Simultaneous determination of nonionic and anionic industrial surfactants by liquid chromatography combined with evaporative light-scattering detection

LC/ELSD was used for the simultaneous and rapid analysis of various anionic and nonionic surfactants. Eight surfactants (APG, LAE7, CDE, NPE7, LAE9-cap, SLS, AOS, AOT) were separated within 30 min in one LC run on C18-bonded silica column with a methanol-water gradient condition, using ELSD detection. The ELSD could be used efficiently for the detection of the surfactants not detectable by UV absorbance. Calibration plots of peak area vs. injected mass were linear in the range of 0.4-140 microg injected per 20 microL, with a log-log slope of 1.4-2.4. Several commercial products were analyzed to demonstrate the practicality of the procedure.