Micelle to solvent stacking of tricyclic psychiatric drugs in capillary electrophoresis

Abstract

A capillary electrophoresis (CE) method with UV-detection based on preconcentration with on-line micelle to solvent stacking (MSS) was optimized and validated to the simultaneous determination of tricyclic psychiatric drugs in urine samples. Sample preparation was based on liquid-liquid extraction (LLE) of analyzed drugs from biological samples. The electrophoretic conditions were: separation buffer composed of 40 mM sodium dihydrogen phosphate (pH 3.7) and 60% methanol (v/v), uncoated fused silica capillary (75 μm i.d.× 57 cm length), UV spectrophotometric detection at 254 nm, injection time 90 s at 3.45 kPa, applied voltage 25 kV, and temperature 22 °C. The advantage of proposed MSS strategy is its improved limit of detection of analytes compared to traditional CE technique. This is important for the analysis of drugs presented at very low concentration in biological samples. The developed CE method allows determination of psychotropic drugs at ng/ml level in human urine. This is the first report, presenting the possibility of determination of these drugs in urine samples by MSS-CE.