The State of Alabama adopts new breath test instrument – Intoximeters, Inc. DMT ‘Dual Sensor.’
Alabama’s first state approved breath test instrument was the 'Photo-Electric Intoximeter' [PEI] manufactured by Intoximeters, Inc. St. Louis, Mo. In 1971, with the legislature’s enactment of the ‘Chemical Test for Intoxication Act’ [now codified at Code of Alabama, 1975, section 32-5A-194], the state of Alabama decided to use the PEI as the sole evidentiary instrument for breath testing. The PEI was a wet chemical type breath test device that relied on the oxidation of potassium dichromate in a solution of sulfuric acid. When ethanol (alcohol) was introduced into the solution, the solution would change colors from deep or dark yellow to a much lighter pale yellow. The amount of color change as measured by a light meter was indicative of the amount of ethanol in the breath. This method was commonly referred as a ‘colorimetric testing’ and was very similar in operational theory to the well-known ‘Breathalyzer’ instrument first developed in 1954.
The PEI was replaced by the CMI’s Intoxilyzer 5000 in 1984. The Intoxilyzer operated on a completely different scientific principle of infrared light absorption. Ethanol, like other chemical substances, can absorb specific wavelengths of infrared light based on its unique chemical structure. The basic analytical components, or “optical bench,” of an Intoxilyzer 5000 are the quartz iodide infrared light source, chamber lenses, sample chamber, rotating chopper/filter wheel (3 filters), and detector. The light generated by the infrared light source is passed through the sample chamber. The wavelengths chosen for analysis by the Intoxilyzer 5000 are a 3.80 micron baseline reference, a 3.48 micron, and a 3.39 micron. The instrument’s microprocessor utilizes a ratio comparison of the signals produced at these wavelengths to establish specificity to ethanol.
The Intoxilyzer 5000 was replaced in 1999/2000 by the then state of the art Draeger 7110. The Draeger 7110 served the state of Alabama for over 15 years as the sole evidential breath test instrument. Noteworthy about the Draeger was the dual analytical capability – the ability to examine each breath sample by use of infrared (IR) and electro-chemical (EC). However, after over 15 years of continuous service, the Draeger instruments are at the end of their service life and are no longer economically repairable. In November 2015, after a one-year test and evaluation, the Intoximeters, Inc. DataMaster DMT "dual analytical" instrument was selected as Alabama’s newest and state of the art breath test instrument and is now replacing the Draeger 7110 as the sole breath test instrument for the state of Alabama. [See photo.]
Like the current Draeger, the Intoximeter DMT “dual analytical” instrument will utilize two detectors for ethanol – both infrared and fuel cell. The Intoximeter DMT will make an administrative correction to 100% of all breath test samples to account for variations in breath temperature and measurement uncertainty. In addition, each instrument will be connected via the internet to the DFS server which will allow for real time monitoring of the program. The Intoximeter DMT employs the well-established principles of infrared spectroscopy for the purpose of measuring the level of ethanol in breath samples for forensic purposes. Infrared (IR) energy is part of the electromagnetic spectrum and measured in wavelength expressed as micrometers (μm). When a molecule is exposed to IR energy the bonds of the molecule will absorb the energy at a specific wavelength. The wavelengths used in the Intoximeter DMT are 3.37 μm, 3.44 μm, and 3.50 μm. An Intoximeter designed and manufactured fuel cell is added to the DMT (thus, giving the designation “DMT dual analytical” capability) to allow duplicative testing by two scientifically accepted test methods of a single breath sample.
Other features of the Alabama Intoximeter DMT program include:
- The current test protocol of two admissible tests, taken at least two minutes but not greater than fifteen minutes apart, will be retained.
- The current test parameters of each test sample requiring 1.3 liters of air/2 atmospheres of pressure/4 seconds of exhalation will be retained.
- The current dry gas calibration check of .02% and .08% for each test cycle will be retained, but a third dry gas calibration check of .15% will be added when the subject’s test result is .15% or greater.
The Intoximeter DMT Optical Bench