An Independent Review of the Intoxilyzer 9000
Part 2 - Specificity towards ethanol detection
From - Counterpoint Volume 2; Issue 2 - Article 4 (August 2017)
Jan Semenoff, BA, EMA
Forensic Criminalist
The opportunity to conduct an independent analysis and performance review of a new breath alcohol testing device is rare, particularly the higher-end, evidentiary-level units. Access to these technologies is stringently controlled by both their manufacturers and the police and government agencies that control them. Additionally, state agencies are often reluctant to publish the results of their official assessments and analysis of the devices.
When given the opportunity to perform such a review on a new Intoxilyzer 9000, I designed a series of experiments to quickly analyze the overall performance of the device. I attended the device’s location with colleague Tom Workman (1948-2019) to determine its suitability and reliability in a number of key areas, including:
The opportunity to conduct an independent analysis and performance review of a new breath alcohol testing device is rare, particularly the higher-end, evidentiary-level units. Access to these technologies is stringently controlled by both their manufacturers and the police and government agencies that control them. Additionally, state agencies are often reluctant to publish the results of their official assessments and analysis of the devices.
When given the opportunity to perform such a review on a new Intoxilyzer 9000, I designed a series of experiments to quickly analyze the overall performance of the device. I attended the device’s location with colleague Tom Workman (1948-2019) to determine its suitability and reliability in a number of key areas, including:
- Overall design and ease of use
- Accuracy in determining in vitro BrAC levels using a simulator
- The ability of the device to determine the presence of Fresh Mouth Alcohol using a Residual Alcohol Detection System (RADS) or the so-called “slope detector”
- Reliability in reporting BrAC [1] readings that are highly specific to ethanol
- The effect of Radio Frequency Interference on the device [2]
This article will examine the unit’s specificity towards ethanol detection, and its ability to identify the presence of an interferent chemical. Part one provided a general overview of the performance characteristics of the Intoxilyzer 9000, looked at the apparent accuracy of the device using simulator readings, and examined the ability of the device to “flag” false-positive readings caused by fresh mouth alcohol contamination. Part three will examine the capacity of the device to detect Radio Frequency Interference.
An important caveat:
This assessment on an individual Intoxilyzer 9000 was done in circumstances of complete access to the device, but under limited time constraints. Simply put, we did not have the time necessary to run exhaustive testing on the 9000 to generate the raw data necessary to ensure a proper statistical analysis. Over a ten-hour period, we were able to run about 60 individual tests on the 9000, and inspect its interior and component parts. We need further access to these devices to draw meaningful conclusions.
As an editorial position, Counterpoint, calls on the manufacturers of ALL breath test instruments, and all government agencies that operate and control them, to make these devices, used in criminal proceedings as evidentiary collection devices, available for independent review and analysis. Transparency regarding both the physical and software design, their manufacture, and the maintenance and operation of the devices is critical in maintaining a degree of openness and trust towards the numerical BrAC results generated.
This assessment on an individual Intoxilyzer 9000 was done in circumstances of complete access to the device, but under limited time constraints. Simply put, we did not have the time necessary to run exhaustive testing on the 9000 to generate the raw data necessary to ensure a proper statistical analysis. Over a ten-hour period, we were able to run about 60 individual tests on the 9000, and inspect its interior and component parts. We need further access to these devices to draw meaningful conclusions.
As an editorial position, Counterpoint, calls on the manufacturers of ALL breath test instruments, and all government agencies that operate and control them, to make these devices, used in criminal proceedings as evidentiary collection devices, available for independent review and analysis. Transparency regarding both the physical and software design, their manufacture, and the maintenance and operation of the devices is critical in maintaining a degree of openness and trust towards the numerical BrAC results generated.
The Intoxilyzer 9000
Specificity towards ethanol detection
We have examined the Intoxilyzer 9000 in three prior Counterpoint articles:
Article: Reference:
The New Intoxilyzer 9000 Archived
The Intoxilyzer 9000 & the Unknown Archived
The Intoxilyzer and Residual Mouth Alcohol Detection Volume 2, Issue 2, Article 3
Article: Reference:
The New Intoxilyzer 9000 Archived
The Intoxilyzer 9000 & the Unknown Archived
The Intoxilyzer and Residual Mouth Alcohol Detection Volume 2, Issue 2, Article 3
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First, we should agree on the definition of some terms:
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Figure 1 - The Intoxilyzer Model 9000
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Creating a Breath Alcohol Concentration (BrAC) reading
The breath sampling system
The breath sampling system consists of a series of tubes, both external and internal, that draw in room air, breath samples, and calibration solution vapors or dry gas into the optical chamber (or optical bench). Additionally, this sub-assembly requires opening and closing of valves in sequence, and a means to measure the flow rate of the exhaled test subject’s breath sample.
