The application of substoichiometric radioisotopic dilution principles to controlled-potential coulometry and solvent extraction

Radioisotope dilution principles are applied to controlled-potential electrolysis and solvent extraction with dithizone for the determination of trace amounts of cadmium. A method was developed to verify whether or not the substoichiometric principle was obeyed. If the substoichiometric principle was not obeyed, analysis was still possible by means of calibration curves. In order to obtain independent verification of the series controlled-potential method and to establish a means of comparison with the radioisotope dilution technique a current integration procedure was also employed. A microtechnique was used to extend the sensitivity of the solvent extraction system for cadmium. Standard zinc spelter and high-purity zinc were analyzed for cadmium after separation by a method of standard addition.     

Radiometric determination of trace amounts of zinc using liquid scintillation counting

A sensitive and selective radiometric method of substoichiometric isotope dilution analysis for the determination of trace amounts of zinc is described. The activity of (65)Zn used as a tracer in this method was measured by liquid scintillation counting and its counting efficiency was found to be 76+/-2.7%. The method is based on the extraction of the ion-association complex of zinc from thiocyanate medium at pH 7.9 using substoichiometric amount of Aliquat-336 in toluene. The method is sensitive to 20 ng of Zn(II) in an aqueous phase volume of up to 15 ml and its reliability was tested by applying it to a certified reference material-magnesium alloy and pharmaceutical samples.     

Substoichiometric determination of zinc by the isotope-dilution method using a chelating agent-loaded resin

A substoichiometric method for the determination of zinc has been developed. Zinc can be separated from other cations by using an anion-exchanger loaded with a substoichiometric amount of 8-quinolinol-5-sulphonic acid. Interfering metals can be removed beforehand by dithizone extraction. The feasibility of this method for water analysis was also examined.     

The determination of zinc by substoichiometric isotope dilution

Recently, R??I?KA et al. proposed a determination of zinc in highly pure germanium dioxide by a substoichiometric extraction technique. In the present work, the effects on the substoichiometric extraction of equilibrium time, pH and interfering ions were investigated by radioactive tracer techniques and spectrophotometric measurements. The sensitivity of the procedure is limited by the blanks and the addition of oxalate ions can give rise to inaccurate results. The specific activity of ⁶⁵Zn was also determined by substoichiometric extraction.     

Substoichiometric determination of zinc with thiocyanate and brilliant green

A method for the determination of microgram amounts of zinc has been developed. This is based on the substoichiometric extraction of its ion-association complex with brilliant green into benzene from thiocyanate solution.     

Solvent extraction of cadmium/II/ with 2-mercaptobenzothiazole into methyl iso-butyl ketone

The extraction of cadmium/II/ with 2-mercaptobenzothiazole /2HMBT/ into methyl iso-butyl ketone has been studied. The effect of various parameters on the extraction coefficient value such as effect of pH, time of equilibration, effect of anions and cations have been evaluated. The stiochiometry of the extracted species obtained by the method of substoichiometric extraction and mole ratio method was found to be 1:2. Decontamination factors for a number of elements in the substoichiometric extraction of Cd/II/ were also obtained.     

Comparative substoichiometric extraction of zinc with potassium salts of ethyl,propyl, butyl,pentyl and benzyl xanthates

The comparative extractability of zinc with potassium salts of ethyl, propyl, butyl, pentyl, and benzyl xanthates from the pH range of 3.5–9.0 into chloroform has been studied, employing a sensitive and rapid substoichiometric radiochemical method. The extent of reproducibility was tested in each case. The effect of associated ions on the extraction was studied. The amount of zinc present in the standard solutions was determined employing each xanthate separately. The zinc content present in geological water samples in and around Tirupati was determined by the method developed and compared with the values obtained by Atomic Absorption Spectrophotometry.     

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.     

A study on the solvent extraction of Ag/I/ with 1,2,3-benzotriazole in chloroform

A rapid and selective method has been developed for the substoichiometric extraction of Ag/I/with 1,2,3-benzotriazole /1,2,3-BT/ in chloroform in the presence of versenate. The effect of various parameters such as pH, time of equilibration, solvent, anions, cations, etc., on the extraction coefficient value has been studied. The stoichiometry of the extracted species of 11 /Ag:1,2, 3-BT/ was obtained by the slope ratio method and substoichiometric extraction. Decontamination factors for most elements in the substoichiometric extraction of Ag/I/ were found to be higher than 10⁴.     

Solvent extraction of Ni/II/ with isonitrosobenzoylacetone into chloroform

A method has been developed for the quantitative extraction of Ni/II/ with isonitrosobenzoylacetone /HINBA/ into chloroform. The effect of various parameters on the extraction coefficient value such as pH, time of equilibration, effect of solvents, anions, cations etc. have been studied. The stoichiometry of the metal: reagent determined by the method of substoichiometric extraction and slope ratio method was found to be 12. Decontamination factors for many elements in the substoichiometric extraction of Ni/II/ were also evaluated.     

A study on the solvent extraction of Cd/II/ with 1,2,3 benzotriazole into n-heptanol

The extraction of cadmium/II/ with 1,2,3 benzotriazole /2-BT/ into n-heptanol has been studied. The effect of various parameters such as effect of pH, time of equilibration, effect of anions on the extraction coefficient values have been evaluated. The stoichiometry of the extracted species by the method of substoichiometric extraction and slope ratio method was found to be 12. Decontamination factors for a number of elements in the substoichiometric extraction of Cd/II/ were also obtained.     

