Flow injection spectrophotometric determination of ultra trace amounts of selenium(IV)

105-107A flow injection spectrophotometric method has been described for determination of selenium(IV). The method is based on the catalytic effect of Se(IV) on the reduction of gallocyanine by sulphide. The decrease in absorbance of gallocyanine at 620 nm is proportional to the Se(IV) concentration in the range 2.5- 500 ng/mI with a limit of detection of 1.0 ng/mI. The relative standard deviation for ten replicate measurements of 50 ng/mI of Se(IV) is 1.5%. Interference due to various ions has been studied