The response of the Intoxilyzer 5000 to five potential interfering substances

Area of Science:

• Forensic Science
• Analytical Chemistry
• Toxicology

Background:

• Evidential infrared breath testing devices are crucial for law enforcement.
• The Intoxilyzer-5000 is a widely used infrared breath testing instrument.
• Potential for interfering substances on human breath to affect device accuracy is a concern.

Purpose of the Study:

• To investigate vapor phase interferents on human breath.
• To assess the capability of these interferents to induce false-positive ethanol readings on the Intoxilyzer-5000.
• To quantify the relationship between interferent concentration and false-positive ethanol readout.

Main Methods:

• Preparation and validation of vapor standards for potential interferents.
• Introduction of vapor standards to the Intoxilyzer-5000 using a dynamic flow double-bubbler system.
• Selection of interferents based on infrared signatures and availability (toluene, xylenes, methanol, isopropanol).

Main Results:

• All tested compounds (toluene, m-xylene, o-xylene, methanol, isopropanol) reproducibly induced false-positive ethanol readings.
• Precise least-squares equations were derived to describe expected ethanol readouts for given blood concentrations of these solvents.
• The study established the potential for interference based on toxicological significance, prevalence, and instrument trigger points.

Conclusions:

• Common volatile organic compounds found in human breath can interfere with infrared ethanol breath testing.
• The Intoxilyzer-5000 is susceptible to false-positive ethanol results from specific interferents.
• Accurate breath alcohol analysis requires consideration of potential interferents and their quantification.