The trapping, storing, and subsequent analysis of ethanol in in-vitro samples previously analyzed by a nondestructive...

There is a need for a simple technique to collect breath samples of persons suspected of driving under the influence of alcohol. Solutions containing ethanol were analyzed using dichromatic oxidation procedures. The standard solutions were placed in a breath alcohol simulator at 34 degrees C and the vapors analyzed with a CMI Intoxilyzer, Model 4011AS, with one-way valves placed at either end to prevent air entering the outlet or leaving through the inlet. The analyzed 715-mL vapor sample was then pumped through an activated silica gel column. The trapped alcohol was removed from the column with water, and the resulting solution was analyzed by dichromate oxidation, liquid injection, and headspace gas chromatographic procedures. A very good linear relationship between concentration and peak height ratio was obtained by gas chromatography. The slope of the graph was used to calculate the percentage of blood alcohol for breath samples previously analyzed by the Intoxilyzer. The average deviation from the correct alcohol value was +/- 5%. Samples were collected, stored, and analyzed after 15, 90, and 120 days with no apparent loss of alcohol. The three methods of analyzing the trapped alcohol were compared. Over 100 trapped samples were collected in the field and analyzed, and the laboratory analyses were compared with the breath analyzer printouts.