Determination of γ‐hydroxybutyric acid in saliva by capillary electrophoresis coupled with contactless conductivity and indirect UV absorbance detectors

The aim of the current study was to optimise and validate the methodology for determination of γ‐hydroxybutyric acid (GHB) in saliva by CE combined with a contactless conductivity detector (C⁴D) and indirect UV absorbance detection (λ_ABS = 210 nm). The optimized BGE, consisting of 8.5 mM maleic acid, 17 mM arginine, 255 μM cetyltrimethylammonium bromide (CTAB), and 15% acetonitrile, was evaluated for the separation of GHB in saliva within 6 min. The performance characteristics of the CE‐C⁴D‐indirect UV methodology was validated. The instrument detection and quantification limits were 0.49 and 1.6 mg/L for C⁴D, and 5.1 mg/L and 17.0 mg/L for indirect UV, respectively. The linearity was obtained over the range from 2.5 to 400 mg/L for C⁴D and from 12.5 to 400 mg/L for indirect UV. The interday precisions were within 2.3–5.7% and intraday precisions were within 1.6–9.0% for C⁴D as well as 2.1–9.3%, 5.6–10.1% for indirect UV in spiked saliva, respectively. The recoveries were within 87.2–104.4%. The matrix effects were +53.2% for small concentrations up to 25 mg/L for C⁴D and +23.6% for concentrations up to 75 for mg/L for indirect UV detection. No matrix effects were observed for higher concentration levels. In conclusion, CE‐C4D‐indirect UV can offer a rapid, accurate, sensitive, and definitive method for the determination of GHB abuse in saliva samples as a forensic screening tool.