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

EtG Quantification in Hair and Different Reference Cut-Offs in Relation to Various Pathologies: A Scoping Review

Ethyl glucuronide (EtG) is a non-volatile, non-oxidative, hydrophilic, and stable ethanol phase II metabolite. EtG is produced through ethanol glucuronidation by UDP-glucuronosyltransferase (UGT), a phase II enzyme. EtG can be extracted from different biological matrices, including keratin ones, such as hair or nails. The purpose of this scoping review is to describe the relationship between EtG levels in hair and some of the most common and frequent pathological conditions and verify whether different reference cut-offs in relation to various pathologies have been identified in the scientific literature. In fact, in-depth knowledge of the influence of pathologies, such as diabetes mellitus, hepatic and renal dysfunction, on EtG production and its storage in keratin matrices would allow a more appropriate interpretation of obtained data and rule out false positives or false negatives. This scoping review is based on bibliographic research carried out on PubMed regarding the quantification of EtG in hair of subjects affected by different pathological conditions. According to the scientific literature, the main and most common pathologies that can affect the concentration of EtG in hair are liver and kidney diseases and diabetes. The EtG quantification analytical data should be interpreted carefully as they may have a great impact in both forensic and clinical contexts.

Development and Validation of a GC-EI-MS/MS Method for Ethyl Glucuronide Quantification in Human Hair

Ethyl glucuronide (EtG) is a minor, non-oxidative ethanol metabolite detectable in several matrices for specific periods of time. In recent years, quantification of EtG in hair has been established as the most reliable biomarker for long-term alcohol consumption, with the Society of Hair Testing offering cut-off values for assessment of both abstinence and heavy drinking. Instrumental constrains and wide inter- and intra-laboratory variability represent the ultimate barriers to widespread acceptance of hair EtG determination in the forensic context. In this study, a new analytical method for hair EtG based on gas chromatographic (GC) separation, electron impact (EI) ionization, and tandem mass spectrometry (MS/MS) detection was developed and validated. At the same time, several parameters for sample pretreatment and instrumental analysis were optimized using real hair samples obtained from different drinking subjects. A full-factorial design-of-experiment approach included procedures for hair washing, pulverization, and extraction. Rigorous multi-step washing proved not to reduce the EtG content extracted in the subsequent sample incubation. Hair pulverization with a ball mill significantly improved the EtG extraction from the keratin matrix and allowed us to reduce the time needed for the subsequent extraction step, without affecting the extraction recovery. The hair extract was derivatized with N-methyl-N-(trimethylsilyl)-trifluoroacetamide. Upon electron impact ionization of the EtG-TMS derivative, triple quadrupole mass analyzers were operated in the selected reaction monitoring (SRM) mode using the fragment m/z 405 as the precursor ion (m/z 410 for the EtG-D5 internal standard), the transitions m/z 405 → 359 and m/z 410 → 359 for quantitation, and m/z 405 → 331 and m/z 405 → 287 for qualification/confirmation, all at 10 V collision energy. The final method was fully validated and then applied to 25 real hair samples. The calibration curve proved linear between 6 and 60 pg/mg. The limit of detection (LOD) was 4 pg/mg. Intra- and inter-assay precision and accuracy tests showed a variability and bias close to 15% or lower over the entire calibration range. The new method is routinely applied in the Italian State Police’s toxicology laboratory for hair analyses addressed to exclude excessive alcohol drinking and verify the psycho-physical requirements of the personnel.

Levels of GHB in hair after regular application

Gamma hydroxybutyrate (GHB) is a central nervous system depressant that is an approved drug for the treatment of narcolepsy with cataplexy and other syndromes. Due to its dose dependent stimulating, relaxing or sedative effects, illicit abuses include recreational use by young people and cases of drug-facilitated crime (DFC). Since GHB is also produced endogenously, for forensic questions, it is important to be able to differentiate between endogenous GHB and elevated levels due to additional intake. In this study, we measured GHB concentrations in hair of patients with narcolepsy receiving daily GHB treatment. The results were compared to endogenous concentrations and concentrations after chronic intake presented in several former studies. The aim of this study was to investigate whether a regular intake of a known dosage of GHB leads to elevated levels of GHB concentration in hair. We collected hair samples of 19 patients (14 female, 5 male) with narcolepsy under regular GHB treatment and examined the hair samples segmentally by digestion of the hair followed by liquid-liquid extraction and analysis using a Shimadzu LC20 UFLC system coupled with an AB Sciex API 4000 Qtrap tandem mass spectrometer. All volunteers received daily treatment with different doses of sodium oxybate (sodium salt of GHB) ranging between 3 and 9g per night. The observed mean value of GHB concentration in hair was 2.69ng GHB per mg hair for the 5 male participants, 1.56ng/mg for the 14 female participants giving an overall mean value of 1.86ng/mg for all participants. Our results showed no correlation between the daily dose or the duration intake of GHB and the measured concentration of GHB in hair. Although we did find a significant (p<0.01) difference between published endogenous levels of GHB in hair and GHB levels in hair of patients with regular daily GHB intake, the forensic relevance however is disputable. We hypothesise this narrow margin or even overlap to be the reason why analytical results from hair analysis in some cases fail to provide a reliable prove of a single exposition.

