600 Forest St. #101
Georgetown, Texas 78626

DWI Case Intoxilyzer 9000

What is the Intoxilyzer 9000?

This machine is used to determine a driver’s blood alcohol content after being arrested for DWI or the other variations of operating such as DUI, DWI, BWI etc. The Intoxilyzer 9000 is the alcohol breath test machine that Texas and many other states use. Texas has used it since 2015 replacing the Intoxilyzer 5000.

The Intoxilyzer 9000 measures a breath test by giving grams of alcohol per 210 liters of breath. When testing a driver’s breath the machine operator will have the driver blow into the machine twice within 3 minutes. The two readings my not be farther apart than 0.02 g/210 L.

Lambert-Beer Law

The Intoxilyzer 9000 uses the Lambert-Beer Law which states that the amount of energy absorbed by a particular substance is proportional to the number of absorbing molecules in the sample. The amount of infrared energy absorbed in a breath sample is proportional to the amount of ethanol present in a breath sample blown into the sample chamber.

Infrared Spectrometry Breath Test

The Intoxilyzer 9000 uses infrared spectrometry (IR) to measure alcohol in breath. IR analysis is the absorption of infrared energy by alcohol molecules in breath. It measures the absorption of radiant energy by a substance.

IR is a lower frequency wavelength than the visible light that we see. The amount of IR energy absorbed by the breath sample is proportional to the amount of ethanol (alcohol). This is again measured as grams of alcohol per 210 liters of breath. The machine uses multiple wavelengths of IR energy to detect substances in the breath. The machine is supposed to be able to differentiate between different substances in the breath such as alcohol and acetone.

Diabetic Ketoacidosis

Diabetic ketoacidosis is a condition with diabetics where their breath smells like acetone. This is due to a high number of ketones in their blood. When the body breaks down fatty acids for energy the liver releases ketones. When there is too much glucose in the blood and not in the cells the ketones can rise too high.

Intoxilyzer Calibration

The machine like other machines requires maintenance. Part get worn and break. The 9000 needs to be calibrated or it is not accurate. It only measures as well as it is calibrated. There is a simulator solution that delivers a known measurement of alcohol to the machine to test and calibrate the instrument. This is a calibration verification.

Known solutions are created by technical supervisors and are called reference sample solutions. If the reference sample solution is miscalculated or wrong the machine’s test reading will be inaccurate as well. Two calibration verifications are conducted for each test done. The acceptable range for the calibration verification is 0.070 to 0.090 g/210 L. Any results outside this range will stop the test.

The solution must be between 33.80 to 34.20 degrees celsius. The instrument is supposed to stop the test if outside this range.

15 Minute Observation

For the breath test results to be valid the breath test operator must be in the presence of the test subject AT LEAST 15 minutes immediately before the test. This is to ensure that the subject has not placed any substance in their mouth. The 15 minute observation needs to be repeated if anything is put into the subjects mouth. This is to make sure there is no mouth alcohol present. Only certified breath test operators may conduct a 15 minute observation.

If the two tests differ by more than 0.02 g/210 L it would likely indicate residual or mouth alcohol and the breath test is invalid. This can happen if a person burps. That would be an inaccurate breath test because stomach gas would spike the alcohol IR reading.

The 9000 requires the operator to check the blue button by tapping it and typing yes that the 15 minute observation was conducted. The operator must sign in the box on the touchscreen.

Starting the Intoxilyzer 9000

After signing the box for the observation period the machine begins a testing sequence by checking itself. Any errors that the machine has are supposed to show. How do we know the self testing is not flawed? The machine conducts air blanks during the process and purges the sample chamber with room air. This result tested must be 0.00 or the 9000 is supposed to stop.

Once the machine is started the operator asks the subject to blow steadily into the machine twice. All evidential tests are stored in the Intoxilyzer 9000 in PDF documents. The report can be printed out at any time.

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