Iodspurenbestimmung mit der negativen Thermionen-Massenspektrometrie: Analyse von Speisesalzen sowie Vergleich mit Ergebnissen einer ionenselektiven Elektrode

Zusammenfassung Bei Erzeugung negativer Thermionen im Massenspektrometer wird eine Meßtechnik zur genauen Isotopenverhältnisbestimmung ¹²⁹I/¹²⁷I entwickelt. Die Anwendung der Isotopenverdünnungsanalyse unter Verwendung eines Indicators, der an dem langlebigen radioaktiven ¹²⁹I-Isotop angereichert ist, ermöglicht in diesem Zusammenhang auch eine vergleichsweise richtige Iodspurenbestimmung mit dem Massenspektrometer. In verschiedenen, handelsüblichen Speisesalzen sowie in zwei Reinchemikalien werden Iodspuren mit der massenspektrometrischen Isotopenverdünnungsanalyse bestimmt, wobei relative Standardabweichungen von etwa 1,5 % im unteren ppm-Bereich erreicht werden. Die Nachweisgrenze des beschriebenen Verfahrens, welches die Summe aller anorganischen Iodspecies erfaßt, liegt bei 6 ppb. Die zum analytischen Vergleich durchgeführten Bestimmungen mit einer iodidselektiven Elektrode zeigen gute Übereinstimmung der Ergebnisse. Die chemische Abtrennung des Iodidions geschieht mit der Anionenaustausch-Chromatographie.

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Iodine trace determination by negative thermal ionization mass spectrometry: Analysis of table salts and comparison with results by an ion-selective electrode

Summary A technique for a precise isotope ratio measurement of ¹²⁹I/¹²⁷I is developed in the mass spectrometer by negative thermal ionization. The application of the isotope dilution technique using a spike which is enriched in the longlived radioactive ¹²⁹I isotope opens the possibility for an accurate iodine trace analysis by mass spectrometry. Different commercially available table salts as well as two pure chemicals are determined for iodine traces by mass spectrometric isotope dilution analysis. Relative standard deviations of about 1.5 % are obtained in the lower ppmrange. The detection limit of this method which analyses the sum of all inorganic species is 6 ppb. For an analytical comparison the same samples are analysed using an iodideselective electrode. The results agree well with the mass spectrometric values. The chemical separation of the iodide ion is carried out by anion-exchange chromatography.

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

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Der Deutschen Forschungsgemeinschaft sowie dem Fonds der Chemischen Industrie danken wir für die finanzielle Unterstützung.     

Iodine-129 in Thyroid Glands: A Sensitive Biological Marker of Fission Product Exposure

Iodine-129 may have no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioiodine contamination. Since 1943, ¹²⁹I/¹²⁷I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer living near a nuclear reprocessing facility have contained ¹²⁹I, which are 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of ¹²⁹I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that ¹²⁹I, may be helpful to evaluate past radiation hazard from fission products.     

High-Precision Measurements of the 143Nd/144Nd Isotope Ratio in Certified Reference Materials without Nd and Sm Separation by Multiple Collector Inductively Coupled Plasma Mass Spectrometry

We present a precise and accurate method for the determination of ¹⁴³Nd/¹⁴⁴Nd isotope ratio without Nd and Sm separation by multiple collector inductively coupled plasma mass spectrometry. We corrected instrumental mass discrimination by applying the natural constant ¹⁴⁶Nd/¹⁴⁴Nd ratio as an internal standard after isobaric interference correction of ¹⁴⁴Sm on ¹⁴⁴Nd using interference-free ¹⁴⁷Sm/¹⁴⁹Sm ratio for Sm mass fractionation. The present method was validated by duplicate analyses of several certified reference materials after dissolution and cation-exchange resin purification. The precision (2σ) of the ¹⁴³Nd/¹⁴⁴Nd ratio is less than 10 ppm (internal) and 20 ppm (external), respectively.     

