DISPERSIVE LIQUID-LIQUID MICROEXTRACTION FOLLOWED BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AS AN EFFICIENT AND SENSITIVE TECHNIQUE FOR THE SIMULTANEOUS DETERMINATION OF ALPRAZOLAM, OXAZEPAM, AND DIAZEPAM IN HUMAN URINE SAMPLES

Abstract

Dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography was used for the extraction and determination of oxazepam, diazepam, and alprazolam in human urine. Dichloromethane and ethanol were used as extraction and dispersive solvents, respectively. The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability, and extraction solvent volume at µL level. The influence of several variables (e.g., type and volume of dispersant and extraction solvents, and ionic strength) on the performance of the sample preparation step has carefully evaluated. Under the optimum conditions, the enrichment factors 208, 218, and 226 for oxazepam, alprazolam, and diazepam, respectively, were obtained in urine samples. The calibration graphs were linear in the range of 1.0–500 µg L−1 for diazepam and 2.0–500 µg L−1 for oxazepam and alprazolam. The detection limits of 0.7 µ g L−1 for oxazepam and alprazolam and 0.3 µg L−1 for diazepam in urine samples were achieved. DLLME combined with HPLC-UV is a fast, simple, and efficient method for the determination of oxazepam, alprazolam, and diazepam in human urine.