Determination of nanogram amounts of iodide by electrochemical isotope dilution analysis

An isotope dilution method involving electrodeposition to determine nanogram quantities of iodide has been developed. A known quantity of iodide in ethanol as solvent was labelled with¹³¹I⁻ and subsequently diluted with a predetermined amount of inactive iodide. Specific activities before and after the isotope dilution were established by anodically depositing small fractions of the halide in each sample on rotating silver micro electrodes and determining the activities of the electrodeposits. Amounts from 42 ng to 1 μg were determined, usually with an error of less than 2.5%.     

Determination of iodide in common salts consumed in Turkey by isotope dilution analysis

Iodide traces in common salts consumed in Turkey have been determined by isotope dilution analysis. Iodide was precipitated by stoichiometric amount of AgNO₃. Iodide-131 was used as tracer. Electrophoresis was performed to separate Ag¹³¹I from excess¹³¹I⁻. Zone of Ag¹³¹I was cut off electrophoresis paper and counted with a NaI(Tl) scintillation counter. Count rates were plotted versus added KI concentrations. Unknown iodide amounts were found by using these linear plots. Iodide concentrations found in analyzed salts were 9–58 μg/g.     

Iodine measurements by isotope dilution analysis in drinking water in Western Turkey

This study was designed to evaluate iodine concentrations in drinking water samples using isotope dilution analysis (IDA) in the Aegean region of Turkey A total of 76 drinking water samples from rural and urban areas in regional cities were analyzed. The mean iodine concentration was 78±27 μg/l and iodine concentration ranges were within 69±26 μg/l and 103±6 μg/l.     

Determination of microamounts strontium by substoichiometric isotope dilution analysis

The isotope dilution with substoichiometric separation for the determination of strontium has been investigated. Strontium can be extracted with a substoichiometric amount of bis-1,2-dicarbollylcobaltate in nitrobenzene in the presence of 15-crown-5. It has been found, that Li⁺, Mg²⁺, Ca²⁺ and Fe³⁺ do not interfere in the strontium determination but the high extraction of K⁺, Na⁺ and NH₄ ⁺ ions results in marked influence.     

Determination of zinc in environmental water by displacement substoichiometric isotope dilution analysis /DSIDA/

Trace amounts of Zn /ng.ml^–1/ were determined using a displacement reaction of /Zn²⁺/ org from the dithizone organic phase into the aqueous phase, with a substoichiometric amount of /Hg²⁺/ aq. The results were compared with direct substoichiometric IDA. Absorption spectrophotometry was used as a reference analysis.     

Determination of cadmium by sub- and super-equivalence isotope dilution analysis

Trace amounts of cadmium were determined by sub- and super-equivalence isotope dilution analysis in model solutions and water samples. Cd/II/ was labelled with¹⁰⁹Cd and was extracted in CHCl₃ as dithiozonate. AAS was chosen as reference analysis.     

Determination of microamounts of barium by isotope dilution analysis with substoichiometric separation

In an open neutron reflection setup there are some basic design parameters that have an important influence on the value of the sensitivity. The effects of variations of such parameters in the sensitivity (S) were calculated applying the Monte Carlo N-particle transport code system MCNP-4A.     

Determination of rare earth impurities in high purity uranium by isotope dilution analysis

Summary An isotope dilution method for the determination of rare earth impurities in uranium has been developed and Ce, Nd, Sm, Eu and Gd have been determined in uranium oxide samples. The method involves isotopic dilution with enriched isotopes of the rare earths being measured, followed by the separation of rare earths from uranium. A mass spectrometer with thermionic source was used to determine the relative isotopic abundances in each of these rare earths. All these five elements were analysed selectively by preferential evaporation technique. Trace concentrations down to parts per billion range can be measured with good sensitivity and accuracy.

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Bestimmung von Verunreinigungen an Seltenen Erden in hochreinem Uran durch Isotopenverdünnungsanalyse

Zusammenfassung Eine Isotopenverdünnungsmethode wurde ausgearbeitet zur Bestimmung von Ce, Nd, Sm, Eu und Gd in Uranoxidproben. Das Verfahren umfaßt isotopische Verdünnung mit angereicherten Isotopen der zu bestimmenden Elemente und nachfolgende Abtrennung der Seltenen Erden von Uran. Die relativen Isotopenhäufigkeiten wurden mit Hilfe eines Massenspektrometers mit thermischer Ionenquelle bestimmt. Alle fünf Elemente wurden durch selektive Verdampfung analysiert. Spurenkonzentrationen bis herab zum ppb-Bereich konnten mit guter Empfindlichkeit und Genauigkeit erfaßt werden.

     

Determination of trace elements and radioactive materials by substoichiometric isotope dilution analysis

Substoichiometric isotope dilution analysis has been applied for the determination of trace elements in liquid samples, of carrier content in radioisotope solution and of concentration of organic reagent. Cu in mineral acids and in ZnSe single crystal was determined by the substoichiometric extraction with dithizone. The values of 1.8 and 0.018 ppm in nitric acid and distilled one and of 1.4 and 0.44 ppm in ZnSe were obtained. Cu and P carrier contents in⁶⁴Cu and³²P solutions were determined by the substoichiometric extractions with dithizone in CCl₄ and with molybdic acid into MIBK in the series of the solutions adding various amounts of Cu or P carrier. An analogous method has been applied for the determination of dithizone and diethyldithiocarbamate solutions. The method was also applied for the determination of⁶⁰Co radioactivity in environmental samples. The analytical result of water samples is described.     

