Chromatographic Behavior of Cationic and Nonionic Surfactants on Silica Gel Impregnated with Paraffin Oil Using Aqueous Formamide Mobile Phase Systems

摘要

The migration behavior of cationic and nonionic surfactants on silica gel impregnated with paraffin oil, tertiary butyl phosphate and silicon oil using aqueous dimethyl formamide (DMF) was examined. The mobility of surfactants at different concentration levels of DMF in double distilled water was investigated on silica gel impregnated with 1 % paraffin oil. The most suitable mobile phase for the mutual separation of cationic and nonionic surfactants was the mixture of DMF and double distilled water in 6:4 ratios. The separation of cetylpyridinium chloride (CPC) from Brij-35 was successfully achieved on silica gel impregnated with 1% paraffin oil. The mobility pattern of cationic as well as nonionic surfactants on silica gel impregnated with (1, 3, 5, 7 and 10%) paraffin oil, 1% tertiary butyl phosphate and 1 % silicon oil was examined. The solvent effect on the R_F values of surfactants, with protic solvent (DMF and tetrahydrofuran i.e. THF) and aprotic (Dimethylsulfoxide i.e. DMSO) was performed on silica gel impregnated with 1 % paraffin oil. The migration behavior of surfactants on stationary phases (alumina, kieselguhr and cellulose) impregnated with 1 % paraffin oil was also studied. The results show reasonable reproducibility (R_F values differ by a factor of 10%). The limits of detection of CPC and BJ-35 were 0.73 and 0.75 ug respectively. To widen the applicability of the method, separation of CPC and BJ-35 from a sample of fabric softener was also investigated. The influence of metal cations as well as anionic impurities in the separation of CPC and Brij-35 was also examined.