Analysis of Biofluids for Gamma-Hydroxybutyrate (GHB) and Gamma-Butyrolactone (GBL) by Headspace GC-FID and GC-MS

The past few years have seen a dramatic increase in the abuse of gamma-hydroxybutyrate (GHB) and gamma-butyrolactone (GBL) in the United States. The abuse stems primarily from their euphoric and sedative properties, but these substances are also misused by bodybuilders as steroid alternatives. Recently there has been an alarming increase in the use of GHB and GBL in crimes of drug-facilitated sexual assault. A rapid and sensitive procedure was developed for the analysis of biofluids containing GHB and GBL. Two separate aliquots of a biological specimen were spiked with an alpha-methylene-gamma-butyrolactone internal standard solution. One of the aliquots was treated with concentrated sulfuric acid for cyclization of GHB to GBL and the other remained untreated. Both aliquots were extracted with methylene chloride and concentrated. Extracts were screened using automated headspace gas chromatography-flame-ionization detection (GC-FID). Qualitative findings were quantitated and confirmed in a manner similar to the GC-FID procedure with some modifications. A calibrated solution of GHB-d6 (or GBL-d6, when warranted) was added to the aliquots at a concentration approximating the level determined by the GC-FID screen. The extraction was as described with conversion of GHB to GBL, but analysis was by full-scan gas chromatography-mass spectrometry (EI). Quantitation was performed by comparison of the area of the molecular ion of the parent drug (m/z 86) to that of the calibrated deuterated analogue (m/z 92). This analytical procedure allows for the rapid detection of GHB and GBL in biofluids. Its sensitivity has proven useful for the toxicological investigation of cases of drug-facilitated sexual assault.