Determination of trace inorganic anions in anionic surfactants by single-pump column-switching ion chromatography

An ion chromatography method has been proposed for the determination of three common inorganic anions (chloride, nitrate and sulfate) in anionic surfactants using a single pump system. The new system consists of an ion exclusion column, a concentrator column, and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph. The valves were switched several times for removing surfactants, concentrating and separating the three anions. The chromatographic conditions were optimized. Detection limits (S/N = 3) were in the range of 0.10–0.68 μg/L. The relative standard deviations (RSDs) of peak area were less than 4.6%. The recoveries were in the range of 84.1–112.6%.