California DUI

Alcohol Breathalyzer Tests

DUI Los Angeles

There are many faults with the way a breath testing machine analyses the air that is introduced to it. These tests can be very unreliable and susceptible to attack by a California DUI defense lawyer who understands the weakness of a "Breathalyzer".

One of the major defects in many methods of blood-alcohol analysis is the failure to identify ethanol (also referred to as ethyl alcohol) to the exclusion of all other chemical compounds. To use the terminology of scientists, such methods are not specific for ethanol: They will detect other compounds as well, identifying any of them as "ethanol." Thus a client with other compounds in his blood or breath may have a high "blood-alcohol" reading with little or no ethanol in his body.

This problem of non-specificity is most noticeable in the use of infrared breath analyzing instruments (the most popular type of breath testing machines used today). Yet they are particularly susceptible to giving false readings due to non-specificity. The technical reason for this lack of specificity is that most breath machines are not designed to detect the molecule of ethyl alcohol (ethanol), but rather only a part of that molecule — the methyl group. In other words, it is the methyl group in the ethyl alcohol compound that is absorbing the infrared light, resulting in the eventual blood-alcohol reading. Thus the machine will "detect" any chemical compound and identify it as ethyl alcohol if it contains a methyl group compound within its molecular structure. The "Breathalyzer" assumes that the methyl group is a part of an ethyl alcohol compound.

The simple fact is that there are numerous compounds that contain the methyl group.

  • Isopropyl Alcohol
  • Propane
  • Butane
  • Propylene
  • Methane
  • Ethane
  • Ethyl chloride
  • Acetic Acid
  • Butadiene
  • Dimethylether
  • Dimethylamine
  • Dimethylhydrazine

Acetone and acetaldehyde, interestingly, can be found on the human breath. In fact, recent studies have found that over one hundred chemical compounds can be found on the breath at any given moment in time. More important, approximately 70 to 80 percent of these compounds contain methyl groups. And the infrared breath machine will detect each of these as "ethyl alcohol".

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California DUI