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Breath Analysis

Breath Test History

In 1937, Rolla Harger invented the "Drunkometer" for breath testing in DUI cases. This machine gave birth to a new industry in determining alcohol levels in an individual based on one's breath. The Breathalyzer was eventually invented in 1954 to collect evidence of intoxication by measuring BAC through breath analysis. Since that time, others have entered the breath-analyzer market and the science behind the machine has evolved.

In fact, the word "breathalyzer" is now widely used to refer to these apparatus regardless of manufacturer. Other terms used to refer to these devices include evidential breath tester (EBT), breath analyzer, breath-analysis product, breath-alcohol analyzer and breath-testing device or machine. In addition to Breathalyzer, common brands include Intoxilyzer and Intoximeter.

In very basic terms, the breath-test machine is designed to measure the amount of alcohol in a deep-lung breath sample and to use that amount to determine BAC. The four main scientific methods used in the various machines are chemical analysis, infrared spectrophotometry, gas chromatography and fuel-cell detection.

CHEMICAL ANAYLSYS: The last part of a breath, the alveolar air, is saved stored in an ampule, then heated to about 50 degrees Celsius. It is then mixed with a color reagent(potassium dichromate and sulfuric acid with a small amount of silver nitrate, which served as a catalyst for oxidation reaction) and the absorbency by the machine is then measured to provide the alcohol analysis.

INFRARED SPECTROPHOTOMETRY: This machine generally consists of a computer, a printer, a panel screen, an LED read-out, an infrared energy source, and sample chamber where the subject's breath and room air are alternatively analyzed. With this machine, an infrared beam of radiation is passed through the captured breath in the sample chamber to detect the alcohol level as a function of the wavelength of the beam, which produces an absorbency spectrum. The characteristic bond of alcohols in infrared is the O-H bond, which gives a strong absorbency at a short wavelength. The more light is absorbed by compounds containing the alcohol group, the less reaches the detector on the other side and the higher the reading.

GAS CHROMATOGRAPHY: This technique works by separating gases and liquids into their elemental components. The process is relatively quick, but in the case of BAC measurement, is still a tedious and routine job. Once the sample breath is obtained, it is injected into a heated reaction chamber where it will vaporize (if it is not already a gas). Then the sample is moved by an inert carrier gas through the stationary phase column that is a long tube made of either stainless steel or glass that has been tightly wound into a coil. This column may be up to six meters (19.7ft) long and only 3mm (0.12 in) in diameter! As you can imagine, this machine would be very difficult for a patrol officer to use in his vehicle and is seldom used anymore.

FUEL CELL DETECTION: The technology in the typical roadside PAS test is called "fuel cell" technology. This technology works by burning up the alcohol, which generates an electrical current that is measured and quantified with a numeric result. The technology in these roadside PAS tests is dubious at best. These devices do not have "slope" detectors, which are designed to guard against mouth alcohol causing an artificially high reading by detecting a negative slope (or sharp drop-off) in the alcohol level; they are not specific for alcohol, and are subject to error due to certain types of chemical buildup.

Breath-Test Vulnerabilities

As with any product and person using the product, there is a margin of error in both the product and user. A drunk-driving defendant, with the help of a scientific expert and experienced attorney such as one at Doan Law Firm, may be able to successfully challenge the breath-test results in his or her case. Several different factors may call into question the reliability of the results. A successful challenge would then make the BAC reading inadmissible in court or, if the BAC is still admissible, could cast serious doubt on whether the reading is reliable.

Arguments attorneys at Doan Law Firm make to undermine the breath-test results:

  • The breath tests' assumption of a 2100-to-1 blood-to-breath ratio is not scientifically reliable.
  • The police officer was not properly trained or qualified to administer the test.
  • The police officer administered the test incorrectly by not warming up the machine to the correct operating temperature or ensure an adequately deep lung sample.
  • The result was affected by other individual aspects of the driver, such as age, dental issues, fever or harelip, shock or trauma, lung function, overall strength and size, a disease or condition such as asthma, diabetes, eardrum rupture, ketosis, emphysema, bronchitis, certain types of special diets, or hiccupping, burping, vomiting or hyperventilating. Believe it or not, even severe heartburn will make the breath results unreliable.
  • The equipment was not maintained properly, calibrated correctly, or cleaned adequately.
  • The test administrator failed to take into account the fact that the driver placed mouthwash, adhesive, or lip ointment in or near his mouth prior to the test.
  • Police radio operation generated electromagnetic waves, causing radio frequency interference (RFI) with the testing equipment.
  • The driver was exposed to a gas or vapor before the test that made it unreliable, such as during painting, floor sanding, varnishing or other activity with chemical exposure. Similarly, an outside environmental cause in the surrounding air could have caused a high breath test result.

The forgoing only scratches the surface of some of the issues that the attorneys at Doan Law Firm look for in any breathalyzer test.


If you or a loved one experienced a breath test which provided a BAC analysis, it is critical to obtain a competent and experienced attorney who is thoroughly familiar with proper testing procedures and the science behind the tests. Just because the machine provides evidence that the BAC level was beyond the legal limit, the case is still not lost! But do not delay. Time is of the essence and so are an individual's civil liberties!

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