Displacement substoichiometric separations in radioanalytical chemistry

The principle of displacement substoichiometry and the possibilities of its practical use have been outlined. The substoichiometric separation of lead, arsenic, and zinc can be carried out by applying diethyldithiocarbamate complexes and solvent extraction.     

Substoichiometric determination of traces of gold by radioactive isotope-dilution analysis

A radioactive isotope-dilution method for the determination of traces of gold has been developed. It is based on the solvent extraction of gold diethyldithiocarbamate from 0-5N sulphuric acid containing ascorbic acid, by means of a substoichiometric amount of zinc diethyldithiocarbamate in chloroform. The separation has been applied to the analysis of gold-doped semiconductor-grade silicon and of gold-bearing ores. Amounts of gold down to 5 x 10(-7)g 20 ml of test solution can be determined.     

Solvent extraction of Ru(III) with 2-mercaptobenzimidazole into n-butanol

A new and rapid method has been developed for the quantitative extraction of Ru(III) with 2-mercaptobenzimidazole into n-butanol. The extraction coefficient of Ru(III) between n-butanol and an ethanolic solution of 1% 2-mercaptobenzimidazole showed a maximum value ofE=161 at a pH of 2.0. The effect of various other parameters on the extraction coefficient value of Ru(III) such as solvent effect, anions, cations, etc. have also been studied. The stoichiometry of metal to reagent has also been determined by the method of substoichiometric extraction and by the slope ratio method and was found to be 1∶3. Decontamination factor for various elements in the substoichiometric extraction of Ru(III) were also evaluated.     

A study on the solvent extraction of Se/IV/ with 2-mercaptobenzothiazole into chloroform

The extraction of Se/IV/ from hydrochloric acid medium with 2-mercaptobenzothiazole/2-HMBT/into chloroform has been studied. The effect of various parameters on the extraction coefficient value such as molarity of hydrochloric acid, time of equilibration, effect of cations and anions etc., has been evaluated. The stoichiometry of the extracted species was determined by the method of substoichiometric extraction and slope ratio method and was found to be 1∶4. Decontamination factors for many elements in the substoichiometric extraction of Se/IV/ was also obtained.     

Substoichiometric determination of manganese in a synergistic extraction system and its application to the analysis of biological materials

The substoichiometric isotope dilution analysis for manganese(II) in a synergistic extraction system of a chelating agent and a neutral ligand is described. The substoichiometric extarction is based on a substoichiometric amount of 2-thenoyltrifluoroacetone and an excess of 1,10-phenanthroline. The recommended condition and the reproducibility of the present system were examined. The present method was applied for NBS-SRM tomato leaves and NIES-SRM chlorella, and very good results with high accuracy and precision were demonstrated.     

Solvent extraction of Sb(III) with malachite green into chloroform

A rapid and selective method for the solvent extraction of Sb(III) using malachite green (C. I. Basic green 4) has been described. Effect of different parameters affecting the extraction coefficient value of Sb(III) such as acidity, time of equilibration, KI concentration, solvents, anions, etc. has been studied. For various elements the separation factor has been evaluated. The stoichiometry of the extracted species has been determined by the method of substoichiometric extraction. The decontamination factor for some elements using substoichiometric quantities of the extracting agent has been evaluated. Radiotracers were employed for the extraction studies. The method elaborated has been employed for the quantitative determination of antimony in normal, benign and cancerous tissues of the human brain.     

Substoichiometric determination of trace impurities in zinc selenide

Determination of trace impurities in zinc selenide was carried out by substoichiometric neutron activation analysis. Trace impurities were separated from matrix elements by suitable procedures and determined by substoichiometric methods, i.e., Au was extracted with rhodamine-B, Ag and Cu with dithizone, Cr with sodium diethyldithiocarbamate, Co with 1-nitroso-2-naphthol, and Sb with cupferron. Two sorts of zinc selenide single crystals were supplied for analysis and the following values were obtained as impurity concentration; Au 0.36, 0.076 ppb, Ag 42, 32 ppb, Cr. 1.8, 0.63 ppm, Co 0.16, 0.0079 ppm, Sb 8.5, 5.9 ppb and Cu 1.4, 0.44 ppm. The behavior of copper by heat-treatment of zinc selenide was also studied by means of substoichiometric isotope dilution analysis.     

Substoichiometric isotope dilution analysis for uranium by synergic extraction

Substoichiometric extraction of uranyl ion in a synergic system of a chelating reagent and a neutral ligand is described. The system is based on a substoichiometric amount of 2-thenoyltrifluoroacetone (TTA) and an excess of tributylphosphate (TBP); this is compared with a system involving a substoichiometric amount of trioctylphosphine oxide and an excess of TTA. The reproducibility of the substoichiometric extraction is 0.46 or 0.62%, respectively. The former method is superior because extraction of uranyl ion with TBP alone is negligible. The method is applicable to > ca. 10 μg of uranium.     

A study on the solvent extraction of Hg/II/ with 2-mercaptobenzothiazole into chloroform

The extraction of mercury/II/ with 2-mercaptobenzothiazole /2-HMBT/ into chloroform has been studied. The effect of various parameters on the extraction coefficient value such as effect of pH, time of equilibration, effect of anions and cations have been evaluated. The stoichiometry of the extracted species obtained by the method of substoichiometric extraction and slope ratio method was found to be 1∶2. Decontamination factors for a number of elements in the substoichiometric extraction of Hg/II/ were also obtained.