Spectrophotometric Determination of Trace Amounts of Sulfide Ion Based on Its Catalytic Reduction of Toluidine Blue

Abstract

A simple, rapid, and sensitive method has been developed for the determination of trace sulfide (0.28–1.7 μg cm⁻³) based on its catalytic reduction of Toluidine Blue in the presence of Se(IV). The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of the dyestuff at 628 nm by the fixed time method. The limit of detection is 50 ng cm⁻³ and the relative standard deviation for 1 μg cm⁻³ sulfide is 2.4%. The method was applied to the determination of sulfide in spring water.