ABSTRACT
Formation of piazselenols by the reaction of Se(IV) with 1,2-diaminobenzene and its derivatives, followed by solvent extraction and gas chromatography with electron-capture detection, provides the most sensitive means of determining selenium. By suitable chemical manipulation, the method can be used for Se(-II), Se(O), Se(IV) and Se(VI). Applications to a wide variety of samples are reviewed.
Subject(s)
Selenium/blood , Adult , Aged , Chromatography, Gas/methods , Female , Humans , Infant, Newborn , Male , Middle AgedABSTRACT
1,2-Diaminobenzene and its derivatives react with selenous acid in acidic solution to form the piazselenols, which can be extracted into toluene. Microgram amounts of selenium can be determined spectrophotometrically by measuring the absorbance of these piazselenols extracted into toluene. A more sensitive method, in which the piazselenols extracted into toluene are detected by electron-capture gas chromatography, has been developed. In order to find a more sensitive reagent, 13 piazselenols were synthesized. The retention behaviour and sensitivity in electron-capture detection gas chromatography and the distribution ratios between aqueous solution and toluene were studied for each piazselenol extracted into toluene. Of these piazselenols, 4,6-dibromopiazselenol, formed by the reaction of 1,2-diamino-3,5-dibromobenzene with selenous acid, was found to be best as regards sensitivity and distribution ratio. Under the optimal conditions for the formation and the extraction of the piazselenol, the practical detection limit was 1 ng. Selenium(VI) and total selenium in NBS Bovine Liver, SRM 1577, were determined successfully.
Subject(s)
Aniline Compounds , Bromobenzenes , Liver/analysis , Selenium/analysis , Animals , Cattle , Chemical Phenomena , Chemistry , Chromatography, Gas , Indicators and Reagents , MethodsSubject(s)
Albumins/analysis , Milk/analysis , Selenium/analysis , Animals , Chromatography, Gas , Indicators and Reagents , Nitrobenzenes , PhenylenediaminesABSTRACT
Ultramicro amounts of selenium in pure sulphuric acid are converted into selenous acid with a bromine-bromide redox buffer solution. The selenous acid reacts quantitatively with 4-nitro-o-phenyl-enediamine to form 5-nitropiaselenol which can be extracted into toluene. The extract is very sensitive to electron-capture detection in gas chromatography, and the sensitivity is higher than that of 5-chloro-or 4, 5-dichloro-piaselenol. The calibration curve (peak heights) is linear up to 0.15 mug of selenium in 1 ml of toluene. Pure sulphuric acid, commercially available, contains 10(-6)$ 10(-5) % selenium.
