Determination of γ-hydroxybutyrate (GHB), β-hydroxybutyrate (BHB), pregabalin, 1,4-butane-diol (1,4BD) and γ-butyrolactone (GBL) in whole blood and urine samples by UPLC-MSMS

Methods for urine drug testing using one-step dilution and direct injection in combination with LC–MS/MS and LC–HRMS

The advent of LC combined with MS made it possible to design analytical methods for urine drug testing based on the very simple concept of diluting urine with an internal standard as the sole preparation procedure prior to instrumental analysis. The number of publications using this method design increased after the development of high-efficiency LC based on sub-2 μm particles. The success of this method design for drug testing, doping control and toxicological investigations of urine is now well documented and comprise both screening and confirmation methods. The nondiscriminating nature of this method design makes it even more attractive in combination with high-resolution MS for multicomponent target and general unknown analysis applications.

A surrogate analyte-based LC-MS/MS method for the determination of γ-hydroxybutyrate (GHB) in human urine and variation of endogenous urinary concentrations of GHB

γ-Hydroxybutyrate (GHB) is a drug of abuse with a strong anesthetic effect; however, proving its ingestion through the quantification of GHB in biological specimens is not straightforward due to the endogenous presence of GHB in human blood, urine, saliva, etc. In the present study, a surrogate analyte approach was applied to accurate quantitative determination of GHB in human urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to overcome this issue. For this, (2)H6-GHB and (13)C2-dl-3-hydroxybutyrate were used as a surrogate standard and as an internal standard, respectively, and parallelism between the surrogate analyte approach and standard addition was investigated at the initial step. The validation results proved the method to be selective, accurate, and precise, with acceptable linearity within calibration ranges (0.1-1μg/ml). The limit of detection and the limit of quantification of (2)H6-GHB were 0.05 and 0.1μg/ml, respectively. No significant variations were observed among urine matrices from different sources. The stability of (2)H6-GHB was satisfactory under sample storage and in-process conditions. However, in vitro production of endogenous GHB was observed when the urine sample was kept under the in-process condition for 4h and under the storage conditions of 4 and -20°C. In order to facilitate the practical interpretation of urinary GHB, endogenous GHB was accurately measured in urine samples from 79 healthy volunteers using the surrogate analyte-based LC-MS/MS method developed in the present study. The unadjusted and creatinine-adjusted GHB concentrations in 74 urine samples with quantitative results ranged from 0.09 to 1.8μg/ml and from 4.5 to 530μg/mmol creatinine, respectively. No significant correlation was observed between the unadjusted and creatinine-adjusted GHB concentrations. The urinary endogenous GHB concentrations were affected by gender and age while they were not significantly influenced by habitual smoking, alcohol drinking, or caffeine-containing beverage drinking.

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.

Prevalence of synthetic cannabinoids in blood samples from Norwegian drivers suspected of impaired driving during a seven weeks period

From early year 2000 different herbal products containing synthetic cannabinoids (SC) have appeared on the drug market all over the world, and new substances are frequently introduced. The prevalence of SC use in different populations is however still mainly unknown, also in Norway. This information is difficult to obtain, but studies of drivers suspected of driving under the influence of drugs (DUID), might provide important information. The aim of this study was to assess the prevalence of SC in drivers suspected of being under the influence of drugs in Norway, and investigate if SCs impair driving performance. For two periods of three and four weeks all blood samples from drivers suspected of DUID in Norway were analyzed for the presence of 12 and 18 different SCs, respectively. A new ultra performance liquid chromatography tandem mass spectrometry method was developed. A total of 726 cases were analyzed during our study period, and SCs were detected in 16 cases (2.2%) in total. The mean age of these drivers was 29.6 years. High concentrations of other psychoactive drugs were detected in all the blood samples where a SC was found. AM-2201 and JWH-018 were the most frequently detected SCs, each found in five cases. In addition RSC-4, JWH-122, JWH-081 and JWH-250 were detected. None of the drivers had reported using SCs prior to driving. Despite the limited number of SCs investigated in this 7 week study period, a considerable percent of the cases were positive. Other psychoactive drugs of abuse were always found concomitant with the SCs, and the age of these drivers indicates that experienced drug users also ingest SCs. Since other drugs were found in all the samples, the psychomotor impairment caused by the SCs is difficult to estimate. Our study shows the importance of screening analyses of biological samples from different populations to assess the prevalence of drug use, since self-reporting might be encumbered with significant under-reporting.

Simultaneous determination of β-hydroxybutyrate and β-hydroxy-β-methylbutyrate in human whole blood using hydrophilic interaction liquid chromatography electrospray tandem mass spectrometry

OBJECTIVES

For the quantification of β-hydroxybutyrate (BHB) and β-hydroxy-β-methylbutyrate (HMB) in human whole blood, a method using hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) was developed, which does not require chemical modification of the analytes.

DESIGN AND METHODS

Samples were deproteinised by a mixture of methanol and acetonitrile, and the extracts were cleaned-up using both polymeric strong cation exchange and strong anion exchange sorbents. The analytes and their structural isomers were separated using a column with a zwitterionic stationary phase. Isotope dilution of both analytes was used for quantitative analysis.

RESULTS

Separation of BHB from isobaric interferences was achieved through chromatography. The relative intra-laboratory reproducibility standard deviations were better than 10% for blood samples at concentration levels of 10-20μM BHB and 1μM HMB and better than 5% at concentration levels 10 times higher. The mean true extraction recoveries were close to 100%. The trueness expressed as the relative bias of test results was within ±5% at concentration levels of 10-1000μM BHB and 1-20μM HMB. The lower limits of quantification were estimated to be 3μM for BHB and 0.4μM for HMB.

CONCLUSIONS

A simple and highly sensitive and selective HILIC-MS/MS method was developed that is suitable for the quantification of BHB and HMB in whole blood.