Determination of129I in soils of Germany using radiochemical neutron activation analysis

At 5 sampling sites distributed throughout Germany the¹²⁹I concentrations in soils have been measured in individual depth intervals to a depth of 60 cm. These measurements are used to determine the total amount of¹²⁹I in a soil column of 60 cm depth. The data indicate that the¹²⁹I concentrations and the¹²⁹I/¹²⁷I isotope ratios are higher at the sampling locations near the coast compared to the sampling locations in Southern Germany. The total¹²⁹I inventories in the top 60 cm of soils are correlated with the¹²⁹I deposition through rainfall.     

Oxygen isotope analysis of phosphate: improved precision using TC/EA CF‐IRMS

Oxygen isotope values of biogenic apatite have long demonstrated considerable promise for paleothermometry potential because of the abundance of material in the fossil record and greater resistance of apatite to diagenesis compared to carbonate. Unfortunately, this promise has not been fully realized because of relatively poor precision of isotopic measurements, and exceedingly small size of some substrates for analysis. Building on previous work, we demonstrate that it is possible to improve precision of δ¹⁸O_PO4 measurements using a ‘reverse‐plumbed’ thermal conversion elemental analyzer (TC/EA) coupled to a continuous flow isotope ratio mass spectrometer (CF‐IRMS) via a helium stream [Correction made here after initial online publication]. This modification to the flow of helium through the TC/EA, and careful location of the packing of glassy carbon fragments relative to the hot spot in the reactor, leads to narrower, more symmetrically distributed CO elution peaks with diminished tailing. In addition, we describe our apatite purification chemistry that uses nitric acid and cation exchange resin. Purification chemistry is optimized for processing small samples, minimizing isotopic fractionation of PO₄^?3 and permitting Ca, Sr and Nd to be eluted and purified further for the measurement of δ⁴⁴Ca and ⁸⁷Sr/⁸⁶Sr in modern biogenic apatite and ¹⁴³Nd/¹⁴⁴Nd in fossil apatite. Our methodology yields an external precision of ± 0.15‰ (1σ) for δ¹⁸O_PO4. The uncertainty is related to the preparation of the Ag₃PO₄ salt, conversion to CO gas in a reversed‐plumbed TC/EA, analysis of oxygen isotopes using a CF‐IRMS, and uncertainty in constructing calibration lines that convert raw δ¹⁸O data to the VSMOW scale. Matrix matching of samples and standards for the purpose of calibration to the VSMOW scale was determined to be unnecessary. Our method requires only slightly modified equipment that is widely available. This fact, and the demonstrated improvement in precision, should help to make apatite paleothermometry far more accessible to paleoclimate researchers. Copyright © 2009 John Wiley & Sons, Ltd.     

Precise thermal ionization mass spectrometric measurements of 142Nd/144Nd and 143Nd/144Nd isotopic ratios of Nd separated from geological standards by chromatographic methods

A chromatographic separation technique for ¹⁴²Nd/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd isotope ratio measurements is established and applied to the analyses of geological standards of basaltic compositions (BCR-2, BIR-1) using Isoprobe-T TIMS. The instrument was tested for reliability and reproducibility to measure Nd isotope composition using the synthetic standard JNdi-1. The techniques were also applied to a carbonatite lava sample, OL-6, Oldoinyo Lengai, to check the validity of method for carbonatite matrix. The isotope ratios of ¹⁴³Nd/¹⁴⁴Nd for synthetic Nd standard JNdi-1, geological standards BCR-2, BIR-1, and carbonatite lava sample OL-6 obtained by these methods are in good agreement with previously published data. The ¹⁴³Nd/¹⁴⁴Nd values for JNdi-1 and BCR-2 have an external precision of ±13 ppm and ±15 ppm (2σ), respectively. The JNdi-1 and BCR-2 data for ¹⁴²Nd/¹⁴⁴Nd has an external precision of ±12 ppm and ±8 ppm (2σ), respectively. The ¹⁴²Nd/¹⁴⁴Nd composition of the two geological standards BCR-2 and BIR-1 are indistinguishable from synthetic mono-element standard JNdi-1, and they all fall within the 12 ppm (2σ) envelope of external precision. The external reproducibility is sufficient to distinguish and resolve 20 ppm anomalies in ¹⁴²Nd/¹⁴⁴Nd values.     

