Flow-injection anodic stripping voltammetry at a gold electrode for selenium(IV) determination

A continuous method for the determination of selenium based on flow-injection anodic stripping voltammetry is proposed. After the deposition/preconcentration of Se(IV) on a gold working electrode at an applied voltage of — 0.4 V, an anodic scan from —0.4 to 1.16 V was applied, whereby the selenium was stripped at a potential of 0.912 V. The current produced was proportional to the Se(lV) concentration in the sample. Off-line reduction of Se(VI) to Se(IV) gave the original Se(IV) + Se(VI) concentration so that the Se(VI) concentration could be calculated as the difference between the two results. Interfering divalent cations were removed by on-line separation by use of a cation exchange column prior to the injection valve. The method has a linear determination range between 5 and 100 ng ml−1 with a correlation coefficient, r2, of 0.9969 and an R.S.D. < 4.7%. A certified reference material and Se(IV) and Se(VI) added to water samples give excellent recoveries.