Sample Decomposition Methods Research Articles

Mineral Composition of Rice, Carrots, and Chayote after Microwave-Assisted Decomposition using Diluted Nitric Acid

Carrots, chayote, and rice are foods widely consumed by the Brazilian population, so developing analytical methods that allow elemental characterization becomes extremely important. In this work, the sample decomposition method is proposed to prepare samples (raw and cooked) of rice, carrots, and chayote using dilute nitric acid. The samples underwent microwave-assisted acid decomposition (HNO3/H2O2) for subsequent determination by ICP OES for metals Al, Cd, Cr, Cu, Fe, and Pb and flame spectrophotometer for K and Na. Two decomposition methods were used. Method 1: 260 and 500 mg of sample, 3.5 mL of HNO3 1 mol L-1, 1.0 mL of 30% m/m H2O2 and 3.5 mL of ultrapure water. Method 2: 260 and 500 mg of sample, 5.0 mL of 1 mol L HNO3-1, 2.5 mL of 30% m/m H2O2 and 0.5 mL of ultrapure water. A factorial design (22) was also performed to know the effects of some variables on digestion efficiency. Based on the accuracy study using certified reference materials and the analysis of residual acidity and dissolved organic carbon, the condition that presented the best decomposition results was using 5 mL of HNO3 0.5 mol L-1 and 2.5 mL of 30% H2O2 for 100 mg of sample. Quantification limits ranged from 0.14 (Cr) 3.4 mg kg-1 (Pb), and the correlation coefficient was close to one in all cases. It was also observed that the cooking process increased the concentration of Al, Cd, and Cr and decreased Cu and K for all foods.

Psittaciformes mineral feed analysis method choice and optimization employing chemometric tools

BackgroundIn this work, a multivariated approach based on factorial design and principal component analysis was used to perform the optimization of sample decomposition. The method was applied for the first time to quantify several chemical elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Se and Zn) in Psittaciformes feed. The choice of the best sample decomposition method is a challenging task considering all variables involved in the process. Generally, this choice is made by using individual monovariated experiments and sometimes interaction effects between these variables as mass of the sample, acid composition, temperature, etc, are not considered. MethodsSample decomposition: 200 mg of sample was mixed with 3.5 mL of HNO3 65% and left at room temperature for 24 h, in a pre-decomposition step, heated at 150 °C for 50 minutes employing a digestion block and mixed with 1.5 mL of H2O2 in the last ten minutes of decomposition. Chemical analysis: A total of 44 samples of Psittaciformes feed digests, among extruded feed, flour and snacks), purchased at pet stores or similar stores in six states in Brazil, were analyzed by inductively coupled plasma optical emission spectrometry (ICP OES). Method accuracy was assessed using certified reference materials SRM 1567a, SRM 1573a, SRM 1577b and IMEP 19. ResultsThe limits of detection (LoD) and quantification (LoQ) ranged from 0.02 mg kg−1 to 0.07 mg kg−1 (Se) and from 1.79 mg kg−1 to 5.41 mg.kg−1 (Ca), respectively. The concentration of chemical elements in animal food ranged from <0.27 mgkg −1 (Fe) to 41.4 ± 2.9 g kg−1 (P), in flour concentrations ranged from <0.05 mg kg−1 (Mg) to 23.8 ± 4.1 g kg−1 (P) and concentrations ranged from <0.05 mg kg−1 (Mn) to 6.8 ± 0.9 g kg−1 (Ca) in snacks. ConclusionThe approach based on multivariate analysis to perform a sample decomposition was successfully applied for Psittaciformes feed. In general, the chemical elements listed on the product labels (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Se and Zn) were detected at variable contents when compared to the recommender nutritional values. Toxic elements, Cd and Pb were not detected in any of the analyzed samples. The detection and quantification of chemical elements not listed in nutritional tables and in each product label indicates that mineral addition by manufacturers is performed without considering the chemical composition of the raw materials used in the production process, which can lead to nutritional issues. Thus, a broad revision of Brazilian Legislation concerning product classification considering quality and mineral addition criteria in daily animal feed, especially pets, is urgently required.

