Simultaneous determination of free methamphetamine, pethidine, ketamine and tramadol in urine by dispersive liquid-liquid microextraction combined with GC-MS.

A simple and rapid dispersive liquid-liquid microextraction (DLLME) technique coupled with gas chromatography-ion trap mass spectrometry (GC-MS) was developed for the extraction and analysis of methamphetamine (MA), pethidine (PD), ketamine (KT) and tramadol (TD) from human urine. In this study, different parameters affecting the extraction process such as the type and volume of extraction solvent, type and volume of disperser solvent, extraction time and pH value and salt effect were studied and optimized. Under optimized conditions, the enrichment factor ranged from 185 to 226 and the average recovery ranged from 80.45% to 95.55%. The linear range was 10.0-1000.0 µg/L, the limit of detection and quantitation were in the range 0.43-1.96 µg/L and 1.44-6.53 µg/L, respectively. The relative standard deviations were in the range 1.98%-3.90% ( = 7). The obtained results show that DLLME combined with GC-MS is a fast and simple method for the determination of MA, PD, KT and TD in human urine.