Spectrophotometric determination of trace amounts of sulfide ion

Abstract

The inhibitory effect of sulfide on the formation of blue ternary complex between silver, 1, 10-phenanthroline and bromopyrogallol red was applied to the spectrophotometric determination of 0 to 1.8μg of sulfide ion in 25 ml of final solution. The precision of the proposed method was within 4.4% (coefficient of variation). The molar extinction coefficient was 1.49×105 at 635 mμ. The recommended procedure was as follows: Fifteen millilitres of the silver complex solution (containing 30 μg silver per 15 ml) was taken into a 25 ml measuring flask, and a solution (less than 10 ml) containing 0 to 1.8μg of sulfide was added to it. It is then diluted to the mark with water, and after 10 minutes, the absorbance was measured against water at 635 mμ. Gold, cyanide, iodide and thiosulfate interfered even when their amounts were one fold of sulfide. Good results agreeing with those by p-phenylenediamine method (JIS K 0101) were obtained for the analysis of tap water mixed with known amounts of sulfide. © 1969, The Japan Society for Analytical Chemistry. All rights reserved.