Micellar electrokinetic chromatography with laser-induced fluorescence detection for rapid and sensitive analysis of two new bioactive reagents using dynamic covalent coating

A simple, rapid, selective, and sensitive micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence detection (LIF) method was developed, using hexamethyldisilazane (HMDS) as dynamic covalent coating (DCC), for the analysis of two new bioactive agents N-n-hexyl-N'-(sodium p-aminobenzenesulfonate) thiourea (HXPT) and N-n-undecyl-N'-(sodium p-aminobenzenesulfonate) thiourea (UPT) derivatized with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. MEKC methods both not using DCC and using DCC were investigated. In a series of optimization steps, DCC and a running buffer of 20 mM Na2B4O7 + 16 mM SDS + 8% acetonitrile were applied for determination of the derivatives. Linear relationships for HXPT and UPT were obtained in the range of 5 to 100 microM (correlation coefficient: 0.9986 for HXPT, 0.9978 for UPT), and the detection limits for HXPT and UPT were 16.5 and 39.0 ng mL(-1). The sensitivity was improved over that of fluorescence spectroscopy methods. The method was applied to the analysis of the two reagents in lab water waste with recoveries in the range of 95.6-107.5%.