Spectrophotometric determination of arsenic in environmental and biological samples

Abstract

A simple and sensitive spectrophotometric method has been developed for the determination of arsenic using variamine blue as a chromogenic reagent. The method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine, which oxidizes variamine blue to form a violet coloured species having an absorption maximum at 556 nm. Beer’s law is obeyed in the range 0.2-14 μg mL^-1 of As(III). The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit were found to be 1.43<img src='/image/spc_char/cross.gif' border=0>10⁴ L mol^-1cm^-1, 5.26<img src='/image/spc_char/cross.gif' border=0>10^-2 μg cm^-2, 0.022 and 0.072 μg mL^-1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples.