Test for a Primary Alcohol Potassium Dichromate

Updated April 17, 2017

Potassium dichromate is the active ingredient in a breathalyzer. Alcohol exhaled into the breathalyzer initiates a chemical reaction that indicates the amount of alcohol in the breath, therefore in the blood. Alcohol in the breath turns the red-orange potassium dichromate in the breathalyzer yellow, blue or green, depending on the amount of alcohol. The potassium dichromate breathalyzer test is as accurate as blood and urine tests in determining blood alcohol content.


The Substance Abuse and Mental Health Services Administration facilities use both urine tests and breathalyzers to determine alcohol content in the blood. SAMHSA has tested and reports no significant difference in the accuracy of the breathalyzer used by 58 per cent of its facilities and the urine tests of blood alcohol concentration used by 83 per cent of its facilities. The "Journal of Biological Chemistry" compared blood, breath and urine tests of alcohol content in the blood and found no significant difference in the results. The "Journal of Biological Chemistry" reports that potassium dichromate has a stable colour that makes it an accurate indicator in its reduction reaction with alcohol.

Blood Alcohol

Alcohol enters the bloodstream through the digestive system, and 10 per cent of it remains unchanged. The alcohol blood solution passes through the alveoli in the lungs, and some alcohol from the lungs is exhaled into the air. Ten per cent of consumed alcohol leaves the body through the breath, perspiration and urine. The remainder is broken down through metabolism at the same rate in everyone regardless of height, weight, sex, race or other such characteristics.

Ratio of Alcohol Content

The amount of alcohol expelled from the lungs is proportional to the amount of alcohol in the blood. The ratio of alcohol exhaled to alcohol in the blood is 2,100:1, or 2,100ml of alveolar air contains the same amount of alcohol as 1ml of blood.

Potassium Dichromate

Potassium dichromate is red-orange in solution in the breathalyzer. Potassium dichromate oxidises alcohol, reducing it to acetic acid, while the potassium dichromate becomes green-blue chromium sulphate. The amount of alcohol in the solution in the breathalyzer determines the strength of the chemical reaction within it. The potassium dichromate is converted to chromium sulphate from yellow to blue to green, depending on the amount alcohol in the blood, breath or urine.

Dissipaton of Alcohol Concentration

Alcohol is metabolised at the rate of .015 (1.5 per cent) of blood alcohol concentration each hour. Thus, even an extremely high blood alcohol concentration will leave no measurable alcohol in the bloodstream after 10 hours.

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