Potential of IRMS technology for tracing gamma-butyrolactone (GBL)

Popularity of γ-hydroxybutyric acid (GHB) is fairly stable among drug users, while the consumption of its chemical precursor, γ-butyrolactone (GBL), is a growing phenomenon. Although conventional analytical methods allow to detect this substance in various matrices, linking a trace and a source is still a difficult challenge. However, as several synthesis pathways and chemical precursors exist for the production of GBL, its carbon isotopic signature may vary extensively. For that purpose, a method has been developed to determine the carbon isotopes content of GBL by means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS).The δ13C-values of 19 bulk samples purchased worldwide were in the range from −23.1 to −45.8‰ (SD < 0.3‰). Furthermore, testing on the purification of GBL by distillation has not been found to be consistent with such a large range of δ13C-values, which are likely to result from the isotopic composition of the organic precursors used to produce GBL together with the kinetic isotope effect associated with the synthesis routes. Finally, inter- and intra-variability measurements of the δ13C-values demonstrated the high potential of IRMS for discriminating between seizures of GBL and for source determination.