The Intoxilyzer 5000 uses, what is known as, infrared spectroscopy to determine how much ethanol is present in the breath sample of DUI arrestees. These machines essentially emit a beam of infrared light through a given air sample. Certain molecules absorb infrared light at certain wavelengths. After a breath sample is given, the machine takes note of the infrared light that does NOT make it through the sample. Then, using what’s known as the Lambert-Beer Law, the machine calculates the number of absorbing molecules in the air sample relative to the volume of the sample. This is how law enforcement establishes an arrestee’s blood alcohol level without actually taking blood.
Several problems exist with this method. First other naturally occurring molecules absorb infrared energy at the same or very similar wavelengths. The Intoxilyzer 5000 can mistake those molecules for ethanol. In fact, a high enough volume of acetone in the breath will result in an aborted test. Under these circumstances, law enforcement has been instructed, by the manufacturer, NOT to retest the subject using the Intoxilyzer 5000.
The Intoxilyzer uses multiple wavelengths of infrared energy to look for ethanol. Acetone, methane and unsaturated hydrocarbon isoprene are all “volatile organic chemicals” (VOCs) found on the breath of healthy human beings. Some of these VOCs are found in far greater quantities on the breath of people with diabetes and people engaging in voluntary fasting or those engaging in certain popular diets. These VOCs absorb infrared energy at the same, or similar, wavelengths to that of ethanol alcohol and can result in the machine registering a higher blood alcohol level than what a person actually has. As I mentioned previously, the manufacturer of the Intoxilyzer 5000 has a built-in way of detecting acetone, and aborting the test if quantities of acetone are too high. Fair enough. But what if the acetone is present, but not high enough to abort the test. What if other VOCs are present and absorbing the infrared energy?
Unfortunately, the vast majority of tests on these subjects are government-funded. Meaning, the people paying for the test have a vested interest in the studies’ outcome concluding that the Intoxilyzer 5000 is valid and reliable. One of the most noteworthy tests (from Sweden in the 1990s) only bothered to actually draw blood on those subjects whose Intoxilyzer tests aborted due to a high concentration of acetone. No effort has been made to analyze the impact of acetone levels in lower concentrations and no blood tests were done on any of the subjects whose tests were not aborted due to a high concentration of acetone.
Furthermore, with regard to methane the test stated “Methane should perhaps be considered as a potential interfering substance in connection with forensic breath alcohol analysis, but more research is necessary on this subject.” To my knowledge, no additional research has been done despite the fact that the testers also stated that, “It seems that some individuals are more prone than others to generate methane in the large intestine, and the concentration of this hydrocarbon expelled in breath under different conditions requires more documentation.”
You can read the full study here: http://jat.oxfordjournals.org/content/20/7/522.full.pdf
Considering the amazing source of power and revenue generated by DUI law, arrests and convictions, I seriously doubt the State will be funding research which may cast doubt on, what is currently, a sacred-cow of law enforcement. . . the Intoxilyzer 5000.
If you, or someone you know, have been arrested for DUI you should consult with an experienced and knowledgeable attorney. Please visit my website www.carnellfirm.com or call me at 770-729-4809.
- Jason Carnell