Simultaneous inductively coupled argon plasma atomic emission spectrometer as a sulfur-specific detector for the HPLC analysis of sulfur-containing surfactants

Abstract

A method was developed for the analysis of sulfur-containing surfactant samples (alkylbenzenesulfonates, alkanesulfonates, alkyl sulfates, alkyl ether sulfates). The sulfur compounds were seperated by high pressure liquid chromatography (HPLC) on a 10 μm styrene-divinylbenzene column with methanol/0.05 M aqueous ammonium acetate (4:1 v v ) as the mobile phase. An ARL Model 34000 simultaneous inductively coupled argon plasma vacuum emission spectrometer (ICP) monitoring the 180.7 nm sulfur line served as the sulfur-specific detector. The analyses of the products from various manufacturers showed that the alkylbenzenesulfonates, the alkyl ether sulfates, and the alkyl sulfates contain many isomeric and homologous compounds that were not completely separated. Sulfate was a common contaminant in these samples. The 2 σ detection limits of the HPLC-ICP system for the sulfur-containing surfactants is approximately 15 ng sulfur corresponding to a solution with a sulfur concentration of 0.3 ng l under the experimental conditions used. The method is well suited for fingerprinting commercial sulfur-containing surfactants. Untreated wastewaters spiked with surfactants were analyzed without difficulties.