Sample preparation for geochemical analysis: Strategies and significance

Accurate determination of elemental and isotopic compositions of geological samples must be a pre-requisite for successful mineral exploration, basic geochemical and geochronological studies. During rock analysis, sample digestion which involves steps from simple dilution to partial or total digestions, is a crucial step and is the limiting factor many times for achieving reproducible and accurate analytical results. Sample preparation is a critical step in the geochemical analysis, and complete sample dissolution is a pre-requisite for obtaining accurate and precise data for geological materials in most studies. Sample matrix, analytes of interest, the analytical technique, and intended purpose play a major role in selecting the optimum sample preparation method. This review focuses on the recent advances, developments, and trends in sample digestion methods, such as open-vessel acid digestion, closed digestions, microwave digestion, alkali fusion, use of NH4F for both open and closed digestions, sintering with Na2O2, fire-assay methods, infrared radiation digestions, high-pressure asher digestions, and automated sample preparation systems (based on artificial intelligence) along with examples of some important and exciting applications in geochemical and geochronological studies. Various sample decomposition methods have been compared to bring out advantages and limitations for a particular application.

Radiochemical separation of 231Pa from siliceous cake prior to its determination by gamma ray spectrometry

Abstract A simple and fast radiochemical method for the separation of protactinium (231Pa) from siliceous cake for its determination by gamma ray spectrometry is described. The method involves (a) a novel approach, the fusion of the siliceous cake with sodium peroxide, (b) the dissolution of the fused mass in nitric acid and (c) the co-precipitation of 231Pa with manganese dioxide formed in-situ by the addition of solid manganous sulfate and potassium permanganate to the solution. The fusion, effected in a single step, is simpler and highly effective in comparison to methods reported hitherto in literature. The radiochemical yield of 231Pa, determined using 311.9 keV gamma ray of 233Pa radiotracer is quantitative (~90%). The decontamination factors calculated using gamma ray spectrometry and energy dispersive X-ray fluorescence measurements show that the separation from the interfering radionuclides is high whereas separation from major and minor elements is good. Separation by ion-exchange method in hydrochloric acid, hydrofluoric acid and oxalic acid media have comparatively much lower yields. The concentration of 231Pa in the siliceous cake measured using interference-free 283.6 keV gamma ray was found to be (6.4±0.33) μg kg−1. The measured concentration of 231Pa was well above the limit of quantitation whereas the coefficient of variation was ~5%. The improvement in the limit of detection was due to the reduction in spectral background. Systematic evaluation of various uncertainty parameters showed that the major contributors to the combined uncertainty were efficiency of the high purity germanium detector and the counting statistics. The present sample decomposition and separation methods are robust, simple to perform and can be effectively used for the determination and hence source prospecting of protactinium.

Decomposition of diverse solid inorganic matrices with molten ammonium bifluoride salt for constituent elemental analysis

Ammonium bifluoride (ABF, NH4F·HF) is a well-known reagent for converting metal oxides to fluorides and for its applications in breaking down minerals and ores in order to extract useful components. It has been more recently applied to the decomposition of inorganic matrices prior to elemental analysis. Herein, a sample decomposition method that employs molten ABF sample treatment in the initial step is systematically evaluated across a range of inorganic sample types: glass, quartz, zircon, soil, and pitchblende ore. Method performance is evaluated across two variables: duration of molten ABF treatment and ABF reagent mass to sample mass ratio. The degree of solubilization of these sample classes are compared to the fluoride stoichiometry that is theoretically necessary to enact complete fluorination of the sample types. Finally, the sample decomposition method is performed on several soil and pitchblende ore standard reference materials, after which elemental constituent analysis is performed by ICP-OES and ICP-MS. Elemental recoveries are compared to the certified values; results indicate generally good to excellent recoveries across a range of alkaline earth, rare earth, transition metal, and actinide elements.

火焰原子吸收光谱法测定锰铁炉渣中微、痕量钴

通过对锰铁炉渣的化学组成和性质的研究，确定了以火焰原子吸收光谱法测定钴的实验方法。通过研究，找出了样品分解方法、最佳测定介质和酸度、共存离子的干扰情况等。样品分解过程中加入氢氟酸与二氧化硅生成四氟化硅，经高氯酸冒烟除去，即可达到完全分解，同时消除硅的干扰。锰、钙、镁、铝等含量较高的基体对钴的测定没有干扰。实验表明，方法的检出限为0.0078 mg/L，相对标准偏差处于0.34%~2.14%之间，回收率在97.8%~101.4%范围内，满足分析要求。该方法已成功应用于锰铁炉渣中钴的分析，并正在申报行业标准。 Through the research of the chemical composition and nature of ferromanganese slag, the method of cobalt by the flame atomic absorption spectrometry was determined. Through the research, we found out the sample decomposition method, the best optimal medium and acidity, the interference of coexisting ions, etc. In the process of decomposition, sample was decomposed completely by adding hydrofluoric acid to reaction with silicon to generate SiF4 which was removed by perchloric acid smoking, so the interference of silicon on the determination of cobalt was eliminated completely. Calcium, magnesium and aluminum didn’t affect the determination of cobalt. Experi-mental results showed that the detection limit was 0.0078 mg/L, the relative standard deviation was between 0.34%~2.14%, the recovery rate was in the range of 97.8%~101.4%, and the analysis results was good. Successfully, the method has been applied in the analysis of cobalt in ferro-manganese slag, and is to declare the industry standard.

