This document outlines a method for analyzing total sulfide in water and water-suspended sediments. The method involves reacting sulfide ions with excess iodine in an acid solution. The remaining iodine is then titrated with sodium thiosulfate using starch as an indicator. The difference in titrant volume between a blank and a sample is used to calculate the sulfide concentration. Potential interferences include reducing substances and oxidants, which can contribute to errors. Precise reagents and procedures are described to standardize solutions and ensure accuracy of the iodometric titration method for quantifying total sulfide.