Measuring BAC is Trickly and Complicated
According to an article posted on howstuffworks.com, law enforcement officers rely on a variety of tactics and devices to reasonably determine whether or not a person is under the influence of drugs or alcohol. Some of the most effective methods of this determination involve devices used to measure blood alcohol concentration (BAC) level. Breathalyzers, Intoxilyzers, and Alcosensor III or IV are the three major devices that are used to determine BAC levels.
Breathalyzers are the most commonly talked about type of test. This type of test relies on a chemical reaction involving alcohol to determine whether or not a person has a BAC above the legal limit. During the test, a person blows into a device. A silver nitrate catalyst then separates alcohol traces from one’s breath, and that alcohol then interacts with reddish-brown potassium dichromate to form a green chromium ion, an indication that alcohol is indeed present in the system of the person being tested. The substance is then compared against a sample ion, an indicator needle is activated, and the person’s BAC is determined according to how much the person administering the test needs to turn a dial in order to correct the needle.
Intoxilyzers use infrared light to affect the vibrations of molecules. Based on the change in vibration of the molecule, it can be determined whether or not, as well as how much, ethanol is present to help determine toxicity level. With this device, BAC level is ultimately determined according to how much infrared light is absorbed by the molecules.