Iodine-129 in Thyroid Glands: A Sensitive Biological Marker of Fission Product Exposure

appeared in the Journal of Radioanalytical and Nuclear Chemistry, Vol. 243, No. 2 (2000) 467–472.During the electronic submission of the paper the file was damaged, and parts were left out. In order to correct this, we publish the correct paper as a whole.Iodine-129 may be no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioactive contamination. Since 1943, ¹²⁹I/¹²⁷I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer, living near a nuclear reprocessing facility have contained ¹²⁹I which is 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of ¹²⁹I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that ¹²⁹I may be helpful to evaluate past radiation hazard from fission products.     

Negative thermal ionization mass spectrometry of selenium part 3.* Selenium trace determination in food samples

Summary Selenium traces are analysed in different animal tissue samples with isotope dilution mass spectrometry using the formation of negative Se^– thermal ions (NTI-IDMS) for isotope ratio measurements. An enriched⁸²Se spike is applied for the isotope dilution technique. After decomposition of the food samples with a HNO₃/HCIO₄ mixture selenium is separated by the formation of SeH₂ using a hydride generation system which is normally applied for atomic absorption spectrometry. Selenium hydride is absorbed in a cone. HNO₃ solution, from which sample mass spectrometric determinations are carried out. The recovery of selenium for the total sample treatment has been determined with a⁷⁵Se tracer to be about 62%. The precision of the IDMS method in the concentration range of 0.1–10 g/g lies between 1.8% and 4.1 %. The IDMS results agree well with the certified values of the analysed standard reference materials. A comparison of these results with those achieved by an isotope dilution method, using the formation of piazselenol and gas-chromatographic separation (GC-IDMS), and by hydride generation atomic absorption spectrometry (HGAAS) is given. Whereas the NTI-IDMS and GC-IDMS results are in very good agreement, HGAAS can be affected by interferences.

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Negative Thermionen-Massenspektrometrie von Selen Teil 3. Selenspurenbestimmung in Lebensmittelproben

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Part 2: see [131

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Mass spectrometry of long-lived radionuclides

The capability of determining element concentrations at the trace and ultratrace level and isotope ratios is a main feature of inorganic mass spectrometry. The precise and accurate determination of isotope ratios of long-lived natural and artificial radionuclides is required, e.g. for their environmental monitoring and health control, for studying radionuclide migration, for age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, for quality assurance and determination of the burn-up of fuel material in a nuclear power plant, for reprocessing plants, nuclear material accounting and radioactive waste control. Inorganic mass spectrometry, especially inductively coupled plasma mass spectrometry (ICP-MS) as the most important inorganic mass spectrometric technique today, possesses excellent sensitivity, precision and good accuracy for isotope ratio measurements and practically no restriction with respect to the ionization potential of the element investigated—therefore, thermal ionization mass spectrometry (TIMS), which has been used as the dominant analytical technique for precise isotope ratio measurements of long-lived radionuclides for many decades, is being replaced increasingly by ICP-MS. In the last few years instrumental progress in improving figures of merit for the determination of isotope ratio measurements of long-lived radionuclides in ICP-MS has been achieved by the application of a multiple ion collector device (MC-ICP-MS) and the introduction of the collision cell interface in order to dissociate disturbing argon-based molecular ions, to reduce the kinetic energy of ions and neutralize the disturbing noble gas ions (e.g. of ¹²⁹Xe⁺ for the determination of ¹²⁹I). The review describes the state of the art and the progress of different inorganic mass spectrometric techniques such as ICP-MS, laser ablation ICP-MS vs. TIMS, glow discharge mass spectrometry, secondary ion mass spectrometry, resonance ionization mass spectrometry and accelerator mass spectrometry for the determination of long-lived radionuclides in quite different materials.     

