In order to understand the basic principles behind the operation of the alcohol breath analyzer, one needs familiarity with both biological and chemical facts. But in order to appreciate the importance of the alcohol breath analyzer, one does not need any science training. More than fifty years ago, the analyzer satisfied a pressing need. It was a pressing need that was recognized by many police who were out watching the drivers on the road. It was a need that was met by one inventive police officer in the state of Indiana. Read here about who he was and what he invented.
Each state in the United States has a law stipulating the maximum allowed blood alcohol content for someone seated at the wheel of a motored vehicle. In some states that maximum is 0.1%, and in other states it is 0.08%. Yet the methods that would allow law enforcement officers to monitor compliance with those stipulations did not always include a check that could be performed out in the “field.”
In fact, until 1954 law enforcement officers had to rely on a set of roadside sobriety tests. Until Dr. Robert Berkenstein had invented the first alcohol breath analyzer police could subject a suspected drunk driver to only two unrefined examinations—an order to the suspect to touch his or her nose, and a request that the same suspect walk in a straight line.
Dr. Berkenstein, a member of the Indiana State Police, recognized his ability to answer a need by making use of known facts about alcohol. He realized that he could utilize the manner by which the body admits alcohol into the circulatory system. His observations and inventive skills produced a prototype of the present-day alcohol breath analyzer.
Exactly what observations led to the creation of the alcohol breath analyzer? They were observations made by many of the police who patrolled the roads of the U.S. Dr. Berkenstein noted that after someone drinks a beverage containing alcohol, then that drug has a rapid effect upon the drinker’s body. That rapidity is evidence of the fact that alcohol is absorbed in the stomach; it does not pass through the rest of the digestive tract.
Dr. Berkenstein also noted that alcohol is a very volatile substance, i.e. it dissolves quickly. That fact suggested that alcohol in the blood would easily evaporate from the blood. That fact pointed to the set of conditions that could be used for creation of an alcohol breath analyzer.
So, how do alcohol breath analyzers work? Alcohol from the blood evaporates into the air in the lungs. That alcohol-filled air is then exhaled. If the person exhaling that air is a drunken driver, then he or she can be asked to breathe into an alcohol breath analyzer. That is a device that offers quite definitive proof concerning the sobriety, or lack of sobriety, for any tested individual.
In the analyzer, the exhaled air passes through a mixture of sulfuric acid, potassium dichromate, silver nitrate and water. The silver nitrate catalyzes a chemical reaction. That reaction leads to production of chromium sulfate, potassium sulfate, acetic acid and water. The silver nitrate, the catalyst, remains unchanged.
The chromium sulfate has a distinctly green color. The intensity of that green color can be used to gage the amount of alcohol in the exhaled air. The amount of alcohol in the exhaled air is proportional to the blood alcohol content of the tested driver. That explains why the alcohol breath analyzer has the ability to assess a driver’s sobriety.