Detection of ɣ-hydroxybutyric acid (GHB) and ɣ-butyrolactone (GBL) in alcoholic beverages via total vaporization solid-phase microextraction (TV-SPME) and gas chromatography-mass spectrometry

Total Vaporization Solid-Phase Microextraction (TV-SPME) relies on the same technique as standard SPME but completely vaporizes a sample extract, and analytes are sorbed directly from the vapor phase. On-fiber derivatization may also be performed using TV-SPME, where the fiber is first exposed to the headspace of a vial containing the derivatization agent, then exposed to a new vial containing the sample. ɣ-Hydroxybutyric acid (GHB) and ɣ-butyrolactone (GBL) are drugs of concern in that they may be used in drug facilitated sexual assault by surreptitiously spiking them into a victim's beverage. These drugs cause sedation, memory loss, and are difficult to detect in biological samples. One challenge in their analysis is that they can interconvert in aqueous samples, which was demonstrated in samples allowed to stand at room temperature for long periods. A volume study of GBL in water was performed with volumes ranging from 1 to 10,000 µl to compare the efficacy of TV-SPME, headspace SPME, and immersion SPME. Lastly, water, beer, wine, liquor, and mixed drinks were spiked with either GHB or GBL with realistic concentrations (mg/ml) and microliter quantities were analyzed using a TV-SPME Gas Chromatography-Mass Spectrometry method. The GBL volume study demonstrated an increased sensitivity in GBL detection when TV-SPME was utilized. Additionally, GHB and GBL were identified in various beverages at realistic concentrations. Overall, TV-SPME is beneficial because it requires no sample preparation and uses smaller sample volumes than immersion and headspace SPME.

Determination of ethyl glucuronide in human hair samples: Decontamination vs extraction

Decontamination of samples prior to analysis is common practice and recommended for ethyl glucuronide (EtG) hair testing. The aim of this study was to evaluate the applied decontamination procedure during routine hair EtG analysis by monitoring the ethyl glucuronide concentrations in the washing solutions from a representative cohort of individual hair samples. Hair samples from 150 individuals were tested for hair EtG by a validated routine procedure (liquid chromatography/tandem mass spectrometry). A four-step decontamination procedure (ethanol, water, acetone, dichloromethane) was applied to all samples prior to analysis. Hair samples from 20 individuals were analyzed along with the complete set of individual washing solutions. Hair samples from an additional 130 individuals were analyzed along with the corresponding aqueous wash fraction only. No EtG was detected in the washing solutions from hair samples that tested negative for EtG (n = 42). Hair samples positive for ethyl glucuronide (n = 108) were found to liberate different amounts of EtG during decontamination: whereas no, or low portions of, EtG (< 10% of extracted hair EtG) were found in the corresponding washing solutions of the majority (n = 91) of individual samples, there was a minority of samples (n = 6) with more than half of the extracted hair EtG present in the decontamination solvent. No correlation of the decontaminated amount of EtG and the extracted hair EtG was observed. Further experimental studies are necessary to investigate if the observed easily removable fraction of EtG is associated with external contamination and if analysis of wash solutions could be helpful for identifying external contamination in hair testing for ethyl glucuronide.

Zwitterionic HILIC stationary phase as a valuable alternative in separative techniques: Application to the analysis of gamma-hydroxybutyric acid and its metabolite in hair

In this work, the physical and chemical properties of a novel zwitterionic LC stationary phase are applied to the development, validation and application of a new fast and reliable method devoted to the analysis of GHB (gamma-hydroxybutyric acid) and its relatively new discovered glucuronide metabolite in hair. The obtained sensitivity, expressed as limit of detection (LOD) and quantification (LOQ), were 0.033 and 0.10 ng/mg for GHB and 0.11 and 0.37 ng/mg, for GHB-glucuronide respectively. Linearity was assessed between LOQ and 50 ng/mg for both compounds. GHB and GHB-glucuronide extraction from hair matrix was maintained simple and consisted in an acidified-solvent incubation. No samples purification was required before LC-MS/MS analysis. The method was finally applied to 65 real hair sample, 60 adults and 5 children below 2 years old. The obtained results highlighted that GHB concentrations were in the range 0.11-0.96 ng/mg (average 0.38 ± 0.25 ng/mg) in 44 cases (68%) while in 21 samples GHB concentrations were in the range between LOD and LOQ (0.033-0.1 ng/mg). GHB-glucuronide was detected in few samples (n. 3) at levels below LOQ. The interest on these molecules relies on the fact that GHB is both a naturally occurring inhibitory neurotransmitter in the central nervous system and an illicit drug often experienced by victims of drug-facilitated sexual assault. GHB-glucuronide was firstly identified in urine by the group of Petersen in 2013 and, as per analogy to ethyl glucuronide, it was proposed as a longer biomarker for GHB intoxication.

