncertain. The result has been compared in a so-called pilot study "lead in wine" organised by the CCQM (Comité Consultatif pour la Quantité de Matière, BIPM, Paris; the highest measurement authority for analytical chemical measurements).The result for the lead amount content k(Pb) and the corresponding expanded uncertainty U given by our laboratory was:k(Pb)=1.329 x 10-10mol g-1 (amount content of lead in wine)U[k(Pb)]=1.0 x 10-12mol g-1 (expanded uncertainty U=kxuc, k=2)The uncertainty of the main influence parameter of the combined measurement uncertainty was determined to be the isotope amount ratio R(206,B) of the blend between the enriched spike and the sample.     

Schwermetall-Spurenbestimmung mit einem kompakten Thermionen-Quadrupol-Massenspektrometer

Zusammenfassung Es wird ein Verfahren beschrieben, welches eine Spurenbestimmung der Schwermetalle Pb, Cd, Tl, Cu und Zn durch massenspektrometrische Isotopenverdünnungsanalyse bei Verwendung eines kompakten Thermionen-Quadrupolgerätes erlaubt. Mit dieser Methode werden sehr verschiedenartige Probenmaterialien, wie Klärschlämme, Böden, Sediment, Phosphaterz und Müllasche analysiert. Die angewandten Aufschlußverfahren ermöglichen grundsätzlich eine Unterscheidung zwischen dem Totalgehalt der Schwermetalle sowie dem in Königswasser löslichen Anteil. Als Isolierungsmethoden werden alternativ eine elektrolytische Abscheidung und eine ionenaustausch-chromatographische Abtrennung diskutiert. Dabei ermöglicht eine gemeinsame Elektrodeposition der Elemente Pb, Cd, Tl und Cu auch die entsprechende massenspektrometrische Oligoelementbestimmung. Diese ist auf Proben mit nicht zu extremen Schwermetallgehalten anwendbar. Dagegen kann die Methode bei chromatographischer Abtrennung der Elemente ohne Einschränkung eingesetzt werden. Soweit Standard-Referenzmaterialien analysiert werden, stimmen die Ergebnisse mit den zertifizierten Werten überein. Vergleiche mit den massenspektrometrischen Ergebnissen bei Verwendung eines Magnetgerätes zeigen innerhalb der Fehlergrenzen identische Werte, so daß mit dem kompakten und einfach handhabbaren Quadrupolgerät für die definitive Methode der massenspektrometrischen Isotopenverdünnungsanalyse eine breitere Anwendung als bisher offen steht. Die Nachweisgrenzen des beschriebenen Verfahrens liegen für Pb bei 3 ng/g (Elektrolyse) bzw. 13 ng/g (Ionenaustauscher), für Cu bei 2 ng/g, für Cd und Tl bei 6 ng/g und für Zn bei 27 ng/g. Damit können alle umweltrelevanten Materialien der beschriebenen Art auf die genannten Schwermetalle hin analysiert werden.

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Heavy metal trace determination with a compact thermal ionization quadrupole mass spectrometerPart 1. Analysis of sewage sludges, soils and analogous materials

Summary An analytical method is described which allows trace determinations of the heavy metals Pb, Cd, Tl, Cu, and Zn with isotope dilution mass spectrometry using a compact thermal ionization quadrupole instrument for measuring the isotope ratios. Different materials, e.g. sewage sludges, soils, a sediment, a phosphat rock and a city waste incineration ash are analysed with this method. In principle, the total heavy metal contents as well as the portion, which is dissolved in aqua regia, can be determined by the chemical processes used for the decomposition of the samples. Alternatively, an electrolytic deposition and ion-exchange chromatography can be applied to separate heavy metals from the matrix. A mass spectrometric oligo-element determination of Pb, Cd, Tl, and Cu is possible by electrode-positing these elements. This type of determination can be applied to all samples which are not too extreme in their heavy metal contents. The chromatographic separation of the elements can be used without any restriction. So far as standard reference materials are analysed, the results determined with the described isotope dilution technique and the quadrupole mass spectrometer agree well with the certified values. A comparison of results, obtained with a magnetic sector field instrument, with the results of the quadrupole mass spectrometer shows identical values within the limits of error. Therefore, the availability of the quadrupole thermal ionization mass spectrometer, which is a cost-efficient solution and an instrument which is relatively easy to handle, establishes a stronger basis for the application of the isotope dilution technique. The detection limits for the described method are: 3 ng/g (electrolytic deposition) and 13 ng/g (chromatographic separation) for Pb, 2 ng/g for Cu, 6 ng/g for Cd and Tl, and 27 ng/g for Zn. These detection limits enable the analyses of all environmental samples of the described type with respect to the heavy metals mentioned.

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Herrn Prof. Dr. H. Hartkamp zum 60. Geburtstag gewidmet

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Dem Bundesministerium für Forschung und Technologie sowie dem Fonds der Chemischen Industrie danken wir für die finanzielle Unterstützung.     

Trace determination of Tl, Cu, Pb, Cd, and Zn in specimens of the limnic environment using isotope dilution mass spectrometry with thermal ionization

Within the framework of the German Environmental Specimen Bank program, Tl, Cu, Pb, Cd and Zn were determined in homogenized materials from the limnic environment using Isotope Dilution Mass Spectrometry (IDMS) with thermal ionization. The analytical procedures which were developed for the trace metal analysis of bioindicator and sediment samples are described in detail. Results obtained in bream, mussels (Dreissena polymorpha) and sediments of Lake Constance/Estuary of Constance in the sampling years 1981, 1985, 1988, 1990, 1992 and 1993 are discussed and compared with those of bream from the lakeland district of Born-hoeved/Lake Belau and from the River Saar as well as from reference materials.