Bossers, Lydia C. A. M.

English

It can be useful to discover a person’s chronic drinking consumption in child custody cases and to aid in the diagnosis of diseases like fetal alcohol spectrum disorder. When one alcohol marker in hair is analysed to indicate chronic use false negatives and false positives can occur. When two (ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs)) are analysed false negatives and false positives can be recognized and provide stronger evidence as is underlined statistically in this work. For a combined method, the sample preparation and analytical procedures were optimized. The effect of the decontamination step was difficult to interpret, which shows that addressing issues with external contamination is challenging. Analytes may be extracted from the hair matrix during decontamination and analytes can diffuse into the hair shaft from external contamination. The last is illustrated by the incorporation via excretions of endogenous EtG and FAEEs. A novel and sensitive analytical procedure was developed and validated which saves time and possibly money compared to analysing of both markers separately. The best overall method had a linear calibration curve (r2 &gt; 0:99) and an intra-day (n=3) and inter-day (n=9) accuracy for the quality control samples at three concentration levels between 84–118% with a coefficient of variation of 3–30% for both EtG and the FAEEs. The Bayesian approach was suggested as a new interpretation framework for hair tests, to account for the uncertainties in these tests in a transparent manner. In this work databases were constructed with EtG and FAEEs hair concentrations linked to the subject’s chronic alcohol use, the likelihood ratios were calculated and working examples were provided. This showed that a positive hair test for either EtG or FAEEs may very well be only ’limited’ evidence and therefore should only be used with a high prior odds. This means that a hair test result should not be used in isolation. The large confidence interval in this study also underlines the need for more control data

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Alcohol markers in hair: New detection techniques and evidence interpretation

https://pure.southwales.ac.uk/files/1622837/FinalThesisLydiaBossersNEW.pdf

Alcohol markers in hair: New detection techniques and evidence interpretation

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