Examination of some performance characteristics of breath alcohol measurements obtained with the intoxilyzer 8000C following social drinking conditions.

The Intoxilyzer 8000C was used to measure breath alcohol concentration (BrAC) in 10 healthy subjects under social drinking conditions. Measurements commenced within 5 min of the end of drinking (EOD). For 14 blood-breath pairs, measured BrACs were compared to corresponding venous blood alcohol concentrations (vBAC) of samples drawn at least 30 min after EOD and within 5 min of the corresponding breath test. BAC was analyzed using an enzymatic method. Concentration differences between breath and blood (BrAC - vBAC) ranged from -32 to +3 mg/dL (untruncated BrAC) and from -32 to -4 mg/dL (truncated BrAC). The Invalid Sample message was actuated in five out of 23 BrAC profiles. In the remaining 18 samples, residual mouth alcohol was evaluated by comparing the maximum difference between successive (5 min apart) measurements (MID5) over 20-30 min after EOD with the precision of replicate BrAC values taken 30-40 min after EOD (5 mg/dL or less; precision unaffected by breath sample volume over the range of 2-3 L). MID5 values occurred within the first three measurements in 16/18 cases, indicative of a significant mouth alcohol effect. Thus, mandatory delays should be used with the Intoxilyzer 8000C prior to testing to minimize the probability of overestimation of BrAC due to mouth alcohol.