A comparison of a commercial microdiffusion method and gas chromatography for ethanol analysis

A simple, rapid ethanol screen based on a microdiffusion technique (Toxi-Lab alcohol test) was evaluated using whole blood and urine samples and compared to a direct injection gas chromatographic technique. A total of 204 samples were analyzed, 124 whole blood specimens and 80 urine samples. The whole blood samples showed agreement in 79 of 80 samples that tested positive by gas chromatography. All 44 whole blood samples that tested negative by gas chromatography were also negative by the microdiffusion method. All urine samples, both positive and negative, as well as all control specimens showed agreement. The one whole blood sample that did not agree had an ethanol level by gas chromatography below the stated detection limit (0.01%) of the microdiffusion method. The microdiffusion method was found to be a viable screening test for the presence of ethanol in whole blood and urine. It is relatively inexpensive and rapid and is therefore an ideal method for screening samples before a more expensive or time-consuming confirmatory method.