Determination of Tellurium in Tellurium-Containing Organic Compounds by Microwave Plasma-Atomic Emission Spectrometry

A method for determining tellurium in tellurium-containing organic compounds (TOC) by a microwave plasmaatomic emission spectrometer Agilent 4100 has been suggested. One of the sample decomposition methods - the oxygen flask combustion or the acid decomposition in a heating block-can be applied. Telluradiazole derivatives and some other TOC with 20 to 58% tellurium content have been analyzed. Elements such as nitrogen, sulfur, potassium, selenium present in the TOC do not prevent from determining tellurium. The relative error of the analysis is 1-5%. Telluradiazole derivatives and some other tellurium-containing organic compounds with 20 to 58% tellurium content have been analysed by MP-AES spectrometer Agilent 4100

Getting Information from Modal Decomposition of Grain Size Distribution Curves

Abstract Soil samples may be difficult-to-identify mixtures of different layers. For environmental and groundwater projects, a detailed stratigraphy is needed because the coarse layers are highways for both water and dissolved contaminants. The paper proposes a method to decompose a grain size distribution curve (GSDC) into its 1, 2, or 3 log-normal components and their proportions. The proposed method can accurately decompose synthetic mixes of three lognormal modes, except when a mode contributes for less than about 2 %. In such a case, it is suggested to ignore this mode and describe the mix as a two mode mix. An example is given for an experimental site with many split-spoon soil samples. The suspected stratification was confirmed by the decomposition method, which found mixtures of only two soil components, fine sand and clayey silt, each of them with little variability. The large-scale permeability, as provided by a pumping test, corresponds to the horizontally composed permeability of the soil components: thus, it confirms the adequacy of the soil sample decomposition method.

Rapid bulk rock decomposition by ammonium fluoride (NH4F) in open vessels at an elevated digestion temperature

Complete dissolution is essential for achieving accurate analytical results for geological samples. Hydrofluoric acid is the most effective mineral acid for breaking up strong Si–O bonds to form SiF6−2 ions in acidic solution. However, HF is rather inefficient in the open-vessel acid digestion of refractory minerals such as zircon due to its low boiling point (boiling point of 38.3% HF=112°C). In this study, a decomposition technique using the solid compound NH4F in an open vessel (Savillex Teflon vial) has been investigated for the multi-element analysis of various rock reference materials. The higher boiling point (260°C) of NH4F allows for an elevated digestion temperature in open vessels, which enables the decomposition of refractory phases. Using this method, Zr was completely recovered from the granodiorite GSP-2 reference material in 1–1.5h at 250°C, which is ~12 times faster than using conventional closed-vessel acid digestion at 190°C (high-pressure PTFE digestion bomb). There is a positive correlation between the test sample mass and the amount of NH4F required for complete recovery of Zr, Hf, Nb, Ta, and heavy rare earth elements in GSP-2, which is due to the resistance of zircon (which is a major reservoir for heavy rare earth elements) to decomposition at lower reagent to sample ratios. The recommended proportion of NH4F, relative to the amount of sample powder required for complete element recovery, is 6:1. Unlike in NH4F-assisted high-pressure acid digestion, our results clearly indicate that adding HNO3 severely inhibited the digestion capabilities of NH4F for refractory minerals such as zircon in open vessels. The most outstanding advantage of the new method is that the digestion can be performed in a conventional Savillex Teflon vial instead of a high-pressure PTFE digestion bomb. Moreover, NH4F−open-vessel acid digestion is not hampered by the formation of insoluble fluorides, which represents another important advantage of this new sample decomposition method. Similar to HF and HNO3, ultra-pure NH4F can be produced using a conventional PFA sub-boiling purification system, and it does not induce new interference species in ICP-MS analysis. Additionally, this reagent is removed by taking the sample to dryness, which is important to keep the total dissolved solid of the final solution presented to the instrument low. NH4F has many of the same safety handling requirements of HF, especially when being heated to dryness to remove the Si as SiF4, and excess reagent as HF, so safety issues are still a concern. The developed NH4F−open-vessel acid digestion method has been successfully applied to the digestion of a series of international geological reference materials. This simple, effective, and comparatively safe dissolution method shows great potential for the digestion of geological samples.

