Determination of sulfide at the parts-per-billion level by ion chromatography with electrochemical detection

An improved procedure for the determination of sulfide using ion chromatography with electrochemical detection has been developed. Detection limits have been extended down to 0.1 ng/mL, with linear response up to 1000 ng/mL. Several factors affecting the response of the system to sulfide have been investigated, including condition of the columns, the arrangement of the columns, purity of reagents, composition of eluent, conditions of the working electrode, stability of sulfide solutions, mechanism of retention, and temperature of the systems. The two mains sources of error in the determination of sulfide are impurities in the eluent and adsorption of sulfide on the columns. Metal impurities in the eluent and on the column must be removed to achieve sensitivities below 20 ng/mL. To accomplish this, a new column cleaning procedure has been developed and a rearrangement in the positioning of the columns is recommended.