What does the message "invalid sample" indicate?

The message "invalid sample" signifies that the breath sample collected by the Intoxilyzer 8000 was compromised in some way. One common reason for this message is the presence of mouth alcohol or vomit. Mouth alcohol refers to alcohol that may be present in the oral cavity, rather than in the lungs, which can lead to inaccurate readings. If a subject has recently consumed alcohol or had any regurgitation, this can affect the breath test by contaminating the sample with alcohol that is not indicative of the blood alcohol concentration (BAC).

This indicates a need for the operator to ensure that the breath sample is representative of the subject's actual BAC. In cases where mouth alcohol is detected, the device cannot provide a valid measurement, hence the "invalid sample" indication.

Other causes of invalid samples include issues with the accuracy of the mouthpiece placement, which could also hinder the collection of a proper sample, but the specific mention of mouth alcohol or vomit is a direct indicator of contamination impacting the validity of the test.