Determination of fluorine in water samples by spiking isotope dilution and adsorption on glass beads

A rapid method for the radiometric determination of fluoride concentration in aqueous solutions is presented. The method depends on the chemisorption of HF on a glass adsorber from a dilute acid solution, which has been spiked with¹⁸F. The limit of the determination is 0.03 μg/ml. Applications to surface water and urine samples are discussed.     

Determination of arsenic in germanium by the combination of isotope dilution and activation analysis

The determination of arsenic by activation analysis in germanium may be disturbed by arsenic isotopes formed in the irradiation of the germanium matrix itself. The isotopic dilution technique will eliminate such interferences, but it requires weighing of very small masses of arsenic, after appropriate chemical separation. This weighing procedure can be avoided if the mass of the recovered arsenic is determined by activation analysis. In order to apply such a procedure, a known amount of arsenic labelled with⁷⁶As, whose specific activity is also known, is added to the germanium sample to be analysed. The sample is processed, the arsenic separated, and the chemical yield established. The recovered mass of arsenic is then determined by activation analysis applying the classical isotopic dilution analysis formula. The accuracy precision and linearity of the method are discussed.     

Iodine determination in milk by isotope dilution analysis

Iodine is an essential trace element in the human diet. It is utilized in the synthesis of L-monoiodothyrosine, which is a precursor of the thyroid hormones, thyroxin and triiodothyronin. In this study, a method that can determine iodine concentrations in milk has been developed. The method is based on substoichiometric isotope dilution analysis (IDA). Iodine concentrations were measured in milk, which has been collected from three big cities and environment municipalities of Aegean Region. The iodine concentration ranges were within 436.8 and 896.7 μg/kg in milk samples. Mean iodine concentration was not greatly changed from season to season, between 1998 and 2002. This revised version was published online in August 2006 with corrections to the Cover Date.     

Determination of magnesium at trace levels by isotope dilution

A mass spectrometric method for the isotopic analysis of magnesium and its determination at low concentrations in the presence of an excess of other elements is described. The lowest level at which magnesium was determined was 1 ppm with a precision and error +/- 1%.     

Redox substoichiometry in isotope dilution analysis

The oxidation reaction of antimony(III) with potassium dichromate has been investigated radiometrically. The quantitative oxidation of antimony(III) was found to be not disturbed even in large amounts of tin(IV). On the basis of these results the redox substoichiometric isotope dilution analysis using potassium dichromate as the oxidizing agent was proposed for the determination of antimony in metallic tin. The antimony content of 1.22±0.05 μg in metallic tin (10 mg) was determined without separation of the matrix element.     

Redox substoichiometry in isotope dilution analysis

Radiometric titration of antimony(III) with potassium bromate in hydrochloric acid media using the standard series method provided much valuable informations on the titration errors which depended on the concentrations of the acid and antimony(III). The hydrochloric acid concentrations between 2.5 and 3.0M were found to be optimum for the oxidation of antimony(III) amounts of 4 μg or less. Under these optimum reaction conditions the redox substoichiometric isotope dilution analysis was applied to the determination of antimony in metallic zinc and the satisfactory results were obtained, without the separation of matrix element. Also, the merits of various oxidizing agents hitherto studied for the quantitative oxidation of antimony(III) were compared and discussed.     

Redox substoichiometry in isotope dilution analysis

Isotope dilution analysis using the redox substoichiometric principle has been applied to the determination of antimony content in metallic zinc. As the substoichiometric reaction, the oxidation of trivalent to pentavalent antimony with potassium permanganate was used, followed by separation of these species by the BPHA extraction of trivalent antimony. Determination of antimony contents less than 0.5 μg was found to be possible with good accuracy, without separation of zinc ions. The antimony content in metallic zinc was determined to be 19.7±0.8 ppm, in good agreement with the results obtained by the other analytical methods.     

Determination of fission product ruthenium by isotope dilution mass spectrometry

Isotope dilution mass spectrometry using enriched isotope⁹⁶Ru as a spike was applied to the determination of ruthenium as a fission product. Ruthenium in the solution was oxidized to RuO₄ by Ce/IV/ and separated from coexisting metal elements by distillation. Silica-gel technique was employed to enhance ion current of ruthenium in the mass spectrometric measurement. The lower detection limit was 0.005 g ml^–1 and the relative standard deviations /n=3/ for 1.2 and 0.05 g ml^–1 of ruthenium were 0.2 and 0.5%, respectively.     

Determination of caesium microamounts by isotope dilution with substoichiometric separation

Selectivity of isotope dilution analysis with substoichiometric separation for caesium determination has been investigated. Caesium can be extracted with a substoichiometric amounts of bis 1,2-dicarbollylcobaltate in nitrobenzene in the presence of dibenzo-18-crown-6. The method is selective. Other metal ions (K⁺, Na⁺, Mg²⁺, Ca²⁺, Fe³⁺, Al³⁺) do not interfere.