Determination of iron in silicate rocks by substoichiometric radioisotope dilution analysis

Iron is determined in rocks by an isotope dilution method involving dissolution with hydro fluoric acid, extraction of iron(III) chloride into isopropyl methyl ketone, stripping with dilute nitric acid, and substoichiometric separation of the Fe-EDTA complex on a cation-exchange column. The precision and accuracy are 1.5% relative or better, as indicated by analyses of some U.S. Geological Survey standard rocks.     

Determination of Rb and Sr concentrations in rocks by radioisotope X-ray fluorescence analysis

A method is described for Rb and Sr concentration determinations in rocks by radioisotope X-ray fluorescence analysis. The yield/concentration ratios were established by increasing the concentrations of the examined elements in the sample and recording each spectrum. The analytical error in the 100-1,000 ppm concentration range was 2–4%, and for 50 ppm about 10%, and the detection limit was 5–10 ppm.     

Determination of lead in rocks by radiometric isotope dilution and substoichiometric extraction

A rapid procedure is described for the determination of lead in rocks by an isotope-dilution substoichiometric method. After the sample has been digested with acid in the presence of ²¹⁰Pb tracer, the lead is separated by dithizone extractions. After the lead has been back-extracted into aqueous solution, it is reacted with a substoichiometric amount of EDTA. Excess of unreacted lead is removed by extraction with dithizone in carbon tetrachloride, and the specific activity of the aqueous complex is determined by counting ²¹⁰Pb. The standard deviation of the method is less than 10 % for replicate determinations of lead in several U.S. Geological Survey standard rocks. The agreement with literature values indicates that the method is accurate.     

Advantages of a two-detector system in automated substoichiometric radioisotope dilution analysis

Automation widens the scope of substoichiometric radioisotope dilution analysis. This is because the very strict requirement of the manual method-chemical separation of exactly equal quantities of the test substance-need no longer be fulfilled: reproducibility of the determination is reached by means of automated operation and activity measurement. The theory given in this paper shows how the choice of suitable chemical reactions is widened and why the reliability and the advantages of isotope dilution analysis are secured by the use of a two-detector system.     

Determination of boron in nuclear materials by isotope dilution technique. Part I

Summary The application of the mass-spectrometric stable-isotope dilution technique for the determination of microgram and submicrogram quantities of boron in nuclear materials is described. An adequate amount of spike solution (enriched in¹⁰B) is added to the sample and the mixture is treated chemically to ensure isotopic equilibration. Boron is then separated as methyl borate by distillation from phosphoric acid and converted into sodium tetraborate suitable for isotopic analysis by surface ionization in a mass spectrometer. The results for boron content in a standard boric acid solution, reagents, ammonium diuranate, uranium dioxide, sintered pellets of UO₂ and uranyl nitrate are given. Owing to the simplicity, accuracy and high precision a possible application of the method would be its use for routine boron determinations in a natural uranium processing plant and/or as a standard method for intercomparison with other analytical methods.

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Zusammenfassung Die Anwendung der massenspektrometrischen Isotopenverdünnungsmethode auf die Borbestimmung im Bereich von Mikrogramm und darunter in Reaktormaterialien wurde beschrieben.Eine entsprechende Menge von angereichertem¹⁰B wird einer Probe zugegeben und die Mischung zur Herstellung des Isotopengleichgewichtes chemisch behandelt. Das Bor wird dann als Methylborat durch Destillation aus der phosphorsäurehaltigen Lösung abgetrennt und zum Zweck einer massenspektrometrischen Isotopenanalyse in Natriumtetraborat umgesetzt.Der Borgehalt in H₃BO₃-Standardlösungen, Reagenzien, Ammoniumdiuranat (ADU), UO₂, gesinterten UO₂-Pastillen und Uranylnitrat wird angegeben. Wegen der Einfachheit, Genauigkeit und Empfindlichkeit könnte diese Methode sowohl für die routinemäßige Borbestimmung bei der Herstellung von Brennstoffelementen mit natürlichem Uran als auch für die Standardisierung analytischer Methoden angewandt werden.

