Detection and quantification of etomidate and metomidate in human hairs by ultraperformance liquid chromatography with triple quadrupole mass spectrometry (UPLC-MS/MS).

Purpose: Intravenous narcotic agents, such as etomidate and metomidate, has been widely spread and abused in the world, including in Korea and China; thus, it is important to establish validated and sensitive analytical method for these compounds. Human hair as a biological sample has various advantages, including a wide detection window of drugs, compared to other typical samples, such as urine and blood in investigation. The purpose of this communication is to develop a reliable and useful method for the simultaneous detection and quantification of etomidate and metomidate in human hair samples by ultraperformance liquid chromatography combined with triple quadrupole mass spectrometry (UPLC-MS/MS), and to apply it for authentic samples in abuse cases.

Methods: The hair samples were washed with a detergent solution, followed by with water and acetone. After drying, they were cut into approximately 2 mm sections and then ground to powder by a low-temperature grinder. The 20 mg of hair powder plus internal standard in 1 mL of methanol was vortexed and then centrifuged to obtain the supernatant layer, followed by subjecting to analysis.

Results: The coefficient of determination (r²) values of the calibration curves of etomidate and metomidate in the hair samples were both more than 0.99 in the range of 1-500 ng/mg and 1-500 pg/mg, respectively. The limits of detection and lower limits of quantification were 0.5 and 1 pg/mg, respectively, for the both target compounds. Other tested validation data were all satisfactory. Etomidate and metomidate could be detected in the all hair samples and cigarette oil, which were seized by the police. The concentrations of etomidate and metomidate obtained from 10 samples from suspects were 5.48-45.7 ng/mg and 3.60-377 pg/mg, respectively. The concentrations of etomidate and metomidate in the cigarette oil were 95.8 μg/mg and 2.8 μg/mg, respectively.

Conclusions: In this study, a simple and reliable analytical method for etomidate and metomidate in the human hair has been established. To the best of our knowledge, this is the first report to establish a method for the simultaneous detection and quantification of etomidate and metomidate in the human hair, and to apply it to authentic samples seized in authentic cases.