Rapid and precise determination of Sr and Nd isotopic ratios in geological samples from the same filament loading by thermal ionization mass spectrometry employing a single-step separation scheme

Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr + REEs fractions were dissolved and loaded onto the same Re filament using 1 μL of 2 M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method.     

Verification measurements of the IRMM-1027 and the IAEA large-sized dried (LSD) spikes

In the frame of the accountancy measurements of the fissile materials, reliable determinations of the plutonium and uranium content in spent nuclear fuel are required to comply with international safeguards agreements. Large-sized dried (LSD) spikes of enriched ²³⁵U and ²³⁹Pu for isotope dilution mass spectrometry (IDMS) analysis are routinely applied in reprocessing plants for this purpose. A correct characterisation of these elements is a pre-requirement for achieving high accuracy in IDMS analyses. This paper will present the results of external verification measurements of such LSD spikes performed by the European Commission and the International Atomic Energy Agency.

     

Negative thermal ionization mass spectrometry of selenium part 4. Selenium trace determination in sediments and related samples

Summary Selenium traces have been determined in different sediments (estuarine, river, lake), sandy soil and sewage sludge with isotope dilution mass spectrometry (IDMS). Negative selenium atomic ions are formed in a double-filament thermal ion source. The use of a silica gel technique for ionization improves the mass spectrometric sensitivity by a factor of 40 compared with the technique previously applied. An enriched⁸²Se spike is used for the isotope dilution process. The samples are decomposed with a mixture of conc. HNO₃ and conc. HE After decomposition selenium is separated by the formation of SeH₂ in a hydride generation system which is normally applied for atomic absorption spectrometry. The IDMS results for three standard reference sediments agree well with the certified values. In the case of three other standard reference materials, which are not certified for selenium up to now, the IDMS analyses were able to improve the selenium data given for information or as indicative values. The precision of the IDMS method in the concentration range of 0.2–3.5 g/g lies between 0.8 % and 4.1 %. The detection limit is 6 ng/g. A comparison with several other methods shows that IDMS is one of the very few analytical methods which produces accurate selenium results even at concentration levels of 0.2 g/g and less in sediments and related samples of environmental interest.

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Negative Thermionen-Massenspektrometrie von Selen Teil 4. Selenspurenbestimmung in Sedimenten und vergleichbaren Proben

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Dedicated to Prof. Dr. G. Tblg on the occasion of his 60th birthday     

Iodine-129 in Missouri rain and milk

A combination of neutron activation and mass spectrometry was used to measure¹²⁹I and¹²⁷I in local samples of rain and milk. The general distribution of values for the¹²⁹I/¹²⁷I ratio in these samples can be understood in terms of well established geochemical and biological cycles of iodine, but the origin of high¹²⁹I/¹²⁷I ratios in a few of the samples collected in 1976 is not understood. The procedures used to extract and purify iodine were tested by monitoring¹³¹I in rain and milk following the Chinese atmospheric bomb test of September 17, 1977.     

Determination of 129I in biomonitors collected in the vicinity of a nuclear power plant by neutron activation analysis

Neutron activation analysis (NAA) was used to determine ¹²⁹I and the ¹²⁹I/¹²⁷I ratio in bovine thyroid, moss, and river sediment samples collected in the vicinity of the Temelín nuclear power plant (NPP) in south Bohemia. The NAA procedures comprised pre-irradiation separation of ¹²⁹I by combustion of the samples in the stream of oxygen at 1,000 °C and trapping the liberated iodine in a LiOH/(NH₄)₂SO₃ solution. Post-irradiation separation of ¹³⁰I produced by the reaction ¹²⁹I(n,γ)¹³⁰I was carried out by extraction of elementary iodine with chloroform followed by precipitation of PdI₂. Nondestructive, epithermal NAA was used to determine ¹²⁷I employing the ¹²⁷I(n,γ)¹²⁸I reaction. The results showed that mean values of ¹²⁹I and the ¹²⁹I/¹²⁷I ratio in the bovine thyroids varied from 22 to 61 mBq kg^?1 (dry mass) and 2.8 × 10^?9 to 5.4 × 10^?9, respectively. These values are close to the lower end of results reported from various regions non-polluted with ¹²⁹I. No significant differences were found between ¹²⁹I concentrations and the ¹²⁹I/¹²⁷I ratios in the bovine thyroids collected prior to the start and after several years of operation of the NPP. The mean value and standard deviation of ¹²⁹I in mBq kg^?1, dry mass and the ¹²⁹I/¹²⁷I ratio in moss Pleurozium schreberi were 23 ± 16 and 2.3 × 10^?9, respectively, whereas values of ¹²⁹I in the river sediments were below 8–10 mBq kg^?1 (dry mass) after several years of the NPP operation.     

