Intoxilyzer 8000 and Problems with Slope Detection
One of the biggest problems with the Intoxilyzer 8000 involves the slowness of the IR system combined with relative insensitivity of the pyro electric detector. Basically, the Intoxilyzer 8000 only takes two pulses. Because the system is slow slow, it is nearly impossible for the instrument to obtain a proper slope detection. A study done by Al Staubus indicates that the Intoxilyzer 8000 may miss 40% or more of the obvious mouth alcohol indications.
These problems with the slowness of the system are compounded by the lack of precision in the optical filter bandwidth. In order to compensate, the Intoxilyzer 8000 must average the readings. Many of the continuing events in the analysis are never integrated into the final readings of the instrument. The manufacturer was able to save money when it built the machines, but these cost-saving measures sacrificed accuracy and reliability.
The pulsed source, because of its’ relatively slow operation results in a weaker and slower signal level from the detector. The pulsed source of the Intoxilyzer 8000 is 2 Hz at 6 to 10 mv. Other systems operate much faster. For instance, the Intoxilyzer 5000 operated at 120 Hz at 30 mv. The DataMaster operates at 500 Hz at 40 mv. The Intoxilyzer 8000 partially compensates for the slowness of the pulsed source by opening up the bandwidth of the optical filters to allow more energy to get to the detector.
Assumptions and Calculations Made by the Intoxilyzer 8000
The Intoxilyzer 8000 attempts to overcome these characteristics by taking an average the pulses over time. However, these averages then make it difficult to get a “real time” analysis since the computer generated reading always lags behind the events in the sample chamber. Consider these systemic problems that are unique to the Intoxilyzer 8000 which are covered up by certain known and unknown assumptions contained in the software:
- The Intoxilyzer 8000 has a lack of precision at lower levels cause by the weak signal level (6 to 10 Mv) at the detector. In fact, in the Intoxilyzer 8000 the software blanks everything below a .006.
- Often the slope detection is so ineffective that many breath samples containing known mouth alcohol conditions are missed by the slowness of the system which operates at 2 Hz per second. This fact is clearly in the Staubus Report.
- Lack of consistent agreement between first and second samples which is demonstrated by the two test routine used in Florida. The Staubus Report shows the lack of .02 agreeement on multiple tests that can result in a charge of refusal as the officers often interpret this as a sign of a non cooperative subject.
- A poor performance in detecting hydro carbons other than ethanol when present in the ethanol sample. Staubus did some work several years ago that compared the 8000 to other instruments. That work showed that the Intoxilyzer 8000 was inferior in its’ ability to detect many interferents that can be present during a breath test. In chemistry, the term interferent is defined as any substances that interferes with the analytical procedure and generates incorrect results.
- The pressure transducer that is used in the 8000 has some serious issues in precision and accuracy that can result in an inaccurate calculation of the volume of air being blown into the instrument. This can affect sample acceptance minimums and result in a charge of refusal as the officers often interpret this as a sign of a non cooperative subject. This problem is also demonstrated in the Staubus Report.
Infrared Absorption in the Intoxilyzer 8000
The most common technology used for the evidential testing of human breath for ethanol concentration involves infrared absorption. The instrument selected for use in Florida in 2002, the Intoxilyzer 8000, uses infrared absorption technology. A number of different compounds, specifically hydrocarbons, absorb infrared energy at known wavelengths. Each of the compounds will produce a unique pattern sometimes referred to as a “fingerprint”.
For alcohol breath testing, the wavelengths used for this analysis are between 3 and 10 microns. The most important part of the analysis involves determining with certainty that ethanol and not some other compound such as acetone is causing the absorption. Determining this specificity is done in several ways. In the Intoxilyzer 8000, credible defenses can be raised to challenge the ability of the machine to determine whether the reading produced resulted from the presence of ethanol as opposed to certain other compounds often called intererents.
Components of Infrared Absorption
The Intoxilyzer 8000 uses four critical components for infrared absorption:
- the device often called a “lamp” that actually produces the infrared energy;
- the “optical filters: which prevent the passage of any frequencies of infrared energy except for those which are designated;
- the “detector” which responds in proportion to the amount of infrared energy that is present; and
- the sample chamber.
The Infrared Source Lamp Used in the Intoxilyzer 8000
The infrared source lamp emits infrared energy within the frequency range that the filters and detector need to operate. The infrared source lamp also emits infrared energy at a level that is sufficient to cause a response from the detector. The Intoxilyzer 5000 uses high intensity photo projector lamps. These lamps less desirable because they are not particularly stable or efficient.
The output from these high intensity photo projector lamps is continuous. Because it is continuous, it needs to be chopped (or modulated) to function. The term “chopping” or “modulation” refers to the process of passing a physical element between the source and the detector so that the energy striking the detector is broken up into regularly alternating periods of light and dark producing a corresponding pattern of an alternating current output signal from the detector.
Problems with the Pulsed Source on the Intoxilyzer 8000
The Intoxilyzer 8000 uses a “pulsed source.” The pulsed source is composed of a material that can be heated but will also cool very quickly. This process of rapid heating and subsequent cooling produces a modulated stream of energy at the detector at a frequency of usually 2 to 4 times per second. One undesirable characteristic inherent in this “pulsed source” system is a profound limit of the operating speed of such a device. The main reason a breath test manufacturer would use such a system seems to center on the fact that such as system is much less expensive than other alternatives. For the Intoxilyzer 8000, the chopping is done by pulsing the power to the lamp rather than by physically blocking the energy.
The most expensive alternative is called the ”grey body” sources. “Grey body” sources are highly stabilized and produce a continuous stream of steady infrared energy. This technology uses a coiled tungsten metal operating on very low regulated voltages which is focused into the sample chamber for greater efficiency. These “gray body” sources operate continuously at close to 1000 degrees C on as little as 2 or 3 volts DC. Although the “grey body” lamp are much more expensive, they usually last for the life of the breath test machine. The “grey body” lamp also require far less chopping and operated at much greater speed thereby producing a more accurate breath test reading.
The complexity of these issues and the fact that the manufacturer of the Intoxilyzer 8000 keeps this information out of the reach of criminal defense attorneys explains why the courts throughout the State of Florida have failed to adequately address these issues. Viewing the remaining portions of the Intoxilyzer 8000 source code (those preserved in CMI’s “remaining documents”) are critical in understanding how these problems impact a particular breath test reading.
Leslie Sammis is a criminal defense and DUI attorney in Tampa, FL. Visit her main website to find out more about fighting drunk driving cases involving a high blow on the Intoxilyzer 8000 in Tampa, Hillsborough County, FL.
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