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Direct measurement of alcohol and its metabolites


Robert Swift MD, PhD
Professor of Psychiatry and Human Behavior
Associate Chief of Staff for Research and
VA Medical Center
Providence VA Medical Center
Research 151
830 Chalkstone Avenue
RI 02908
Tel: (401) 457 3066
Fax: (401) 457 3305


Background  Ethanol can be easily and accurately measured in body fluids or vapours by several chemical and enzymatic methods. However, the persistence of ethanol in the body is short lived and ethanol's metabolism and distribution within the body are extremely complex.

Aim  This article discusses the complex pharmacokinetics of ethanol and how pharmacokinetics can affect measured ethanol concentrations when ethanol is sampled across different individuals or from different body fluids or vapors, such as whole blood, plasma, breath, urine, saliva, or transdermal ethanol.

Findings  Several physical methods for the quantification of ethanol concentrations are described, including gas chromatography, electrochemical detection, infrared detection and enzymatic methods, along with their advantages and limitations. Also discussed, is the utility of the measurement of several immediate metabolites of ethanol, including acetaldehyde, acetate, and fatty acid ethyl esters.

Conclusions  The complex distribution and metabolism of ethanol and its metabolites can obscure the relationship between the ethanol concentration that is measured in body fluids or vapours and the amount of ethanol that is actually taken into the body.