The Intoxilyzer 9000 has specific requirements in determining the suitability of a breath sample. First, it requires a minimum flow rate of 0.15 litres per second, with a minimum breath time of five seconds. The sample provided must be a minimum of 1.1 litres in volume.
In most breath alcohol testing devices, the volume determination is usually a calculated value (as opposed to a measured value). The volume reading is created by multiplying the flow rate, in litres per second, by the number of seconds the flow meets the minimum criteria to determine the calculated volume of exhaled breath:
FLOW RATE (litres/sec) x SECONDS OF EXHALATION = CALCULATED BREATH SAMPLE VOLUME (litres)
I have no information on how the Intoxilyzer 9000 creates this reported volume value.
The Intoxilyzer 9000 has specific requirements in determining the suitability of a breath sample. First, it requires a minimum flow rate of 0.15 litres per second, with a minimum breath time of five seconds. The sample provided must be a minimum of 1.1 litres in volume.
In most breath alcohol testing devices, the volume determination is usually a calculated value (as opposed to a measured value). The volume reading is created by multiplying the flow rate, in litres per second, by the number of seconds the flow meets the minimum criteria to determine the calculated volume of exhaled breath:
FLOW RATE (litres/sec) x SECONDS OF EXHALATION = CALCULATED BREATH SAMPLE VOLUME (litres)
I have no information on how the Intoxilyzer 9000 creates this reported volume value.
The optical chamber (also called: the sample chamber, or the optical bench)
The optical chamber, often referred to an as optical bench or simply “sample chamber”, consists of a chamber, tube or pathway in which both the room air, wet-bath solution vapor or dry-gas calibration standard, or exhaled breath sample are analyzed. Light or heat energy will also pass through the air, gas, or breath sample to determine the presence and concentration of ethanol in the sample.
Figure 2 - Schematic diagram of the sample chamber (optical bench) of the intoxilyzer 9000
We do not know the internal volume of the actual sample chamber in the 9000. Externally, it measures about 10” x 2” x ¾”. This internal volume is critical, in that larger optical chambers require a larger exhalation volume. A larger sample is also thought to deliver a more analytically precise measurement. Folded-path chambers are often utilized to deliver a more precise measurement as well. We know the 9000 does not utilize a folded pathway.
Although we don’t know its precise internal volume, or physical specifications, the external dimensions give rise to an internal volume around 15 cubic inches, or about 240 mL. This is perhaps an over-estimate of its internal volume, given that the Intoxilyzer Model 5000 had a sample chamber of around 80 mL, and the Model 8000 a volume of only about 29 mL. Older units employed aluminum chambers that were sensitive to pitting and corrosion, or that promoted the growth of mold over time. Some devices use polished stainless-steel chambers that minimize this contamination or corruption. What are the 9000’s characteristics in this regard?
Although we don’t know its precise internal volume, or physical specifications, the external dimensions give rise to an internal volume around 15 cubic inches, or about 240 mL. This is perhaps an over-estimate of its internal volume, given that the Intoxilyzer Model 5000 had a sample chamber of around 80 mL, and the Model 8000 a volume of only about 29 mL. Older units employed aluminum chambers that were sensitive to pitting and corrosion, or that promoted the growth of mold over time. Some devices use polished stainless-steel chambers that minimize this contamination or corruption. What are the 9000’s characteristics in this regard?
The sample chamber is also heated by an external warming blanket. We measured the temperature of the interior of the chamber at 47.0°C, within its stated value range.
The infrared source
Another component of the Optical Bench is its infrared source. The Intoxilyzer 5000 used a halogen light bulb as its infrared source. The 8000 used a pulsed infrared source, as apparently does the 9000, now incorporating pulsing LEDs (Light Emitting Diodes).
