The Intoxilyzer 5000
The Intoxilyzer 5000 is the breath testing machine which is used by law enforcement in Connecticut to test for the presence of alcohol when they have arrested a person for DUI. The company CMI in Kentucky manufactures the machine, which uses infrared spectroscopy to identify molecules based on the way they absorb infrared light.
All molecules are constantly vibrating, and these vibrations change when the molecules absorb infrared light. The changes in vibration include the bending and stretching of various bonds. Each type of bond within a molecule absorbs infrared light at different wavelengths, therefore in order to identify ethanol in a sample, one must look at the wavelengths of the bonds in ethanol (C-O, O-H, C-C) and measure the absorption of infrared light. The absorption wavelengths help to identify the substance as ethanol, and the amount of infrared absorption tells you how much ethanol is present.
The Intoxilyzer has a cell in which a person blows into the device. There is an inlet for the cell (2) and there’s an exhaust portion of the cell (3), and a sample chamber (4) that the breath travels through. (See Figure F) The light source is like a regular light bulb, producing energy. It is the same type of energy that an electric stove emits and that one can feel when the burner turns red.
The device has a wheel at the outlet of the chamber where the light goes through and there are five different filters (6). Those are like sunglasses. Each filter is different, and they filter out all unwanted light and only let small portions of light come through. As that wheel goes around you get small pulses of energy impacting the receptor as the filters break it up. The amount of heat that is sensed goes through what is called an “A to D” convert.
The computer system does not automatically recognize that type of signal. It has to be converted to a digital signal and then sent to the computer where it is then reduced to numerical values. That numerical value is shown on a small screen on the face of the device and it prints a readable report or readable result.
Henry’s Law
Breath testing is based on the principle known as Henry’s Law. This can be related to blood in a closed container that contains alcohol. The alcohol will evaporate until the concentration in the air above the liquid is equal to that in the liquid, also known as a fixed constant or Henry’s Constant. The ratio given to that of the blood in the human body to be used in accordance with Henry’s Law is 2100:1. This can be explained as “the concentration of alcohol in a normal person’s blood is said to be approximately 2100 times as great as the concentration in the air in equilibrium with it. This means that if the alcohol concentration found in blood that is in equilibrium with the alcohol in air, the alcohol concentration in the blood should be close to 2100 times greater.” Another problem exists by this normal ratio because not every person has the same body weight, frame and physical makeup, therefore there cannot be a norm for his or her blood/air equilibrium. The ratio would be much wider depending on the person being tested because the human body is not an ideal subject for a sealed container. Because of this problem with the normal ratio determined by forensic scientists, there can be up to a 0.03% error or more with a breath machine due to the normal ratio being used as a constant with the breath machine.
In addition to the issues of the ratio of the breath machine, the temperature of the individual supplying the sample can impact the reported results. Rarely does the defendant’s temperature get taken at the time the sample is given, but it could severely alter the results of the test! A temperature increase of only 2°F will cause approximately a 10% increase in BAC due to the volatility of alcohol. A drop in temperature can cause similar results. A heavy dose of aspirin can cause body temperature to be reduced and thus potentially alter results. There is a breath machine that corrects a test result based on temperature, however that machine is not used in Connecticut.
These two issues of breath can be used as a viable defense when being charged with a DUI. If you have taken any medication or have been sick, it is a good idea to tell the officer when they question you, or to tell your attorney afterwards. Also, if you have any medical conditions that could affect your normal blood ratio, you should let your attorney know so that he/she may obtain the correct medical documentation to support your claims. If you are a diabetic, the officer and your attorney should know because a diabetic can naturally produce ketones, which can skew the results of the breath test. A dedicated DUI attorney can review your medical history and investigate any possible medical defenses to the charges brought against you.
There are a few variations of breath machines, but many are outdated or not used in Connecticut. The Breathalyzer and hand held breath testing machines are no longer used and not valid, respectively. Currently the state is in the process of passing laws that put breath machines in a system within a person’s vehicle, known as the ignition-interlock program, part of Public Act 03-265.
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