Separation of stilbenes by capillary electrophoresis and high-performance liquid chromatography

Stilbenes, fluorescence whitening agents (FWAs), are usually added to clean ing agents in household and in industry. Capillary electrophoresis (CE) was often applied to separate various compounds simultaneously for its multino mial advantages. In this paper, we established analytical methods of six di aminostilbenes with CE and ion-pair chromatography (IPC). The optimum mobil e phase for IPC was 11.78 mM tetrabutylammonium hydrogen sulfate (TBA) aque ous and acetonitrile. An IPC method has been developed for simple and direc t separation for diaminostilbenes, anionic substances, with TBA as ion-pair reagent. Satisfactory linear ranges (7.0 x 10(-3) similar to 3.0 x 10 mug/ mL), correlation coefficients (0.9992-0.9999), and detection limits (6-13 n g/mL) were obtained. Separations were also performed by capillary zone elec trophoresis (CZE) using a buffer consisting of Tris (pH 10.1), n-tetradecyl trimethylammonium bromide (TTAB) and acetonitrile. A linear range of 5.0 x 10(-1)-4.0 x 10 mug/mL, correlation coefficients between 0.9975 and 0.9998, and detection limits between 337 and 446 ng/mL were obtained. In particula r, the separation of a pair of similar compounds (mass difference of 2) was achieved by addition of TTAB. The optimum analytical methods of CE and hig h-performance liquid chromatography (HPLC) were applied to commercial house hold with direct analysis and standard addition. No significant bias were s hown between them by t-test at 95% confidence level.