Determination of inorganic arsenic species in aqueous samples by ion-exclusion chromatography with electro-chemical detection

Abstract

Arsenic(III) and -(V) were separated by ion-exclusion chromatography, using 0.01 M orthophosphoric acid eluent. Both forms of arsenic can be monitored by UV detection at 200 nm, but sensitivity is poor. Amperometric detection with a platinum-wire electrode at an applied potential of + 1.00 V allows arsenic(III) to be determined down to 0.012 μ M. Detector response was shown to be linear to 1.00 μ M, at which concentration, ten replicate injections of arsenic(III) gave a relative standard deviation of 1.3%. In an application of the chromatographic procedure with amperometric detection to analysis of bottled mineral waters, arsenic(III) was measured by direct injection, and total inorganic arsenic was determined as arsenic(III) after reduction of arsenic(V) by sulphur dioxide