EXTRACTION CONCENTRATING OF SCANDIUM (III) IN COMPLEX FORM WITH 2-HYDROXY-5-T-BUTYLPHENOL-4-METOXYAZOBENZENE AND ITS DETERMINATION BY ATOMIC-ABSORPTION SPECTROMETRY

Complexation of scandium 2-hydroxy-5-T-butylphenol-4-metoxyazobenzene (HR) was studied by atomic-absorption and spectrophotometric methods. Optimum conditions of formation and extraction of the complex were found. Maximum light absorbance of a complex in n-butanol is in the range of 470÷480 nm. Molar absorption coefficient equals to (2.2–3.0).104. Stability constant of scandium in n-butanol is л=2.8·1010. Selective and sensitive techniques of extraction-atomic absorption determination of scandium in soils were developed

Extractive separation of selenium for atomic-absorption determination in purified sulfur

The expanding use of sulfur in medicine, science and technology has tightened the requirements for the impurity composition, including the content of selenium in sulfur. Combined extraction-atomic absorption methods have been developed to determine selenium in purified sulfur. The possibility of using thiourea derivatives such as sodium diethyldithiocarbamate and diphenylthiocarbazone for the extraction of microgram amounts of selenium from sulfuric acid solutions was studied. Optimal conditions for the extraction of selenium from sulfate solutions are determined. Two procedures for selenium separation are proposed: extraction of selenium diethyldithiocarbamate with ethyl acetate from a solution of sulfuric acid with pH 3 or extraction of selenium dithizonate with chloroform from a 5.25 – 6.0 M sulfuric acid solution. The results of the extraction-atomic absorption determination of selenium in sulfur are compared for both procedures of selenium separation. The accuracy of the selenium determination in purified sulfur is confirmed by the method of varying sample weight. The optimal temperature-time parameters for the electrothermal atomic absorption determination of selenium are determined. The limit of selenium determination is 1 × 10–5 % wt. The values of sr in the range of selenium content 2 × 10–5 — 1 × 10–4 % wt. change from 0.10 to 0.12.

New Atomic Absorption Methods for Metals Determination in Aviation and Automotive Gasoline

New methods for direct atomic absorption determination of lead and lithium as antiknock additives components in aviation and automotive gasoline in the concentration ranges 100–1700 (Pb) and 2.5/0.25–100 (Li) mg/L have been developed. To overcome the difference in analytical signals for samples and standard solutions due to concentration values and matrix effects the proper sample dilution and the addition of the blank as pure reagent hydrocarbons mixture in the solutions have been offered. The methods have high precision, are simple and may be recommended for gasoline quality control and identification procedures.

Control of residual amounts of copper-containing pesticides in plant products

Relevance and methods. Methodological approaches to assessing the residual amounts of copper-containing pesticides in plant products against the background of natural copper content are presented. The conditions for obtaining reliable results when conducting a hygienic assessment of the content of residual amounts of the active substance are determined. The developed scheme for determining the residual amounts of copper-containing pesticides includes the homogenization of the analyzed material by shredding with dry ice and microwave mineralization of samples with subsequent flameless atomic absorption determination of copper.Results. Data on the levels of natural copper content in samples of potatoes, onions, cucumbers, tomatoes and grapes of various varieties and growing areas are presented. The possibility of applying the developed approaches to study the dynamics of accumulation of active substances during the growing season is shown.