The combination of infrared and microwave radiation to quantify trace elements in organic samples by ICP OES

Sample-decomposition methods using microwave radiation in closed systems have been commonly used in the analysis of inorganic constituents; however, these methods are limited to small amounts of organic samples. This work proposes the combined use of infrared radiation and microwave radiation (IR-MW) to increase the amount of organic samples digested. The determination of Al, Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn in human-feed samples was accomplished by ICP OES. The results were in agreement with those obtained from conventional decomposition by microwave radiation (closed system). The results obtained using the proposed IR-MW system for standard reference material (whole milk powder, NIST 8435) were also compared. Agreements of 85–100% were obtained for Al, Ca, Cu, Fe, K, Mg, Na, P and Zn in the standard reference material. The IR-MW system is simple to implement and cheap because it uses commercially available infrared lamps and allows the use of infrared radiation in the microwave-digestion vessel. Additionally, it is possible to reach better precision in the analysis of the human-feed samples using the IR-MW system. The proposed method also allows total digestion of large sample amounts or samples rich in organic compounds can also be performed in the IR-MW system using small volumes of nitric acid.

Comparative study of sample decomposition methods for the determination of total Hg in crude oil and related products

This paper presents a comparative study of three decomposition methods (A, B and C) for the determination of total Hg (THg) in crude oil and related products by cold vapor atomic absorption spectrometry (CV-AAS). Methods A and B employed closed-pressurized (HPA-S) and cold-finger systems, respectively. Method C employed a pyrolysis system. Some procedures were introduced to improve the weighing of samples in quartz boats, as well as for the cleaning of the boats, after sample pyrolysis. Also, the weighing of samples and their transfer into the cold-finger vessels, which were too long and heavy, were facilitated. Furthermore, the digestion time of the sample in the HPA-S was optimized. Spiked certified reference materials and one spiked crude oil sample were used for accuracy tests. Satisfactory recoveries (75–123%), repeatability and reproducibility (RSD≤14%) for the THg results were obtained for all tested methods. Also, the THg concentrations in crude oil and oil sludge samples obtained by all tested methods were statistically similar. Although method B is commercially available in a low cost and can simultaneously pre-treat many samples, it showed the highest blank concentration, the highest LOQ, the longest digestion time and a high burst risk.

Arsenic and antimony determination in refined and unrefined table salts by means of hydride generation atomic absorption spectrometry--comparison of sample decomposition and determination methods

An evaluation was made of different digestion methods for the determination of arsenic and antimony in table salt samples prior to hydride generation atomic absorption spectrometric analysis. Microwave acid digestion, classical wet digestion, dry ashing, and fusion were applied to the decomposition of salt samples and optimum conditions were investigated. Samples were decomposed by changing heating time, digestion techniques, and the amount and composition of acid, and then the concentrations of arsenic and antimony in an unrefined salt sample were measured. It is concluded that microwave acid digestion decomposes salt samples with a very short heating time and with small amounts of reagents compared with the classical wet digestion methods, which require several hours for the heating step and several milliliters of reagents. The accuracy of the procedure was checked using pond sediment certified reference material. The proposed procedure was applied for the determination of arsenic and antimony in several table salt samples collected in ›zmir, Turkey, and the arsenic contents in the samples were found to be below the maximum permissible limits. Microwave digestion in combination with hydride generation atomic absorption spectrometry could be used routinely to monitor these metals in table salt samples.

Carbon-14 analysis in solidified product of non-metallic solid waste by a combination of alkaline fusion and gaseous CO2 trapping

In order to establish a simple and rapid analytical method for (14)C in solidified products made from non-metallic low-level radioactive solid wastes such as concrete, mortar and glass by melting treatment, a radiochemical analysis in combination with alkaline fusion as a sample decomposition method was examined. A simulated solidified product containing (14)C, which was prepared by using nuclear reaction (14)N(n, p)(14)C with thermal neutron irradiation, was analyzed by the present method to compare with a conventional radiochemical analysis using oxidizing combustion. The reproducible and quantitative recovery of (14)C from the simulated solidified product indicates that the present method is more efficient for (14)C analysis in solidified products than the conventional method using oxidizing combustion.

