The response of the Intoxilyzer 5000 to five potential interfering substances.
A study was conducted of potential vapor phase interferents which could be present on human breath and also be capable of inducing a false-positive response for ethanol on the evidential infrared-based breath testing device, the Intoxilyzer-5000. This involved preparation and validation of a range of vapor standards, which were introduced to the instrument using a dynamic flow double-bubbler system. Potential interferents were chosen on the basis of both their infrared signatures and their general availability, and included toluene, m-xylene, o-xylene, methanol and isopropanol. All compounds tested were found to be capable of inducing false-positive readings for ethanol in a highly reproducible manner, as a result of which it has been possible to derive precise least-squares equations describing the ethanol readout expected for any given blood concentration of toluene, m-xylene, o-xylene, methanol and isopropanol. The likelihood of an interference compromising the integrity of the analysis is related to both the toxicological significance and prevalence of a given blood concentration of each solvent, and the point at which the instrumental interference light is triggered in each case.
Caldwell
J P
JP
Department of Chemistry, University of Waikato, Hamilton, New Zealand.
Kim
N D
ND
D019840:2-Propanol / Q000032:analysis; D000438:Alcohols / Q000032:analysis*; D001555:Benzene Derivatives / Q000032:analysis*; D001944:Breath Tests / Q000295:instrumentation / Q000379:methods*; D000431:Ethanol / Q000032:analysis; D005189:False Positive Reactions; D005554:Forensic Medicine / Q000295:instrumentation*; D006801:Humans; D000432:Methanol / Q000032:analysis; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014050:Toluene / Q000032:analysis; D014992:Xylenes / Q000032:analysis
D000438:Alcohols; D001555:Benzene Derivatives; D014992:Xylenes; D014050:Toluene; D000431:Ethanol; D019840:2-Propanol; C031285:3-xylene; D000432:Methanol; C026114:2-xylene