The individual was arrested in Washington for driving while intoxicated and provided breath samples in two different BAC Verifier Datamaster infrared breath alcohol instruments. The instruments recorded ethanol results ranging from 0.09 to 0.17, with corresponding interferant results of 0.02 to 0.06 over approximately 3 hours. Breath and venous blood specimens collected later were analyzed by gas chromatography and revealed an isopropanol level of 0.023, an acetone level of 0.057, and an ethanol level of 0.076. Qualitative analysis of the breath sample by gas chromatography/mass spectrometry also revealed the presence of all three compounds. This individual had apparently consumed both ethanol and isopropanol; acetone resulted from the metabolism of isopropanol. The breath test instruments detected the interfering substances on each breath sample, yet they did not reveal tendencies to report false interferences when compared with Statewide interferant data.