Atomic Absorption Spectrophotometric Determination of Anionic Surfactants in Water

Abstract

A simple and sensitive method for the determination of anionic surfactant in water was established by using atomic absorption spectrophotometry with graphite furnace atomizer. The proposed method was based on the atomic absorption spectrometric determination of cobalt in a chelate complex produced by the reaction of anionic surfactant with bis [2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato] cobalt (III) chloride (Co-PADAP) proposed by Taguchi et al. A water sample (surfactant content <30μg) was taken in a beaker, adjusted to pH 1 with sulfuric acid and transferred into a separating funnel. One ml of 7.9×10-4M Co-PADAP solution was added to the sample solution and mixed for a few seconds. After allowed to stand for 1 min, 5.0 ml of benzene was added to the solution and shaked for 1 min. The benzene layer was subjected to atomic absorption spectrophotometry. The recoveries of sodium di-(2-ethylhexyl) sulphosuccinate as a standard compound added to various kinds of water were in the range of 92.0-110.0% and the coefficient variations were within 4.7%. The interference by ClO-could be eliminated by the addition of Na2SO3. There were high significant correlations between the proposed method and the methylene blue method or the Taguchi's colorimetric method. The assayed values of anionic surfactants in the water samples obtained from the rivers in Kobe city were distributed 0.026 mg/l and 2.562 mg/l.