title: Detection of mouth alcohol during breath alcohol analysis.
abstract: The presence of mouth alcohol (MA) during alcohol breath test for law enforcement is the most common cause of falsely high breath alcohol concentrations (BrAC). A fast and reliable test for detection of MA roadside at the scene of the act would facilitate the police efforts for proper prosecution. A tentative technique to use orally exhaled water vapour as a reference gas to position the origin of alcohol was validated. BrAC and water vapour concentration (WVC) were simultaneously measured as a known MA component was added to subjects with existing blood alcohol. In the absence of MA, water always precedes alcohol in a volumetric expirogram. In the presence of MA this relationship reversed. A scatterplot of WVC versus BrAC from similar fractional exhaled volumes illustrates how their relative positions change by MA. A deviation area (DA) between the scatterplot curve and a fictitious linear relationship was defined as a measurement of MA. The accuracy and cut-off level of the DA to detect MA were determined with receiver operating characteristic (ROC) curve analysis. The area under the ROC curve (AUC) was 0.95 (95% CI 0.90-1.0), indicating excellent discriminatory ability. The optimal cut-off for DA to discriminate between MA ≥0.010 mg/L (1 μg/100 ml, 0.002 g/210 L) or lack of MA was -0.35, with a sensitivity of 0.91 and specificity of 0.95. Analysis of BrAC in relation to WVC is a practical method to detect and confirm MA contamination with high reliability.
authors: Lund University, Department of Clinical Sciences (Anaesthesia and Intensive Care, PICU), Skane University Hospital in Lund, SE-221 85 Lund, Sweden. Electronic address: lars.lindberg@med.lu.se.
authors: Lars
authors: L
authors: Lindberg
authors: Lund University, Department of Clinical Sciences (Anaesthesia and Intensive Care, PICU), Skane University Hospital in Lund, SE-221 85 Lund, Sweden.
authors: David
authors: D
authors: Grubb
authors: Servotek AB, Villa Fortuna, Sunnanåvägen 131, SE-232 91 Arlöv, Sweden.
authors: Daniel
authors: D
authors: Dencker
authors: Servotek AB, Villa Fortuna, Sunnanåvägen 131, SE-232 91 Arlöv, Sweden.
authors: Mikael
authors: M
authors: Finnhult
authors: Servotek AB, Villa Fortuna, Sunnanåvägen 131, SE-232 91 Arlöv, Sweden.
authors: Sven-Gunnar
authors: SG
authors: Olsson
mesh_terms: D000328:Adult; D000368:Aged; D001944:Breath Tests / Q000379:methods*; D000431:Ethanol / Q000032:analysis*; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results
chemical_list: D000431:Ethanol
keywords: Breath alcohol; Breath analysis; Ethanol; Forensics; Mouth alcohol; Water vapor