Simultaneous non-destructive determination of long-lived radionuclides in contaminated seaweed by X-ray spectrometry

Summary Planar high purity germanium detectors have been used for activity determination of fission nuclides, as well as transuranic elements, in a contaminated seaweed. The activity of a given isotope was deduced from the absolute detection efficiency of the detector and from the branching ratioR=N _k /N of the K-X photons emitted by desintegration; in case of monoenergeticy emitters, these branching ratios have been calculated from nuclear data decay. These low-energy measurements require one standard sample only for simultaneous determination of several isotopes. The data obtained in this work for the¹³⁷Cs specific activity by non-destructive analysis are in good agreement with the results of an intercomparison exercise performed by the IAEA. Moreover, this method allows us to measure in this seaweed the specific activity of the previously not detected¹²⁹I nuclide, both by destructive and nondestructive analysis, and that of²⁴¹Pu which generally needs complicated radiochemical separations.

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Gleichzeitige nicht-destruktive Bestimmung langlebiger Radionuklide in verunreinigtem Seetang durch Röntgenspektrometrie

Zusammenfassung Planäre hochreine Germanium-Detektoren wurden zur Aktivitätsbestimmung von Spaltnukliden und von Transuranen in Seetang verwendet. Die Aktivität eines bestimmten Isotops wurde abgeleitet aus der absoluten Nachweisanzeige des Detektors und aus dem VerhältnisR=N _k /N der durch Desintegration freigesetzten K-X-Photonen; bei monoenergetischen Gammastrahlen wurde dieses Verhältnis aus der Abnahme der nuklearen Daten berechnet. Diese Messungen geringer Energien erfordern nur eine Standardprobe für die gleichzeitige Bestimmung verschiedener Isotoper. Die von uns durch nichtdestruktive Analyse ermittelten Werte für die spezifische Aktivität von¹³⁷Cs stimmen mit den Ergebnissen einer vergleichenden Untersuchung der IAEA gut überein. Außerdem konnten wir mit diesem Verfahren in diesem Seetang die spezifische Aktivität des bisher nicht festgestellten Nuklids¹²⁹J sowohl durch destruktive wie durch nicht-destruktive Analyse messen und ebenso die von²⁴¹Pu, wozu im allgemeinen komplizierte radiochemische Trennverfahren nötig sind.

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Presented in part at the 9th International Microchemical Symposium, Amsterdam, August 28–September 2, 1983.     

Determination of iodine-129 and iodine-127 in environmental samples collected in Japan

Analytical method for the determination of¹²⁹I and¹²⁷I in environmental samples has been developed by using radiochemical neutron activation analysis. The¹²⁹I levels in the samples such as soil (0.9–41 mBq/kg), precipitation (0.002–0.11 mBq/kg), pine needles (1.2–32 mBq/kg) and seaweed (<0.1–17 mBq/kg) collected near the nuclear facilities in Tokaimura were higher than those from the other areas in Japan. The highest¹²⁹I concentration was found in surface soil (0–5 cm), and the highest¹²⁹I/¹²⁷I ratios were found in pine needles and precipitation. The¹²⁹I/¹²⁷I ratio was higher in rice paddy soil than those in wheat field soil collected around Tokaimura, while the concentration of¹²⁹I somewhat higher in wheat field soil.     