This is important in assessing the reliability of the interferent detection system. In the older 5000, the filter wheel component spun at around 1800 RPM. This meant that, for a ten second exhaled breath sample, about 300 readings were obtained from EACH filter. For the Model 5000EN, with five filters, this meant that 1500 discrete readings were obtained, analyzed and compared.
This is important in assessing the reliability of the interferent detection system. In the older 5000, the filter wheel component spun at around 1800 RPM. This meant that, for a ten second exhaled breath sample, about 300 readings were obtained from EACH filter. For the Model 5000EN, with five filters, this meant that 1500 discrete readings were obtained, analyzed and compared.
The Model 8000 moved from a Halogen light bulb and spinning filter wheel to a wire that was heated and cooled 2 times per second (4 Hz pulse). Only two filter points were utilized. That meant that in a ten-second exhaled breath sample, about 80 discrete readings were obtained, analyzed, and compared. As such, the so-called slope detector was less precise. Third-party testing indicated that the Residual Alcohol Detection System on the Model 8000 was less reliable than on the older 5000.
The IR source on the Intoxilyzer 9000 pulses at about 10 cycles per second (Hz). With four filters, a breath sample reading is obtained every 1/10 of a second (100 milliseconds) on each of the four-filtered points, for a total of 40 discrete pulses per second. As the pulses are analyzed, consecutive BrAC readings that do not differ by a predetermined margin will indicate a level slope. Once the four criteria (flow rate, time, volume and slope) are met, a ZERO appears in front of the preliminary breath test results, indicating the sample obtained is suitable for analysis.
The IR source on the Intoxilyzer 9000 pulses at about 10 cycles per second (Hz). With four filters, a breath sample reading is obtained every 1/10 of a second (100 milliseconds) on each of the four-filtered points, for a total of 40 discrete pulses per second. As the pulses are analyzed, consecutive BrAC readings that do not differ by a predetermined margin will indicate a level slope. Once the four criteria (flow rate, time, volume and slope) are met, a ZERO appears in front of the preliminary breath test results, indicating the sample obtained is suitable for analysis.
The infrared filters
In addition to the infrared source, the infrared filters provide a precise way to measure the ethanol concentration within the test chamber. The older Model 5000 had reported filter specification of 3.39µ (micron), 3.48µ, and 3.80µ, etc. The Model 8000 did not report the specific wavelengths used, but we came to know that they were at 3.4µ and 9.36µ.
The 9000 filters are apparently somewhere ≥8µ but, ≤9µ. Four discrete filters are used, with specific wavelengths and resolution (or tolerance) undisclosed
The 9000 filters are apparently somewhere ≥8µ but, ≤9µ. Four discrete filters are used, with specific wavelengths and resolution (or tolerance) undisclosed
Figure 3 - The infrared spectra of ethanol, showing the range of readings in earlier Intoxilyzer Model 5000s (Left: 3.3 - 3.8 micron) versus the newer Model 9000 (Right: 8-9 micron range).
The resolution of the filters is also important. IR filters are either narrow-bandwidth or wide-bandwidth. Think of this as narrow versus wide resolution. The wider a filter, the more IR light it absorbs. See the diagram on the left, below. The narrow a filter, the more specific and precise it is at absorbing an IR energy bandwidth. See the diagram on the right, below. This is important, as it speaks to the unit’s specificity towards ethanol. The Model 8000 apparently had a tolerance to the filter of +/- .5 micron from target. This is too large, implies inherent measurement uncertainty, and can lead to false-positive readings when interferent chemicals are present. How does the Intoxilyzer 9000 compare in this regard?
Figure 4 - The effect of wider bandwidth filters is to allow more false-positive readings, shown here in red. The bandwidth and programmed tolerance allow the red points to be misinterpreted as a correct "hit" against the blue target point.
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Figure 5 - By incorporating a narrower bandwidth filter, and tighter programmed instrument tolerances, the offending false-positive points, shown in red, are NOT interpreted as correct values versus the blue target point. This makes the device more highly specific to the target value desired.