Novel fusion method for direct determination of uranium in ilmenite, rutile, columbite, tantalite, and xenotime minerals by laser induced fluorimetry

A simple, rapid, effective and eco-friendly decomposition method is developed for the determination of uranium (U) by laser induced fluorimetry (LIF). The salts of sodium di-hydrogen phosphate (NaH2PO4) and di-sodium hydrogen phosphate (Na2HPO4) were used in the ratio of 1:1 (phosphate flux) for the decomposition and dissolution of refractory, non silicate minerals like ilmenite, rutile, columbite, tantalite, and xenotime. The effect of associated matrix elements (Ti, Fe, Nb, Ta, Mn and Y present in the sample) on quenching of uranyl fluorescence was studied. The flux used for the sample decomposition has several advantages. In the reported sample decomposition methods, α-hydroxy acids are used as complexing agents to prevent hydrolysis and to get clear and stable solution. This solution can not be directly used for U determination by LIF as α-hydroxy acids quench uranyl fluorescence, hence separation is required. In the present method no such separation is required. The flux itself acts as fluorescence enhancing reagent and buffer (maintaining the optimum pH of 7.1 ± 0.1). The fused melt of the flux mixture, when disintegrated in water, gives clear and stable solution and has high tolerance for most of inorganic quenchers compared to reported phosphate buffers. Also just by dilution (due to high sensitivity of LIF), the concentration of quenchers could be brought down well within the tolerance limit. The accuracy and precision of the method was evaluated by analyzing Certified Reference Materials (IGS-33 and IGS-34 of Institute of Geological Sciences, UK) and Synthetic Minerals. The accuracy of the data is further evaluated by comparing with standard decomposition methods. The results are well within the experimental error. The RSD of the method is ±10% (n = 6) at 10 ppm level for Ilmenite and for other minerals the RSD of the method is ±5% (n = 6) at 50 ppm level. The method is being routinely applied to various refractory samples received from Rare Metal and Rare Earth Investigations for determination of uranium by laser fluorimetry.

Some Observations on the Determination of Gold and the Platinum‐Group Elements in Black Shales

This research compares various ways of applying oxidative chemical decomposition to the analysis of gold‐bearing black shale ores from the Russian Natalka and Sukhoj Log deposits. This study was conducted as part of the certification program for the Russian candidate black shale reference materials SLG‐1 and SCHS‐1 and also because of the paucity of data available on the determination of the platinum group elements (PGE) in analogous sample types. We report direct evidence of PGE volatilisation from black shale materials when processed in the presence of oxygen. We also developed a comprehensive analytical scheme for the quantitative determination of PGE in all phases (gaseous and ash) produced during slow combustion of carbonaceous materials in oxygen.This study has shown that during combustion in oxygen at 600 °C, PGE contained in the Natalka black shale ores are lost as gaseous reaction products. Thus, the volatilized PGE (recovered in traps) account for up to 14% Pt, 40% Pd, 40% Ru and 10 % Ir relative to their total concentrations in a carbonaceous concentrate. It was also established that in the process of combustion, Au quantitatively remains in the ash cake.In order to avoid the deleterious effects of oxygen on the volatility of the PGE, we propose a new comprehensive sample decomposition method based on the application of fluoroxidants such as BrF3and KBrF4. This method was validated using samples of black shale ores and their processing products by comparing our results with those obtained independently using sealed autoclave processing of the same materials. It was shown that PGE in black shale ores and their processing products not only exist in commercially exploitable quantities but that a small proportion of PGE compounds are soluble in alcohol. We propose that in gold‐bearing black shale ores, PGE are present as organometallic compounds.

Development of a microwave sample preparation method for the determination of arsenic in humus and moss samples by graphite furnace atomic absorption spectrometry

Two sample decomposition methods were optimized for the determination of arsenic by graphite furnace atomic absorption spectrometry (GFAAS) in moss and humus samples. In the first method, 5,0 ml of HNO 3 and 3,0 ml of H 2 O 2 were used for the decomposition of 500 mg of sample. When humus samples were decomposed in this way a slight, undissolved residue remained. Therefore, another sample decomposition method, including hydrofluoric acid, was also tested (5,0 ml HNO 3 ; 3,0 ml H 2 O 2 ; 0,4 ml HF; 2,5 ml H 3 BO 3 ). Pyrolytically coated graphite tubes, equipped with integrated or L'vov platfoms, were used in the determination of arsenic by GFAAS. Palladium-magnesium nitrate was used as a matrix modifier. Several reference materials (e.g. humus, moss, lichen, sea lettuce) were analyzed.