Ethyl glucuronide hair testing: A review

Ethyl glucuronide (EtG) is a minor, non-oxidative ethanol metabolite that can be detected in several matrices (e.g. blood, urine, hair, meconium) for variable periods of time. Quantification of EtG in hair (hEtG) has established itself, over recent years, as one of the most reliable biomarkers of long-term alcohol consumption habits, with the Society of Hair Testing (SoHT) offering cut-off values for assessment of both abstinence and heavy drinking (>60 g/day). Despite its high diagnostic performance, however, issues concerning inter- and intra-laboratory variability as well as data interpretation are still being investigated and represent the ultimate barrier to widespread acceptance of hEtG in the forensic context. The aim of this review is to summarize currently available analytical methods of hEtG testing, provide a framework to understand current hEtG cut-offs and their possible upcoming changes (in particular, a lower abstinence cut-off has been proposed for the 2019 revision of the SoHT consensus), and offer a schematic but exhaustive overview of the pitfalls in result reproducibility and interpretation that may limit applications of hEtG testing in the forensic context. Ultimately, the purpose of the authors is not to undermine the reliability of hEtG as an alcohol use marker, but rather to enhance it by promoting familiarization with all aspects related to it, from ethanol pharmacokinetics and EtG incorporation into hair, to sample preparation and analytical methods, to specific cases warranting close attention and additional tests for correct interpretation of hEtG results.

Hair testing of GHB: an everlasting issue in forensic toxicology

BACKGROUND

In this paper, the authors present a critical review of different studies regarding hair testing of endogenous γ-hydroxybutyrate (GHB), concentrations in chronic users, and values measured after a single GHB exposure in drug facilitated sexual assault (DFSA) cases together with the role of a recently identified GHB metabolite, GHB-glucuronide.

CONTENT

The following databases (up to March 2017) PubMed, Scopus and Web of Science were used, searching the following key words: γ-hydroxybutyrate, GHB, GHB glucuronide, hair. The main key words "GHB" and "γ-hydroxybutyrate" were searched singularly and then associated individually to each of the other keywords.

SUMMARY

Of the 2304 sources found, only 20 were considered appropriate for the purpose of this paper. Summing up all the studies investigating endogenous GHB concentration in hair, a very broad concentration range from 0 to 12 ng/mg was found. In order to detect a single GHB dose in hair it is necessary to commonly wait 1 month for collecting hair and a segmental analysis of 3 or 5 mm fragments and the calculation of a ratio between the targeted segment and the others represent a reliable method to detect a single GHB intake considering that the ratios presently proposed vary from 3 and 10. The only two studies so far performed, investigating GHB-Glucuronide in hair, show that the latter does not seem to provide any diagnostic information regarding GHB exposure.

OUTLOOK

A practical operative protocol is proposed to be applied in all suspected cases of GHB-facilitated sexual assault (GHB-FSA).

Data on ethyl glucuronide and cocaethylene concentrations in the hair of cocaine users

We present data on ethyl glucuronide and cocaethylene concentrations from the hair of cocaine users. Head hair from 64 subjects, previously tested for cocaine, cocaethylene, benzoylecogonine and anhydroecgonine methyl ester (AEME), were subsequently analysed for Ethyl Glucuronide (EtG). Samples were prepared by solid phase extraction and analysed using gas chromatrography coupled to tandem mass spectrometry. The dataset is made available to allow analysis of possible correlation between cocaethylene and ethyl glucuronide or between other metabolites presented in the data.

