Simultaneous determination of gamma-hydroxybutyric acid (GHB) and gamma-butyrolactone (GBL) in beverages

Importance of the topic

Gamma-hydroxybutyrate (GHB) and its prodrug gamma-butyrolactone (GBL) are central nervous system depressants frequently misused in drug-facilitated crimes and recreational settings. The legal distinction between non-controlled GBL and illicit GHB is critical since GBL converts to GHB both in vivo and in vitro. A reliable analytical method for distinguishing and quantifying these compounds in beverages is therefore essential for forensic and regulatory purposes.

Objectives and study overview

This study aims to develop a simple, rapid, and sensitive one-run ion chromatographic method to simultaneously determine GHB and GBL in alcoholic and non-alcoholic beverages. Key goals include achieving high linearity, minimal matrix effects, and the ability to monitor GHB–GBL interconversion.

Methodology and instrumentation

• Technique: Direct injection ion chromatography with UV spectrophotometric detection after chemical suppression with LiCl.
• Column setup: ProntoSil 120-5-C18 AQ Guard precolumn and Metrosep Organic Acids – 250 analytical column, maintained at 10 °C.
• Eluent: 0.5 mmol/L perchloric acid in ultrapure water; flow rate 0.45 mL/min; injection volume 20 µL; detection wavelength 205 nm.

Instrumentation used

• 850 Professional IC Anion – MCS system
• 863 Compact IC Autosampler
• Lambda 1010 UV/VIS Detector
• 771 Compact IC Interface

Main results and discussion

• Calibration linearity was excellent over 10–200 mg/L, with correlation coefficients of 0.9998 (GHB) and 0.9997 (GBL).
• Precision at midpoint concentration showed relative standard deviations of approximately 2.6% for GHB and 3.1% for GBL.
• Spiking experiments in diluted alcoholic cocktail (extra dry Martini with grapefruit juice) and various fruit juices revealed no significant matrix interferences.
• The method successfully traced GBL-to-GHB conversion: complete conversion under alkaline/blood-mimicking conditions and equilibrium formation under acidic conditions.

Benefits and practical applications

This one-run IC-UV technique offers a cost-effective, rapid alternative to GC–MS for forensic laboratories, enabling clear differentiation between GHB and its prodrug in diverse beverage matrices while satisfying legal requirements.

Future trends and potential applications

• Extension to other biological and environmental matrices.
• Integration with mass spectrometric detectors for enhanced specificity.
• Development of portable or field-deployable IC systems for on-site screening.

Conclusion

The described ion chromatographic method provides a robust, validated approach for simultaneous quantification of GHB and GBL in beverages, demonstrating high sensitivity, precision, and the capability to monitor prodrug interconversion. Its simplicity and compatibility with standard laboratory equipment make it well-suited for routine forensic analysis.

References

• Shearrow A., Huege K., Bogenschuetz G. Simultaneous determination of gamma-hydroxybutyric acid (GHB) and gamma-butyrolactone (GBL) in beverages. Metrohm application note 8.000.6057EN.