Adduct supported analysis of γ-hydroxybutyrate in human serum with LC-MS/MS

Signal Separated Quantification of γ-Hydroxybutyrate With Liquid Chromatography-Tandem Mass Spectrometry in Human Urine and Serum as an Improvement of the Analyte Adduct Ion Based Quantification

The aim of the work was the development and validation of an LC-MS/MS γ-hydroxybutyrate (GHB) quantification method in urine and human serum by the use of the analyte adduct ion formation strategy. A combined detection with a conventional precursor ion in the negative electrospray mode and additionally GHB adduct ions with both sodium acetate and lithium acetate was in focus. Therefore GHB quantification based on separated MS/MS signals. Two tandem mass spectrometers representing different MS/MS generations (Sciex API 4000 QTrap and Sciex API 5500 QTrap) were used for method validation and comparison. Shimadzu HPLC Systems equipped with a Luna 5 µm C18 (2) 100 A, 150 mm × 2 mm analytical column were applied successfully for sample analyses. Infusion experiments were performed for adduct identification and analyte detection optimisation. Sample preparation could be limited to a simple and fast protein precipitation/sample dilution. An effective signal separated GHB quantification with three independent precursor ions representing separated areas of the mass spectrum was developed, validated according to forensic guidelines and applied in the routine. The developed and applied strategy resulted in a higher safety factor for the analyte quantification performed in the forensic toxicology. A relevant analytical improvement could be achieved with this alternative adduct based GHB analysis since a good correlation of analyte concentrations calculated on the basis of separated signals was stated as useful analytical information.

Simultaneous Quantification of γ-Hydroxybutyrate, γ-Butyrolactone, and 1,4-Butanediol in Four Kinds of Beverages

γ-Hydroxybutyrate (GHB) is a neurotransmitter, which exhibits a strong central nervous system depressant effect. The abuse of GHB or its precursor substances (γ-butyrolactone (GBL) and 1,4-butanediol (1,4-BD)) may cause serious problems. This study developed a fast and effective UHPLC-MS/MS method for the simultaneous quantification of GHB, GBL, and 1,4-BD in four popular beverages, including carbonated drinks, tea, apple cider vinegar, and coffee. The established method overcomes the influence of the in-source collision-induced dissociation of unstable compounds during quantification. The limits of detection were 0.2 μg/mL for GBL and 0.5 μg/mL for GHB and 1,4-BD with excellent linearity in the range of 0.2–50 μg/mL. The recoveries of the three compounds at three spiked levels (2.5, 5.0, and 10.0 μg/mL) in the four kinds of beverages studied were between 90 and 110%, while the relative standard deviations (RSDs) were all <10%. The matrix effect was negligible using this simple and appropriate preprocessed procedure. The method established in this study can quickly and reliably detect the GHB content and its analogues in beverages.

Screening and confirmation methods for GHB determination in biological fluids

The purpose of this review is to provide a comprehensive overview of reported methods for screening and confirmation of the low-molecular-weight compound and drug of abuse gamma-hydroxybutyric acid (GHB) in biological fluids. The polarity of the compound, its endogenous presence, its rapid metabolism after ingestion, and its instability during storage (de novo formation and interconversion between GHB and its lactone form gamma-butyrolactone) are challenges for the analyst and for interpretation of a positive result. First, possible screening procedures for GHB are discussed, including colorimetric, enzymatic, and chromatography-based procedures. Confirmation methods for clinical and forensic cases mostly involve gas chromatography (coupled to mass spectrometry), although liquid chromatography and capillary zone electrophoresis have also been used. Before injection, sample-preparation techniques include (a combination of) liquid-liquid, solid-phase, or headspace extraction, and chemical modification of the polar compound. Also simple "dilute-and-shoot" may be sufficient for urine or serum. Advantages, limitations, and trends are discussed.