Improved Sensitivity and Reduced Sample Size in Serum Fatty Acid Ethyl Ester Analysis

Abstract

Fatty acid ethyl esters (FAEEs) are nonoxidative esterification products of ethanol metabolism found after ingestion of ethanol (1). FAEEs were proposed as toxic mediators of ethanol-induced cell injury in a study of postmortem analysis of tissues and organs (2). Subsequently, direct damage to human hepatoblastoma cells by FAEEs was reported (3), as well as in vivo pancreatic injury in rats induced by FAEE infusion (4). FAEEs in serum are both short- and long-term markers of ethanol intake (5)(6). Because serum FAEE concentrations are useful indicators of ethanol intake, test sensitivity and sample volume have become increasingly important targets for improvement. The first use of gas chromatograph–mass spectrophotometry (GC-MS) detection systems for serum FAEE concentrations identified ethyl 16:0, ethyl 16:1, ethyl 18:0, ethyl 18:1, ethyl 18:2, and ethyl 20:4 (1). In these experiments, the FAEEs were isolated from an organic phase by thin-layer chromatography; individual species of FAEEs were then identified and quantified by GC-MS. The current procedure for isolation and quantification of FAEE using solid-phase extraction and GC-MS is based on a method developed by Bernhardt et al. (7). Improvements have increased the number of identifiable FAEEs in the current technique to include ethyl 14:0, ethyl 18:3n-3, ethyl 20:3n-6, ethyl 20:5n-3, and ethyl 22:6n-3. Preanalytical variables that affect FAEE quantification have been described in a recent report by Soderberg et al. (8). The standard procedure for FAEE analysis uses 1 …