Atomic-absorption spectrophotometric determination of trace amounts of arsenic in acrylic fibres containing antimony oxide with solvent extraction and arsine generation

Abstract

An arsine generation atomic-absorption spectrophotometric method is described for the determination of 0.04–400 p.p.m. of arsenic in acrylic fibre samples containing antimony oxide. The interferences from antimony and other elements are eliminated by solvent extraction with benzene. The sample is digested with a mixture of concentrated nitric, perchloric and sulphuric acids. Arsenic(V) obtained by the digestion is then reduced to arsenic(III) with titanium(III) chloride. After the reduction of arsenic and antimony, arsenic(III) is extracted into benzene from a sulphuric acidhydrochloric acid mixture, from which no antimony(III) is extracted. Arsenic(III) in the benzene phase is further back-extracted into water. Arsine is generated with potassium iodide, tin(II) chloride and zinc powder from 2.4 N hydrochloric acid solution and introduced into a nitrogen hydrogen flame of an atomic-absorption spectrophotometer. The method has been tested with various acrylic fibre samples containing antimony oxide, and the limit of detection and precision achieved are 0.04 p.p.m. for 1 g of sample and 7%(relative standard deviation), respectively.