Analysis of multiple abused drugs and hypnotics in urine by sweeping CE

Multiple drugs usage is very common in addicts (AD). However, some parent drugs were undetectable in urine, it was necessary to monitor their metabolites simultaneously. A sweeping CE was established for the determination of several kinds of abused drug and their metabolites in AD urine. This method was developed using chemometric experimental design to simplify the CF optimization. The capillary was filled by separation buffer (phosphate buffer (75 mM, pH 2.5) and methanol (70:30 v/v)) and then hydro-dynamically injected large volume of samples into capillary (1 psi, 200 s). Following was using sweeping buffer (phosphate buffer (75 mM, pH 2.5) and methanol (90:10 v/v) containing 65 mM SDS) to sweep and stack analytes. The separation voltage was set at -15 kV (anode at detector end). During method validation, calibration plots were linear (r >= 0.992) over a range of 0.1-3 mu g/mL for codeine, ketamine, and methamphetamine, 0.15-3 mu g/mL for morphine, 0.1-1 mu g/mL for alprazolam and oxazepam, and 0.1-1.2 mu g/mL for other other benzodiazepines and its metabolites. During intra- and inter-day analysis, relative standards and relative errors were less than 14%. The analytes could be simultaneously analyzed and have a detection limit down to 20-50 ng/mL (S/N = 3). The results showed good coincidence with GC-MS or LC-ESI-MS. This method was feasible for application to detect trace levels of abused drugs in AD' urine.