     

稳定同位素稀释技术在人体肝脏维生素A储备量检测中的应用

建立了稳定同位素稀释技术结合高效液相色谱-气相色谱/负化学电离源质谱法(HPLC-GC/NCI/MS)测定人体肝脏维生素A(VA)储备量的方法。志愿者在口服氘标记的视黄醇醋酸酯(²H₈-RAC)后,经21天的稳定期,采集血样,分离血清。血清经正己烷提取,高效液相色谱分离纯化后,氮气吹干供进一步衍生化,衍生化产物用GC/NCI/MS检测,获得标记与未标记VA的丰度比,最后利用Furr-Olson公式计算VA肝脏储备量。在优化的条件下,血清样本中VA的回收率大于85%,精密度(RSD, n=6)小于10%,定量限为26.4 μ g/L,基本满足口服1 mg ²H₈-RAC后标记与未标记VA的检测要求。相比国内现行的人体VA评价方法,该方法能更客观地反映人体VA营养水平。该项测定技术与VA干预实验相结合,可获得某一人群维持体内VA稳定储备水平的膳食摄入量水平。同时,稳定同位素示踪技术的运用对促进经口摄入的VA源在体内生物转化效率的研究也起着重要作用。     

Automated determination of traces of mercury in biological materials by substoichiometric radioisotope dilution

Solid samples (1-2 g) are burned in oxygen in a flask containing radiomercury in dilute hydrochloric acid, in which the non-active mercury to be determined is immediately absorbed. All mercury is subsequently extracted by dithizone in carbon tetrachloride and then re-extracted into dilute hydrochloric acid. This aqueous phase is further analysed automatically (AutoAnalyzer, 20 samples hr ) as previously described. Liquids (up to 100 ml) are analysed in the same way but instead of being burned in oxygen are first oxidized with potassium permanganate in acid medium. Quantities between 2 and 0.00004 ppm Hg were determined in various materials. Results for international biological standards agreed well with values obtained by activation analysis: kale 0.159 ppm Hg (relative standard deviation 2%) and IAEA cereals 0.0435 ppm Hg (+/- 5%). The new method is far more simple and rapid than activation analysis and just as sensitive; it is therefore more suitable for routine work. About 100 samples can be analysed per day.     

Determination of trace elements in semiconductor materials by neutron activation analysis using the radioisotope addition technique

The determination of trace elements in highly activated matrix components was carried out by neutron activation analysis using the radioisotope addition technique. The method is based on the addition to the irradiated test sample of a radioisotope which is a diffeent nuclide of the element to be determined. After separation, the chemical yield is calculated from the radioactivity added and the element is determined by an ordinary technique. Twelve elements in indium phosphide and eight elements in gallium arsenide could be determined by the method.     

Radioactive ore analysis by optimized radioisotope X-ray fluorescence technique

A method for analyzing U and Th in radioactive ores by radioisotope excited X-ray fluorescence is described. For the proposed analysis, the theoretical and experimental factors that affect the sensitivity of the radioisotope XRF technique were investigated. Minimum detection limits of 13 ppm and 108 ppm can be achieved for U and Th, respectively, with a total counting time of 1000 s on a powdered ore sample. Results obtained in the analyses of radioactive ores from Turkey and BL-5 candidate reference uranium ores from CANMET (Canada Centre for Mineral and Energy Technology) are reported.     

Determination of rare-earth elements in rocks by spark source mass spectrometry and isotope dilution after ion-exchange separation in mixed solvents

Summary Rock samples are dissolved in the presence of spikes of isotopically enriched rare earth elements. The REE are separated as a group by a mixed-solvent anion-exchange procedure, mixed with high-purity gold powder and analysed by spark source mass spectrometry with either photoplate or electrical detection. Precision and accuracy of the isotope dilution spark-source mass-spectrometric procedure are evaluated to be in the ± 3 to ± 5 % range, by analysing standard rock samples.

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Bestimmung der Seltenen Erden in Gesteinen durch Funken-Massenspektrometrie und Isotopenverdünnung nach Abtrennung durch Ionenaustausch in gemischten Solventen

Zusammenfassung Die Gesteinsproben werden mit isotopenangereicherten spikes der Seltenen Erden gemischt und gelöst. Die Seltenen Erden werden als Gruppe durch Ionenaustausch in gemischten Solventen abgetrennt, mit reinem Goldpulver gemischt und mittels Funken-Massenspektrometrie analysiert. Der Nachweis geschieht entweder mit Photoplatten oder elektrisch. Untersuchungen an Standard-Gesteinsproben zeigen, daß die Reproduzierbarkeit und die Genauigkeit des beschriebenen Isotopenverdünnungs-Funken-Massenspektrometrischen Verfahrens im Bereich von ± 3 bis ± 5 % liegen.

