We all know what Breathalyzers are, but few people know how they actually work.
A Breathalyzer analyzes a suspect’s breath sample to determine his or her % BAC, or blood alcohol content. The machine is a photometric color comparator that analyzes a 52.5 mL breath sample. Each compound has its own specific geometry. When a specific wavelength of light is passed through the sample, the instrument will measure how much light is transmitted through the compounds and how much is absorbed. This correlates directly to which compound is present and how much of it is in the sample.
Ethanol, the substance measured by the Breathalyzer, is analyzed well at 440 nanometers. By using the balanced chemical equation involving the breakdown of ethyl alcohol (ethanol) and some other nifty formulas, we can obtain important figures, including the amount of alcohol in a suspect’s bloodstream, BAC, and the number of drinks he or she had and how long ago they had them. This is clearly important when it comes to catching dangerous drunk drivers. Just a public service announcement: if you have a BAC of over .08 (around 3 beers for a man), do not drive. By doing this, you may save your or another’s life.