Potential of GHB phase-II-metabolites to complement current approaches in GHB post administration detection

Recently, phase-II-metabolites of γ-hydroxybutyric acid (GHB), namely GHB-β-O-glucuronide and GHB-4-sulfate, were implemented in the scope of drug testing methods The clearance of GHB from the circulation is extremely fast due to its incorporation into the metabolic pathway of the citrate cycle. The elimination half-life of GHB from blood was reported to be dose dependent between 30 and 50min resulting in narrow detection windows of less than 12h after illicit administration or cases of drug facilitated sexual assault regardless of the biological matrix used. As sulfated metabolites tend to show prolonged half-lives and slower elimination kinetics compared to unmodified or glucuronidated drugs, the potential of GHB-4-sulfate in prolonging the detection of GHB administration was assessed. Its urinary concentrations were determined in n=100 samples from athletes and n=50 samples from sport students, and the resulting data were used to calculate a preliminary reference population-based threshold for urinary GHB-sulfate concentration. The threshold was then compared to concentrations found in post-administration urine samples collected from 3 volunteers who administered GHB within the setting of a clinical trial. Due to the large inter-individual variability of concentrations found in the reference population, GHB-4-sulfate itself was not suitable to prolong the detection times for GHB applications, even when specific gravity-corrected values were used. Therefore, a metabolomics-based approach was applied to the reference population samples and evaluated regarding other urinary metabolites that potentially correlate with the urinary excretion of GHB-4-sulfate and GHB-β-O-glucuronide in order to find a suitable marker to normalize urinary concentrations. The most promising candidate was found at a molecular mass of 321.0696 and was preliminarily identified as β-citryl-glutamic acid.

Bioanalytical procedures and developments in the determination of alcohol biomarkers in biological specimens

Excessive alcohol consumption is a global problem, and consequently its evaluation is of great clinical and forensic interest. Alcohol biomarkers have been the focus of several research works in the past decades, with new compounds being studied in more recent years. The main objective of this review is to discuss topics for an analyst to consider when evaluating alcohol consumption through the analysis of alcohol biomarkers in biological specimens. For this, existing alcohol biomarkers will be reviewed, including carbohydrate-deficient transferrin, 5-hydroxytryptophol, ethanol, hemoglobin-associated acetaldehyde, fatty acid ethyl esters, ethyl glucuronide, ethyl sulfate and phosphatidylethanol. Additionally, their potential will be discussed, as well as analytical considerations, main challenges, limitations, data interpretation and existing methodologies for their determination in biological specimens.

Hair ethyl glucuronide levels as a marker for alcohol use and abuse: a review of the current state of the art

BACKGROUND

Ethyl glucuronide (EtG) is a minor alcohol metabolite that has been proposed as a stable marker in hair to detect and quantify alcohol consumption over long time periods.

METHODS

We provide an outline of currently available techniques for EtG hair sample analysis and highlight the pitfalls related to data interpretation. The literature of EtG analysis has been reviewed from January 1980 up to August 2013. In addition, we present an overview of the clinical and forensic studies which have used EtG quantification in hair as a marker for alcohol consumption/abstinence and we provide suggestions for future research.

RESULTS

EtG is a stable marker in hair that can be used to detect and quantify alcohol consumption over long time periods. This alcohol metabolite remains in hair after complete elimination of alcohol. Currently, there are three main analytical techniques used to quantify EtG in hair: gas chromatography-mass spectrometry (GC-MS), gas chromatography-tandem mass spectrometry (GC-MS/MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). No standardized protocols are yet available for the analysis of EtG levels in hair samples, and the current protocols vary in sample preparation and extraction procedures. Variables such as hair length, cosmetic treatment, gender, and pathophysiological conditions influence the final results and should be taken into account.

CONCLUSIONS

EtG quantification in hair is a useful tool for the objective detection of alcohol consumption over extended time periods, but care should be taken when interpreting the results.

Application of mass spectrometry to hair analysis for forensic toxicological investigations

The increasing role of hair analysis in forensic toxicological investigations principally owes to recent improvements of mass spectrometric instrumentation. Research achievements during the last 6 years in this distinctive application area of analytical toxicology are reviewed. The earlier state of the art of hair analysis was comprehensively covered by a dedicated book (Kintz, 2007a. Analytical and practical aspects of drug testing in hair. Boca Raton: CRC Press and Taylor & Francis, 382 p) that represents key reference of the present overview. Whereas the traditional organization of analytical methods in forensic toxicology divided target substances into quite homogeneous groups of drugs, with similar structures and chemical properties, the current approach often takes advantage of the rapid expansion of multiclass and multiresidue analytical procedures; the latter is made possible by the fast operation and extreme sensitivity of modern mass spectrometers. This change in the strategy of toxicological analysis is reflected in the presentation of the recent literature material, which is mostly based on a fit-for-purpose logic. Thus, general screening of unknown substances is applied in diverse forensic contexts than drugs of abuse testing, and different instrumentation (triple quadrupoles, time-of-flight analyzers, linear and orbital traps) is utilized to optimally cope with the scope. Other key issues of modern toxicology, such as cost reduction and high sample throughput, are discussed with reference to procedural and instrumental alternatives.