The Effect of Volatile Substances on the Intoxilyzer 5000C Breathtesting Instrument

R.C.M.P. Forensic Laboratory, Alcohol Section, 15707 - 118 Avenue, Edmonton, Alberta, Canada

ABSTRACT

There are individuals who drink methanol and isopropanal for their intoxicating properties as well as their ease of attainment. This study looks at the ability of the Intoxilyzer 5000C to detect non-ethanolic substances in a breath sample.

The Intoxilyzer 5000C uses infrared technology to measure the amount of ethanol in a breath sample. It measure the absorbance of infrared light at three different wavelengths - 3.39, 3.48 and 3.80 microns. Vapours from simulator solutions containing methanol, isopropanol, ethanol and acetone, alone and in combination, at various concentrations, were tested to check the instrument for specificity.

When vapours from simulators containing high concentrations of methanol or isopropanol were introduced into the instrument, an "interferent" message was produced. Combinations of isopropanol/ethanol, acetone/ethanol and acetone/isopropanol usually produced an "interferent" message. The Intoxilyzer 5000C appeared to be less specific for methanol as combinations of methanol and ethanol gave additives results.

The Intoxilyzer 5000C is capable of detecting substances other than ethanol as an "interferent".

INTRODUCTION

The Intoxilyzer 5000C is a breathtesting instrument that utilizes infrared technology to measure the amount of ethanol in a breath sample. It measures the absorbance of infrared light at three wavelengths. The 3.39 micron wavelength is for the detection and quantitation of ethanol, the 3.48 micron wavelength is for the detection of interfering substances and the 3.80 micron wavelength is a reference point. The 3.80 micron wavelength was chosen as there is no reactivity to the ethanol molecule or any other substances that are found on the breath of normal individuals. In some groups of the population, methanol and isopropanol are consumed for their intoxicating properties as well as their ease of attainment. A significant concentration of acetone can be present in an individual due to the consumption of isopropanol or from ketoacidosis. All of these compounds will react under the conditions of the Intoxilyzer 5000C. However, if these substances are present in the body in high enough concentrations, the instrument will display an "INTERFERENT" message. The purpose of this paper was to determine how the Intoxilyzer 5000C responds to various concentrations and combinations of ethanol, isopropanol, methanol and acetone.

METHOD

Simulator solutions containing various concentrations of isopropanol, ethanol, methanol and acetone, alone and in combination, were tested using the Intoxilyzer 5000C. All of the solutions were prepared using newly opened bottles of chemicals having assays greater than 99.5%. The solution concentrations were verified by gas chromatography. All of the ethanol solutions, including the ones used for calibration, were apparent concentrations and the isopropanol, methanol and acetone solutions were actual concentrations.

The instrument was placed in the ABA mode (air blank/breath test/air blank) for all of the testing so all samples were introduced through the breath port. A series of fifteen tests was conducted on each solution.

The calibration of the instrument was checked before and after each series of tests. A simulator containing 100 mg% ethanol was attached to the side simulator vapor port and back exhaust port of the instrument. When the calibration check procedure is initiated, a pump within the instrument draws alcohol-laden air through the simulator vapor port and into the chamber. This air exits the instrument through the exhaust port and is recirculated through the simulator.

RESULTS

Three concentrations of acetone were tested: 10 mg%, 25 mg% and 50 mg%. At the 10 mg% level, the instrument always reported a value of 0 mg%. At the 25 mg% level, the instrument indicated an "INTERFERENT" and a test result of 0 mg% on 13 out of 15 tests. The other two tests were reported as 0 mg% with no "INTERFERENT" message. At the 50 mg% level, all results were reported as an "INTERFERENT" with a subsequent test result of 0 mg%.

The tests from the 100 mg% isopropanol simulator resulted in an "INTERFERENT" message each time with a subsequent test result (range 39 to 42 mg%; mean 41 mg%; SD 1.15). 20 mg% isopropanol resulted in values of either 0, 7 or 8 mg%. Any value less than 7 mg% was automatically reported as 0 mg% by the instrument. The combination of 50 mg% ethanol and 50 mg% isopropanol resulted in an "INTERFERENT" message each time with a subsequent test result (range 68 to 71 mg%; mean 70 mg%; SD 0.92). Testing with the simulator containing 100 mg% ethanol and 25 mg% isopropanol sometimes reported an "INTERFERENT" message with a subsequent test result and sometimes reported a test result only (range 108 to 112 mg%; mean 109 mg%; SD 1.13). The testing with the 75 mg% ethanol and 25 mg% isopropanol solution also reported an "INTERFERENT" message and a subsequent test result as well as a test result only (range 82 to 89 mg%; mean 84 mg%; SD 1.58).

