Simultaneous determination of GHB and EtG in hair using GCMS/MS.

A gas chromatographic tandem mass spectrometric (GCMS/MS) method for simultaneously determining trace concentrations of gamma-hydroxybutyrate (GHB) and ethyl glucuronide (EtG) in hair has been developed. Multiple reaction monitoring (MRM) was used to detect precursor and product ions of GHB, (233 and 147) and EtG (261 and 143) following anion exchange solid phase extraction and derivatization with N,O-bis[trimethylsilyl]trifluoroacetamide (BSTFA). Deuterated standards of GHB and EtG were used as internal standards. The assay produced excellent linearity (r(2) > 0.99) and sensitivity. The lower limit of quantitation (LLOQ) was 10 pg/mg for EtG assuming a 20 mg hair sample. The method has been used to investigate cases of suspected drug facilitated assault as well as being used to identify heavy alcohol consumption in a group of volunteers.