stearates and ethyl-glucuronide

Hair testing for alcohol biomarkers is an important tool for monitoring alcohol consumption. We propose two methods for assessing alcohol exposure through combined analysis of ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs) species (ethyl myristate, palmitate, stearate and oleate) in hair (30 mg). EtG was analysed by liquid chromatography-tandem mass spectrometry, while FAEEs were analysed by gas chromatography-tandem mass spectrometry using electron impact ionization. Both methods were validated according to internationally accepted guidelines. Linearity was proven between 3 and 500 pg/mg for EtG and 30-5000 pg/mg for FAEEs, and the limits of quantification were 3 pg/mg for EtG and 30 pg/mg for each of the four FAEEs. Precision and accuracy were considered adequate, processed EtG samples were found to be stable for up to 96 h left in the injector and processed FAEEs samples for up to 24 h. Matrix effects were not significant. Both methods were applied to the analysis of 15 authentic samples, using the cut-off values proposed by the Society of Hair Testing for interpretation. The results agreed well with the self-reported alcohol consumption in most cases, and demonstrated the suitability of the methods to be applied in routine analysis of alcohol biomarkers, allowing monitoring consumption using low sample amounts.

Topics: Adult; Alcohol Drinking; Biomarkers; Child, Preschool; Esters; Fatty Acids; Gas Chromatography-Mass Spectrometry; Glucuronates; Hair; Humans; Limit of Detection; Myristates; Oleic Acids; Palmitic Acids; Reproducibility of Results; Solid Phase Extraction; Stearates; Tandem Mass Spectrometry

Topics: Alcohol Abstinence; Alcoholism; Biomarkers; Chronic Disease; Consensus; Forensic Toxicology; Glucuronates; Hair; Hair Preparations; Humans; Myristates; Oleic Acids; Palmitic Acids; Stearates; Substance Abuse Detection

Fatty acid ethyl esters (FAEE), direct metabolites of ethanol, are suitable alcohol markers that can be detected in different tissues. The determination of FAEE in hair can help to evaluate social and excessive alcohol consumption. Due to the presence of FAEE in the hair of teetotalers, proving alcohol abstinence seems to be impossible. To verify these results, an solid phase micro extraction-gas chromatography/mass spectrometry procedure for the determination of the four FAEE: ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate in hair was validated with special focus on low concentration levels. Besides very high sensitivity (limits of detection between 0.005 and 0.009 ng/mg), good results for linearity, precision and accuracy, recovery and stability were achieved. In addition, 73 hair samples with measured ethyl glucuronide (EtG) concentrations between 4 and 10 pg/mg were analyzed for FAEE. By using the following cut-offs: EtG: 7 pg/mg, FAEE: 0.2 ng/mg a satisfying matching rate of 72.6% was found. This shows that FAEE can be determined to verify borderline EtG concentrations even in the context of abstinence tests. However, the diversified influencing factors on analyte concentrations in hair, which may explain the large deviations between EtG and FAEE results observed in some cases, have to be mentioned when interpret ambiguous results.

Topics: Alcohol Drinking; Fatty Acids; Gas Chromatography-Mass Spectrometry; Glucuronates; Hair; Humans; Limit of Detection; Myristates; Oleic Acids; Palmitic Acids; Reproducibility of Results; Solid Phase Microextraction; Stearates; Substance Abuse Detection

This article presents results from 47 meconium samples, which were analyzed for fatty acid ethyl esters (FAEE) and ethyl glucuronide (EtG) for detection of gestational alcohol consumption. A validated microwave assisted extraction (MAE) method in combination with GC-MS developed in the Institute of Forensic Science (Santiago de Compostela) was used for FAEE and the cumulative concentration of ethyl myristate, ethyl palmitate and ethyl stearate with a cut-off of 600ng/g was applied for interpretation. A simple method for identification and quantification of EtG has been evaluated by ultrasonication followed solid phase extraction (SPE). Successful validation parameters were obtained for both biochemical markers of alcohol intake. FAEE and EtG concentrations in meconium ranged between values lower than LOD and 32,892ng/g or 218ng/g respectively. We have analyzed FAEE and EtG in the same meconium aliquot, enabling comparison of the efficiency of gestational ethanol exposure detection. Certain agreement between the two biomarkers was found as they are both a very specific alcohol markers, making it a useful analysis for confirmation.

Topics: Adult; Alcoholism; Biomarkers; Calibration; Chromatography, Liquid; Esterification; Esters; Fatty Acids; Female; Gas Chromatography-Mass Spectrometry; Glucuronates; Humans; Infant, Newborn; Meconium; Microwaves; Myristates; Palmitic Acids; Predictive Value of Tests; Pregnancy; Pregnancy Complications; Reference Standards; Reproducibility of Results; Solid Phase Extraction; Stearates; Substance Abuse Detection; Tandem Mass Spectrometry