Determination of analytical limits in solid sampling ETAAS: a new approach towards the characterization of analytical quality in rapid methods.

In the present study the lower analytical limits of solid sampling electrothermal atomization atomic absorption spectrometry (SS-ETAAS) were characterized by means of blank measurements and--for the first time--by means of the calibration curve method, where a calibration near the range of these limits (limit of decision, detection and quantification) was performed. The limit of decision as derived from blank measurements was calculated according to the 3sigma-criterion to be 0.003 and 0.019 ng for Cd and Pb, respectively. For Pb and Cd a roughly three-fold increase of these limits was observed when the calibration method according to DIN 32 645 was applied. When solid reference material was used, only a slight increase could be observed. The analytical limits were 2 to 20 times lower than reported for sample decomposition methods. The blank measurement and conventional calibration curve method, however, do not account for factors relating to solid sampling such as sample mass and matrix. Therefore, the calibration curve model was applied to data derived from comparisons between direct solid sampling ETAAS and a compound reference method (ETAAS following sample homogenization and digestion). The observed analytical limits were not found to be substantially increased if enough samples with low element contents were available for calibration. Coupling of the calibration curve model with the comparison of methods included real test samples and thus the relevant maximum sample mass and analyte content in the range of the lower analytical limits. As validation procedures frequently include comparisons of methods, the present approach might prove to be of some general interest for the characterization of analytical quality in rapid methods.

Determination of total tin in sediment reference materials by isotope dilution inductively coupled plasma mass spectrometry after alkali fusion

The total tin concentration in a candidate sediment reference material (NIES CRM No.12 Marine Sediment) was determined by inductively coupled plasma mass spectrometry (ICP-MS) with a combination of different sample decomposition methods (acid digestion and alkali fusion) and modes of quantification [standard addition and isotope dilution (ID)] during a collaborative analysis for certification. Good agreement between the methods was obtained (10.2–11.0 mg kg–1) and the data were consistent with those obtained from collaboration laboratories (9.38–11.6 mg kg–1). Among the analytical methods used in this study, the most precise method, ID-ICP-MS, was examined further for its accuracy by analyzing other sediment CRMs. The analytical values obtained after acid digestion and alkali fusion differed significantly for all seven sediment CRMs analyzed; the total tin value was consistently higher and the relative standard deviation of the analysis was larger when the sample was decomposed by alkali fusion than by acid digestion. The difference varied from CRM to CRM (3–80%). This result indicated that there was a fraction of tin that was resistant to acid attack and the distribution of the fraction in the sediment was inhomogeneous. For an accurate determination of total tin in sediment, alkali fusion-ID-ICP-MS is the most suitable method.

Iodine determination in biological materials

This paper describes the development of various new acid sample decomposition methods, as well as an extraction (leaching) method and compares them with the “Schoniger Combustion” technique. The methods have been developed as sample preparation techniques for iodine determination in biological materials, especially in solid samples. ICP-MS (inductively coupled plasma mass spectrometry) and a catalytic technique are employed and discussed for the final determination of iodine concentrations. Accuracy and reliability of the different analytical methods are shown in the examples of different CRMs (certified reference materials) available for iodine. The results of an interlaboratory comparison are specifically presented for the extraction (leaching) method.

Application of procedures for low level radionuclide analysis in environmental monitoring for the purpose of clearance measurements of materials from decommissioning of nuclear facilities

Materials from decommissioning of nuclear facilities can be re-used without restrictions, if their mass specific activities are in accordance to the guidelines for allowable concentrations. To determine the nuclide specific activity level of representative samples, a “clearance laboratory” was installed at the Research Center Karlsruhe. For the purpose of low level radionuclide analysis, procedures, developed for environmental monitoring, were successfully adapted to decommissioning materials. For radionuclides, for which adequate procedures were not available, new methods were developed. The procedures for the analysis of radionuclides of prior interest for decommissioning measures are outlined, together with the respective sample decomposition methods.