Comparison of GC-ICP-MS and HPLC-ICP-MS for species-specific isotope dilution analysis of tributyltin in sediment after accelerated solvent extraction

This study describes a direct comparison of GC and HPLC hyphenated to ICP–MS determination of tributyltin (TBT) in sediment by species-specific isotope dilution analysis (SS-IDMS). The certified reference sediment PACS-2 (NRC, Canada) and a candidate reference sediment (P-18/HIPA-1) were extracted using an accelerated solvent extraction (ASE) procedure. For comparison of GC and LC methods an older bottle of PACS-2 was used, whilst a fresh bottle was taken for demonstration of the accuracy of the methods. The data obtained show good agreement between both methods for both the PACS-2 sediment (LC–ICP–IDMS 828±87 ng g^–1 TBT as Sn, GC–ICP–IDMS 848±39 ng g^–1 TBT as Sn) and the P-18/ HIPA-1 sediment (LC–ICP–IDMS 78.0±9.7 ng g^–1 TBT as Sn, GC–ICP–IDMS 79.2±3.8 ng g^–1 TBT as Sn). The analysis by GC–ICP–IDMS offers a greater signal-to-noise ratio and hence a superior detection limit of 0.03 pg TBT as Sn, in the sediment extracts compared to HPLC–ICP–IDMS (3 pg TBT as Sn). A comparison of the uncertainties associated with both methods indicates superior precision of the GC approach. This is related to the better reproducibility of the peak integration, which affects the isotope ratio measurements used for IDMS. The accuracy of the ASE method combined with HPLC–ICP–IDMS was demonstrated during the international interlaboratory comparison P-18 organised by the Comité Consultatif pour la Quantité de Matière (CCQM). The results obtained by GC–ICP–IDMS for a newly opened bottle of PACS-2 were 1087±77 ng g^–1 Sn for DBT and 876±51 ng g^–1 Sn for TBT (expanded uncertainties with a coverage factor of 2), which are in good agreement with the certified values of 1090±150 ng g^–1 Sn and 980±130 ng g^–1 Sn, respectively.     

Determination of129I and127I in environmental samples by neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICP-MS)

In order to assess the levels and behavior of¹²⁹I (half-life: 1.6×10⁷ y) and¹²⁷I (stable) in the environment, we have developed analytical procedures involving neutron activation analysis (NAA). Environmental samples collected around Tokaimura, Ibaraki Prefecture, Japan, have been analyzed using this method. Ranges of¹²⁹I and¹²⁷I concentrations in surface soil were 0.9–180 mBq kg^–1 and 1–60 mg kg^–1, respectively. Higher¹²⁹I concentrations were found in soil samples collected from coniferous forests, suggesting a contribution from tree canopies in the deposition of this nuclide. Most of the¹²⁹I in soil, was found to be retained in the first 10 cm. The¹²⁹I/¹²⁷I ratios in wheat fields were lower than those in rice paddy fields.A soil sample collected by IAEA from an area contaminated by the Chemobyl accident was also determined. The¹²⁹I concentration and the¹²⁹I/¹²⁷I ratio were 1.6 mBq kg^–1 and 1.7×10^–7, respectively. The¹²⁹I level in this sample was higher than the values obtained in areas far from nuclear facilities in Japan. It was suggested that the analysis of¹²⁹I in soils in the Chernobyl area may be useful in evaluating the¹³¹I levels at the time of the accident.Analyses of¹²⁹I and¹²⁷I by ICP-MS in water samples were also made. The analytical speed of this method was very high, i.e., 3 minutes for a sample. However, there is a sensitivity limitation for¹²⁹I detection due to interference from¹²⁹Xe with the¹²⁹I peak. The detection limits for¹²⁹I and¹²⁷I in water samples were about 0.5 mBq ml^–1 and 0.1 ng ml^–1, respectively.