Use of a Glutamic Acid-containing Aqueous–organic Mobile Phase for On-plate Separation, Detection, and Identification of Cationic and Non-ionic Surfactants by Thin-layer Chromatography

A new thin-layer chromatographic system comprising silica gel G as stationary-phase and a three-component mobile phase, 0.1 M glutamic acid–methanol–acetone, 1:1:1 (v/v), has been found to be highly suitable for separation and identification of cationic and non-ionic surfactants. The experimental conditions were optimized to achieve differential migration of the surfactants. In addition to achieving separation of some important cationic and non-ionic surfactants on laboratory-prepared silica gel layers and on silica gel HPTLC plates, tetradecyltrimethylammonium bromide (TTAB) has been successfully separated from Triton X-100 (TX-100) in the presence of heavy metal cations. The method has been used for identification of TTAB and TX-100 in saline water, river water, and domestic waste water. Limits of detection were determined for TTAB and TX-100. TLC coupled with spectrophotometry was used for quantitative estimation of TTAB after preliminary separation from TX-100. The effects on separation of TTAB from TX-100 of sample pH, polarity of the alcohol in the mobile phase, nature of the amino acid in the mobile phase, and the presence of alumina, kieselguhr, or cellulose in the silica layer have also been examined.