Determination of gamma-hydroxybutyrate in water and human urine by solid phase microextraction-gas chromatography/quadrupole ion trap spectrometry

A simple method of detection was developed for gamma-hydroxybutyrate (GHB). The method involves the derivatization of GHB using a hexyl-chloroformate procedure in aqueous media (such as water or urine), extraction of the deri vatization product directly from the sample using solid-phase microextracti on, and subsequent separation and detection with gas chromatography quadrup ole ion trap mass spectrometry. The deuterated form of GHB (GHB-D-6) is use d as an internal standard for quantitation. The method was linear for GHB-s piked pure water samples from 2 to 150 mug/mL GHB with a detection limit of 0.2 mug/mL. Spiked urine samples showed linearity from 5 to 500 mug/mL GHB with a detection limit of 2 mug/mL. The SPME-GC/MS method is applied to ac tual case samples, and the results are compared to those values obtained us ing a conventional GC/MS method. Sensitivity and linearity are comparable t o those seen using traditional methods of separation, yet the SPME method i s superior due to the simplicity, speed of analysis, reduction in solvent w aste, and ability to differentiate between GHB and gamma-butyrolactone (GBL ).