Wipe-test and patch-test for alcohol misuse based on the concentration ratio of fatty acid ethyl esters and squalene CFAEE/ CSQ in skin surface lipids

Abstract

Fatty acid ethyl esters (FAEE) are known to be formed in blood and almost all human tissues after alcohol consumption and to be incorporated from sebum into hair where they can be used as long-term markers for excessive alcohol consumption. In order to examine whether skin surface lipids which consist mainly of sebum are an equally useful matrix for measurement of FAEE as alcohol abuse markers, samples were collected by a wipe-test from the forehead of 13 teetotallers, 16 social drinkers, 10 death cases with known recent alcohol misuse and five death cases without indications of alcohol misuse. The samples were analysed by headspace solid-phase microextraction and gas chromatography–mass spectrometry for ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate and by high performance liquid chromatography with photodiode array detector for squalene, (SQ), as a natural reference substance which the FAEE concentrations were related to. The ratio m FAEE/ m SQ ranged between 0.16 and 1.12 ng/μg (mean 0.34 ng/μg) for the teetotallers and between 0.08 and 0.94 ng/μg (mean 0.37 ng/μg) for the social drinkers with no significant difference between both groups. For the alcoholics 2.4–24.2 ng/μg (mean 13.1 ng/μg) were found. For two volunteers the course of m FAEE/ m SQ 2 weeks before and 3 weeks after a single high alcohol dose was pursued by daily wipe tests. A strong increase of m FAEE/ m SQ occurred between 7 and 12 days after the drinking event. This delay can be explained by the transition time of about 8 days between sebum production and its appearance on the skin surface known from literature. For seven social drinkers skin surface lipid samples were also collected using drug of abuse patches of the firm PharmCheck. The ratios m FAEE/ m SQ in these samples were in the same range as from the wipe-test. The comparison with the self-reported ethanol amounts consumed the week before and during the test gave no good correlation ( R 2 = 0.42). It can be concluded from the results that FAEE in skin surface lipids can be used for medium-term retrospective detection of heavy drinking.