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Measurement of interfering chemicals
Methodology and Findings
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Due to time constraints, we tested acetone and isopropanol is various small measures to simulate the effects of a diabetic test subject, or a person who was fasting, or on severe dietary restrictions. Methanol and d-limonene are well-established interfering substances used in occupational settings, so low levels of these chemicals were introduced as well. In order to assess the ability of the Intoxilyzer 9000 to determine the presence and concentration of ethanol, and its ability to identify and discern the presence of an interfering chemical, we used the following methodology:
A simulator, heated to 34.0°C, containing a 500-mL solution of ethanol in distilled water, had its vapor introduced into the Intoxilyzer 9000 through the external sample hose. The solution was allowed to come to equilibrium through agitation prior to being introduced. A baseline reading was obtained that indicated an equivalent BrAC reading in grams of ethanol per 100 mL of blood (210 L of breath) prior to the introduction of the potential interferent chemical to the ethanol solution.
To this known baseline solution, interfering chemicals were added in small aliquots[1], and also allowed to come to equilibrium through agitation. Laboratory-grade isopropanol, acetone, methanol and d-Limonene were utilized, in combination with one another and fresh ethanol mixtures. This compound solution of ethanol and the interfering chemicals had their vapor introduced into the Intoxilyzer 9000, again through the external sample hose. These are shown in the slideshow below, with ethanol shown in red. |
Figure 6 - A Guth Model 2100 simulator, used in these experiments for in vitro testing of potentially interfering chemicals.
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Figure 7 - A comparison of the infrared spectrographs of ethanol, shown in red, versus common interferent compounds (methanol, acetone, isopropanol and d-limonene).
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[1] An aliquot is a portion of a larger whole, especially a sample taken for chemical analysis or other treatment.
Figure 8 - The traditional "Ball & Stick" model showing the layout and number of molecules in the compound. Carbon atoms are shown in grey, hydrogen atoms in black, and oxygen atoms in light blue.
The reading produced by the combination of ethanol and interfering compound were compared to the true value of the baseline solution on the preliminary results displayed on the instrument. Additionally, the results of any error or status message were recorded, along with the final displayed apparent BrAC reading.
The reading produced by the combination of ethanol and interfering compound were compared to the true value of the baseline solution on the preliminary results displayed on the instrument. Additionally, the results of any error or status message were recorded, along with the final displayed apparent BrAC reading.
Data obtained:
The following table summarizes the data obtained:
Chart 1 - Response of the Intoxilyzer 9000 to various interferent chemicals.
Discussion:
Preliminary results indicate that the Intoxilyzer Model 9000 is capable of identifying the presence of even extremely small amounts of isopropanol, acetone (and various combinations of these two chemicals), methanol and d-limonene, all in the presence of ethanol at different concentrations.
Figure 9 - The "Ball & Stick" model of isopropanol (top) versus acetone (bottom).
I have performed similar testing on other instruments, including the Intoxilyzer 5000, 5000EN, 8000, and the DataMaster DMT. Only the DataMaster DMT has been equally successful in identifying interfering chemicals and aborting the BrAC testing process. The older Intoxilyzer 5000 and 5000EN often produced false-positive readings, as did earlier versions of the Intoxilyzer 8000. Later versions of the 8000 more correctly identified these specific interferent chemicals. In short, specificity of readings seems to be increasing in the Intoxilyzer line of evidentiary breath test products.
However, there are a wide variety of other chemicals (MEK, or methyl ethyl ketone; toluene; diethyl ether; dimethyl sulfone; xylene, etc.) that have been shown by various researchers to provide false-positive readings on different evidentiary breath test devices. Each of these, in combination with different ethanol readings, should also be tested to determine their response, if any, on the Intoxilyzer 9000.
The slideshow below shows ethanol in red, with other potential interferent chemicals.
The slideshow below shows ethanol in red, with other potential interferent chemicals.
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Figure 9 - The infrared spectrographs of ethanol (red) versus other potential interfering compounds. These additional compounds still need to be tested on the Intoxilyzer Model 9000.
