Evaluation of the analytical performance of a fuel cell breath alcohol testing instrument: a seven-year comprehensive study.

Between 2003 and 2009, 54,255 breath test sequences were performed on 129 AlcoSensor IV-XL evidential instruments in Orange County, CA. The overall mean breath alcohol concentration and standard deviation from these tests was 0.141 ± 0.051 g/210 L. Of these test sequences, 38,580 successfully resulted in two valid breath alcohol results, with 97.5% of these results agreeing within ±0.020 g/210 L of each other and 86.3% within ±0.010 g/210 L. The mean absolute difference between duplicate tests was 0.006 g/210 L with a median of 0.004 g/210 L. Of the 2.5% of duplicate test results that did not agree within ±0.020 g/210 L, 95% of these had a breath alcohol concentration of 0.10 g/210 L or greater and 77% had an alcohol concentration of 0.15 g/210 L or greater. The data indicate that the AlcoSensor IV-XL can measure a breath sample for alcohol concentration with adequate precision even amid the effects of biological variations.