     

The determination of lithium in rocks by the method of stable isotope dilution

A method is described for the determination of lithium in rocks by the method of stable isotope dilution. 50 mg to 500 mg of the sample are used for each determination. The sample is mixed with a known quantity of enriched lithium and is then decomposed by a mixture of hydrofluoric and perchloric acids. The separation of the alkali metals from iron and aluminium is based on the thermal decomposition of the perchlorates. For mass spectrometric measurements it is not necessary to separate the lithium from the other alkali metals.The values obtained for the lithium contents of two standard rocks are: G-I, 21.3 p.p. m. ; W-I, 12.6 p.p.m. Independent determinations, made using both lithium 6 and lithium 7 as tracers, have established that no significant systematic errors are caused by isotopic fractionation.Results obtained for two clay samples containing 0.1–0.3% of lithium show good agreement with spectrographic values.     

Determination of nickel,gold and silver in gallium arsenide by radioactivation analysis based on the quantitative isotope dilution principle

A method of radioactivation analysis has been developed for the determination of Ni, Au and Ag impurities in gallium arsenide. The separation and substoichiometric extraction of these elements were studied and analytical procedures are suggested for their determination. All components are separated by suitable procedures and determined by substoichiometric methods. Ni is extracted as diethyldithiocarbamate into toluene, Au as a complex of rhodamine-B in chloroform, and Ag as dithizonate in carbon tetrachloride. The contents of Ni, Au and Ag in a gallium arsenide crystal with a carrier concentration of 1.8·10¹⁶/cm³ were 0.05–0.08, 0.006–0.008 and 0.002–0.005 ppm, respectively.     

Determination of trace elements in water by radioisotope alpha-particle induced X-ray emission

An X-ray spectrometric system including²¹⁰Po -particle sources for excitation and a Si(Li) detector has been applied to determine the concentrations of trace elements in water samples. Thin targets were prepared by the evaporation of a known volume of water deposited on a Mylar backing. The system was calibrated using the internal standard method. Relative sensitivities were measured for 16 elements detected by their K, L and M X-rays. The results are compared with theoretical calculations. The minimum detection limits from 0.01 to 0.07 g/ml were obtained for 2000 s analysis time.     

Determination of silver in lead by neutronactivation analysis

Submicrogram amounts of silver have been determined in lead by neutron-activation analysis. The activity of the ¹¹⁰Ag isotope was measured by following the decay of the 0·66-MeV gamma ray. Reproducibility was generally better than 10%. The smallest amount of silver determined was approximately 0·02 μg. The analyses were completed within 15 min.     

Determination of iodide in drinking water by isotope dilution analysis

The most suitable way of determination iodine-deficiency is to measure iodine concentrations in water and urine. For this reason, a method that can determine iodide concentrations in drinking water and suitable for routine analysis, is developed. Water samples have been collected from four Aegean localities: Izmir, Salihli, Ödemis and Tire situated in the western Turkey. The method is based on substochiometric isotope dilution analysis. Iodile concentrations vary within 9.86–85.14 μg/l ranges in the analyzed samples. Mean value is 44.92±22.07 μg/l.     

GC-MS/NCI稳定同位素稀释技术检测动物源性食品中氯霉素的残留量

建立了一种用于各种动物源性食品中氯霉素残留量的气相色谱-负化学离子源质谱(GC-MS/NCI)检测方法。以氘代氯霉素(D5-CAP)为内标物,用乙酸乙酯对各类样品中的氯霉素进行提取,用正己烷和40 g/L NaCl溶液液液分配除脂肪,基质复杂的样品再用Oasi HLB固相萃取柱净化,经硅烷化衍生后由GC-MS/NCI在选择离子监测模式下进行测定。多数样品在0.2,0.5,1.0μg/kg3个添加水平下氯霉素的回收率处于87.8%和107.0%之间,相对标准偏差(RSD)不大于8.5%。方法在2.0~80.0μg/L范围内有良好的线性关系,基质复杂样品中氯霉素残留的检出限达到0.1μg/kg,基质简单样品的检测限可达0.05μg/kg。方法适合各种动物源性食品中氯霉素残留量的确证分析。     

Determination of silver in alloys by controlled-potential electrolysis at a tantalum electrode

A versatile method for the determination of Ag is described. It is based on controlled-potential electrolysis with a tantalum cathode in the presence of lactic acid at pH 2-6. An SCE of double-junction type with sodium formate bridge electrolyte is used as the reference electrode. The role of washing after electrolysis is studied and a novel technique suggested. The standard deviation of the determination is 0.13 mg. A preliminary separation is needed only if W is present. The proposed method has been satisfactorily applied to the analysis of a large number of silver alloys with different compositions.