The Effect of Prolonged Storage Time on the Stability of Fatty Acid Ethyl Esters in Hair Samples

The advantages of analysis of drugs in hair samples are recognized for the long window of detection, alongside easy sampling and long stability after sample collection. Alcohol markers, ethyl glucuronide (EtG) and total fatty acid ethyl esters (FAEEs) in hair, are widely used for monitoring alcohol consumption for clinical and forensic purposes. Although stability of drugs and EtG in hair samples is documented to a certain extent, stability of FAEEs in hair samples after collection has not been reported. This study covered hair samples that had been tested for FAEEs on the day of arrival at the laboratory and retested between 4 and 80 months later. The statistical analysis of the data set reveals significant lower FAEEs levels including ethyl palmitate (EtPa) ester levels when samples were retested for the second time after 6 days of storage under ideal conditions. Specifically, the results suggest that when measuring total FAEEs or solely EtPa in hair samples, the elapsed time between sample collection and analysis of the sample needs to be considered when interpreting the results. The recommendation is that whenever hair samples need to be tested for total FAEEs or EtPa, the analytical procedure needs to be performed within 1 week after collection in order to obtain meaningful results. The study results substantiate the case for the use of hair samples solely for the analysis of EtG, in conjunction with other measurements such as full blood count, carbohydrate-deficient transferrin test, liver function test or phosphatidylethanol alongside clinical assessment for a more effective evaluation of alcohol consumption.

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.

Detection of lawsone (2-hydroxy-1,4-naphthoquinone) in henna treated hair

Hair analysis plays an important role in abstinence control in forensic toxicology. However, hair coloration affects the concentrations of xenobiotics and may lead to false negative results. For instance, henna has been shown to decrease ethyl glucuronide concentrations in hair. For analysis of the main henna ingredient lawsone (2-hydroxy-1,4-naphthoquinone), hair samples were washed, cut into small pieces (less than 5 mm), incubated (20 mg) in water and with internal standard (theophylline) for 24 h at 37 °C. Lawsone was analyzed in the supernatant using liquid chromatography with diode array detection. For quantitative assay, the absorption at 280 nm was found to be linear up to 250 ng/mg hair. The detection limit of lawsone was 2.2 ng/mg, precision and accuracy were better than 6%. Lawsone was only detectable in 12 henna-colored hair samples in concentrations from 27.3 to 253.7 (median 92.6) ng/mg. The analysis of lawsone is recommended in cases of suspected hair coloration where assessment of oxidative treatment was negative (e.g. no increase of 1H-pyrrole-2,3,5-tricarboxylic acid (PTCA) and unobtrusive fluorescence microscopy).

Metabolomics of Pregnancy Complications: Emerging Application of Maternal Hair

In recent years, the study of metabolomics has begun to receive increasing international attention, especially as it pertains to medical research. This is due in part to the potential for discovery of new biomarkers in the metabolome and to a new understanding of the "exposome", which refers to the endogenous and exogenous compounds that reflect external exposures. Consequently, metabolomics research into pregnancy-related issues has increased. Biomarkers discovered through metabolomics may shed some light on the etiology of certain pregnancy-related complications and their adverse effects on future maternal health and infant development and improve current clinical management. The discoveries and methods used in these studies will be compiled and summarized within the following paper. A further focus of this paper is the use of hair as a biological sample, which is gaining increasing attention across diverse fields due to its noninvasive sampling method and the metabolome stability. Its significance in exposome studies will be considered in this review, as well as the potential to associate exposures with adverse pregnancy outcomes. Currently, hair has been used in only two metabolomics studies relating to fetal growth restriction (FGR) and gestational diabetes mellitus (GDM).

Influence of repeated permanent coloring and bleaching on ethyl glucuronide concentrations in hair from alcohol-dependent patients

BACKGROUND

Ethyl glucuronide (EtG), a minor metabolite of alcohol, is used as a sensitive marker in hair to detect the retrospective consumption of alcohol. The proximal 0-3 cm hair segment is often used for analysis, providing information on alcohol consumption over the past 3 months. Using more distal segments would allow the detection of alcohol consumption over longer time periods, thereby addressing the chronicity of the consumption. In view of this, permanent coloring and bleaching were shown in vitro to alter EtG concentrations in hair, but no in vivo studies are available to prove or disprove this.

AIMS

To investigate the influence of repeated bleaching and permanent coloring on EtG concentrations in vivo and to assess the stability of EtG concentrations in distal compared to proximal hair segments.

METHODS

Hair samples from alcohol-dependent patients with uncolored/unbleached (N=4), permanent coloration (N=5) and bleached hair (N=5) were analyzed in two to six 3 cm long segments for EtG concentrations, and alcohol consumption and hair cosmetic treatments were assessed.

RESULTS

We observed that hair bleaching and permanent coloring reduces EtG concentrations by 82±11% and 65±24%, respectively, with correlations between the number of cosmetic treatments and the decrease in EtG concentrations. EtG remained stable in untreated hair samples up to 18 cm.

CONCLUSIONS

EtG is a sensitive marker to assess chronic alcohol consumption up to 18 months in alcohol-dependent patients with no cosmetic hair treatments. However, in alcohol-dependent patients who color or bleach their hair, care should be taken when interpreting EtG measurements.

Ethyl glucuronide in hair - A highly effective test for the monitoring of alcohol consumption

In Germany drink driving offenders lose their license and must prove abstinence for one year in order to regain it. In this paper we assess the newly introduced ethyl glucuronide (EtG) tests in urine and hair in this alcohol abstinence monitoring. 20% (80 out of 386) of the 3cm long hair samples were tested positive for EtG in hair, compared to only 2% (92 out of 4248 samples) in urine in the same time period. Additionally 50% of the samples positive for EtG in hair had EtG values greater than 30pg/mg hair, indicating chronic alcohol consumption in the last three months. This study shows that four EtG tests in 3cm hair lengths reveal a significantly higher percentage of drink driving offenders who fail to be sober in the rehabilitation period, than do six random EtG tests in urine. Presumably, the hair test is more adequate to monitor long term alcohol abstinence than the urine test as defined by the new driving license re-granting medical and psychological assessment (MPA) in Germany.