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It has been long established among OSHA (Occupational Health & Safety) professionals that long-term, chronic exposure to various chemicals presents a health hazard. Simply put, a low-level of exposure to a specific substance can build up in the worker’s tissues over time, developing fairly high levels, often well beyond what a non-exposed person can develop. Simulating chronic exposure to chemicals in combination with ethanol becomes problematic, as it is often very difficult, or even impossible, to determine what the baseline interferent levels are present. The notion of plumbers with their heads under the sink cabinet gluing pipes with Methyl Ethyl Ketone (MEK) all day long, then stopping on the way home for a beer or two is not out of the realm of possibilities. Similarly, a hair stylist who works long hours dealing with straightening, coloring, bleaching chemicals, and hairspray[1] can develop significant chronic exposure levels to these inhaled chemicals. What effect these chemicals have, in concert with a low level of ethanol, needs to be examined in the Intoxilyzer 9000, and indeed, all other evidentiary infrared breath testing devices. |
Figure 10 - The hair dye and bleaching products used professionally in North Americas are banned in most parts of Europe and Australia, due to the constituent chemicals used in the products. What effect do these volatile organic compounds have, if any, on infrared breath alcohol testing devices?
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[1] Hair spray products are often a blend of industrial polymers to provide structural support for the hair. These frequently include chemicals used to achieve the desired physical properties (adhesive strength, foaming, etc.), often using plasticizers, surfactants, and other agents. These active ingredients make up only a small portion of a hairspray (aerosol can). The majority of a canister is filled with volatile solvents necessary to solubilize and aerosolize the copolymer mixture. These include simple alcohols like ethanol or tert-butanol to solubilize the active ingredients, and diethyl ether or mixed hydrocarbons as propellants.
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Practice Tip: Does your client have an occupation that exposes them to chemical compounds either in high concentrations (acute exposure) or constant low concentrations (chronic exposure) that could potentially affect their breath test results? Is this even possible? |
Conclusion
- In ALL instances, the Intoxilyzer 9000 correctly identified the presence of the interfering chemical and produced the error message “INTERFERENT DETECTED”.
- In no instance did the preliminary digital display indicate a BrAC reading beyond the true baseline value.
- Our testing indicated that the Intoxilyzer 9000 performed better than most other devices in this regard, identifying the presence of interferent chemicals on par with the DataMaster DMT. Later versions of the Intoxilyzer 8000 also correctly identified interferent chemicals the majority of times.
Send me your questions or comments:
Comments and questions will be posted here with their responses:
Comments and questions will be posted here with their responses:
For further study:
- Bailey, D, Detection of Isopropanol in Acetonemic Patients Not Exposed to Isopropanol, Clinical Toxicology, 28(4), 1990, Pages 459-466.
- Dubowski, K.M. Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects, 10 J. Stud. Alcohol Suppl. (1985).
- Dubowski, K.M., Stages of Acute Alcoholic Influence/Intoxication, Indiana University Center for Studies of Law in Action, The Borkenstein Course (course material), 2006.
- Dubowski, K.M., Alcohol Determination in the Clinical Laboratory, American Journal of Clinical Pathologists, Volume 74, No. 5, Pages 747-750, 1980.
- Jones, A.W., Andersson, L., Biotransformation of Acetone to Isopropanol Observed in a Motorist Involved in a Sobriety Check, Journal of Forensic Sciences, JFSVA, Vol. 40, No. 4 July 1995, Pages 686-687.
- Jones, A.W. & Summer, R., Detection of Isopropyl Alcohol in a Patient with Diabetic Ketoacidosis, The Journal of Emergency Medicine, Vol. 19, No. 2, 2000, Pages 165-168.
- Jones, A.W. & Rossner, S., False-Positive Breath Alcohol Test After a Ketogenic Diet, International Journal of Obesity, (2007) 31, Pages 559-561.
- Jones, A.W., Interfering Substances Identified in the Breath of Drinking Drivers with Intoxilyzer 5000S, Journal of Analytical Toxicology, Vol. 20, November/December 1996, Pages 523-527.
- Jones, A.W., Observation on the Specificity of Breath Alcohol Analyzers Used for Clinical and Medicolegal Purposes, Journal of Forensic Sciences, JFSCA, Vol. 34, No. 4, July 1989, Pages 842-847.
- Laasko, O., Pennanem, T., et al, Effect of Eight Solvents on Ethanol Analysis by Draeger 7110 Evidential Breath Analyzer, Journal of Forensic Science, Sept 2004, Vol 49, No. 5.
- Norfold, G. & Quartly, C., Volatile Substances and their Potential to Interfere with Breath Alcohol Reading Instruments, Journal of Clinical Forensic Medicine (1997) 4, Pages 21-23.
