Written by attorney David Nelson Jolly

The DUI Guide: DUI Evidentiary Breath Test Devices (Intoximeter)

Published with permission from the book, DUI/DWI: The History of Driving Under the Influence, David N. Jolly. Outskirts Press (2009)

The DUI Guide: DUI Evidentiary Breath Test Devices

Intoximeter In 1941 Professor Glen Forester from St. Louis, Missouri, developed the "Intoximeter." The Intoximeter's roots are that of a field testing device. This original machine consisted of a mouthpiece, a check valve, a balloon, a tube with permaganate-sulphuric acid, a tube with magnesium perchlorate and an ascarite tube. Since its inception there have been upgrades and several models known as the Intoximeter sold and utilized in the United States.

The original "field testing" Intoximeter used magnesium perchlorate to absorb carbon dioxide from the subject's breath sample. From there the alcohol was distilled from the perchlorate solution, and the amount of alcohol was determined by the colorimetric procedures. Once the sample was received it was analyzed in a the laboratory where the increase in weight of the ascarite tube was determined and thereafter the volume of the breath sample was calculated based upon an assumption that deep lung, or alveolar air of each person tested contained 5.5% carbon dioxide by volume.

This type of technology for breath test purposes died in the late 1960s when the National Safety Council recommended discontinuance of the use of any instrument which based alcohol analysis upon the carbon dioxide content of the breath sample. The retirement of this technology was due to the discovery that the carbon dioxide content of expired deep lung air among subjects was too variable to allow carbon dioxide to be used as a calculation for the volume of the breath sample. National Safety Council Committee on Alcohol and Drugs, A Model Program for the Control of Alcohol for Traffic Safety (1967); National Safety Council, Committee on Alcohol and Drugs, Recommendations of the Ad Hoc Committee on Testing and Training (1968)

The photoelectric Intoximeter replaced the original Intoximeter and is similar to the Breathalyzer in that they both utilize a photometer. This new unit measured alcohol in a specified amount of breath using the wet chemical oxidation reaction. This newer machine collected two breath samples, using two cylinders and in the first cylinder, the breath passed into the ampoule where the chemical reaction takes place. In the second cylinder, the breath is trapped by magnesium perchlorate and then stored for future analysis.

Not surprisingly the photoelectric Intoximeter had similar problems as did the Breathalyzer. However, surprisingly the photoelectric Intoximeter is still in use in some states.

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