100 mg% methanol produced an "INTERFERENT" message each time with no subsequent test result reported. The combination of 100 mg% ethanol and 25 mg% methanol resulted in a mean reported value of 122 mg% (range 120 to 124 mg%; SD 0.96) with no "INTERFERENT" message. The mean reported value for the 75 mg% ethanol and 25 mg% methanol was 97 mg% (range 95 to 99 mg%; SD 1.37). Again, no "INTERFERENT" message was displayed. At the level of 50 mg% ethanol and 50 mg% methanol, some of the results were reported as containing an interferent with no subsequent test result whereas most results were reported just as a test result with no interferent message (range 88 to 93 mg%; mean 91 mg%; SD 1.56).

The 25 mg% isopropanol/50 mg% acetone combination resulted in a mean result of 10 mg% (range 9 to 12 mg%; SD 1.13), the 50 mg% isopropanol/50 mg% acetone combination resulted in a mean result of 20 mg% (range 18 to 24 mg%; SD 1.40) and the 100 mg% ethanol/25 mg% acetone combination resulted in a mean result of 98 mg% (range 94 to 100 mg%; SD 1.68). For each of these combinations, an "INTERFERENT" message was always obtained followed by a test result. All of the above results are summarized in Table 1.

Solution Contents	Interferent Message?	Mean (mg%)
10 mg% acetone	No	0
25 mg% acetone	Yes (13 out of 15 times)	0+
50 mg% acetone	Yes	0
100 mg% isopropanol	Yes	41
100 mg% methanol	Yes	NR
20 mg% isopropanol	No	4
100 mg% alcohol/25 mg% isopropanol	Yes (5 out of 15 times)	109+
75 mg% alcohol/25 mg% isopropanol	Yes (8 out of 15 times)	84+
50 mg% alcohol/50 mg% isopropanol	Yes	70
100 mg% alcohol/25 mg% methanol	No	122
75 mg% alcohol/25 mg% methanol	No	97
50 mg% alcohol/50 mg% methanol	Yes (3 out of 15 times)	91+
25 mg% isopropanol/50 mg% acetone	Yes	10
50 mg% isopropanol/50 mg% acetone	Yes	20
100 mg% alcohol/25 mg% acetone	Yes	98

+: The mean was calculated from all values - those reported as containing an Interferent and those reported as apparent ethanol values

NR: Not reported

DISCUSSION

The risk of serious bodily harm or even death due to the consumption of methanol or isopropanol is well documented (Tephly, 1991; Adelson, 1974; Arena, 1978; Röe, 1982; McLean et al., 1980; Pappas et al., 1991; Alexander et al., 1982; Gloss and Solberg, 1970; Gloss, 1971). If a subject provides a breath sample into an Intoxilyzer 5000C and an "INTERFERENT" message is obtained, it is imperative that the police officer act quickly. While the instrument cannot tell what compound is producing the "Interferent" message, this message should cause the police officer to be concerned for the subject. The police officer should seek immediate medical assistance and advise the medical personnel of his/her suspicions.

The Criminal Code allows that when a police officer has "reasonable and probable grounds to believe, that by reason of any physical condition of the person, the person may be incapable of providing a sample of his breath or it would be impracticable to obtain a sample of breath" then blood samples can be demanded. In light of this, if the police officer takes a suspected impaired driver to the hospital in response to an "INTERFERENT" message on the Intoxilyzer 5000C, it may be possible for the police officer to demand a blood sample. Barring this, if the subject is willing, the police officer may be able to get the subject to provide a blood sample voluntarily. Another option that may be available to the police officer would be to seize, by means of a search warrant, any samples of blood that were taken for medical reasons or any hospital records that pertained to the hospital analysis of the blood. Any blood samples that are seized would be submitted to a forensic laboratory for analysis.

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