A RAPID METHOD TO MEASURE EXOGENOUS GAMMA-HYDROXYBUTRIC ACID IN BEER FOR DRUG FACILITATED SEXUAL ASSAULT INVESTIGATION USING HYDROPHILIC INTERACTION LIQUID CHROMATOGRAPHY ELECTROSPRAY IONIZATION TANDEM MASS SPECTROMETRY

Abstract

Gamma-hydroxybutyric acid (GHB) is a drug of abuse with depressant effects that has been implicated in many cases of suspected surreptitious administration with purpose of increasing victim vulnerability to sexual assault because of its sedative and amnesic effects. Therefore, analytical methods for the identification and quantification of GHB are needed in forensic laboratories. In the current study, a novel rapid analytical method using hydrophilic interaction liquid chromatography electrospray ionization tandem mass spectrometry (HILIC-ESI/MS/MS) for the identification and quantification of the exogenous GHB in beer as one of the most available specimens encountered in forensic settings has been developed. The quantification of GHB in a beer sample was achieved using a SeQuant ZIC-HILIC analytical column (150 mm × 2.1 mm i.d., particle size 3.5µm). Under isocratic eluting conditions with a mobile phase consisting of 20% A (water/acetonitrile 80/20 + 1 mM ammonium formate) and 80% B (acetonitrile) at a flow rate of 0.30 mL/min, the analysis of each sample only took 2.5 min. The quantification of GHB was successfully achieved without interference from its structural isomers, i.e. alpha- hydroxybutyric acid (AHB) and beta-hydroxybutyric acid (BHB), due to baseline separation. The criteria for confirmation of identity set by the FDA for both high-resolution mass spectrometry (HRMS) and low-resolution mass spectrometry (LRMS) were successfully met. The method validation has met the ISO 17025 requirements with linear range from 1 to 50 µg/mL, precision of 8.64% relative standard deviation (RSD) or less, accuracy of 91.42 to 107.87%, limit of detection (LOD) of 0.01468 µg/mL, limit of quantitation (LOQ) of 0.0489 µg/mL, matrix effect with an average of 82.15%, and recovery of liquid-liquid extraction (LLE) with an average of 16.12%. Therefore, the developed analytical method was found to be rapid, sensitive, and accurate for the quantification of GHB in beer for drug facilitated sexual assault (DFSA) investigations.