BAT Device Technology & Operation Principles 3 — Questions and Answers
Question 1: Mouth alcohol can falsely elevate a breath test result. Which observation during the 15–20 minute deprivation period most directly addresses this concern?
- Confirming the subject has not regurgitated, belched, or introduced any substance into the mouth (Correct answer)
- Measuring the subject's salivary alcohol content with a test strip
- Verifying the subject's last meal was consumed more than two hours prior
- Checking that no tobacco products were used within 24 hours
Correct answer: Confirming the subject has not regurgitated, belched, or introduced any substance into the mouth
The observation period is designed to detect any event — vomiting, belching, or oral intake — that could introduce residual mouth alcohol and inflate the breath alcohol reading.
Question 2: How does ambient temperature affect the partition ratio assumption used in breath testing devices?
- Higher ambient temperatures lower the 2100:1 blood-to-breath partition ratio, overstating BAC
- Temperature has no effect because the sample chamber is thermostated independently
- Lower ambient temperatures cause ethanol to condense in the sample chamber, understating BAC
- Both B and C may occur depending on whether the chamber heater is functioning (Correct answer)
Correct answer: Both B and C may occur depending on whether the chamber heater is functioning
If the chamber heater fails, low ambient temperatures can cause condensation (understating BAC), while a malfunctioning thermostat at high temperatures may shift the partition ratio assumption and overstate BAC.
Question 3: What distinguishes an evidential breath testing instrument from a preliminary alcohol screening (PAS) device?
- Evidential devices use fuel cells; PAS devices exclusively use semiconductor sensors
- Evidential devices are approved for court-admissible results and require operator certification; PAS devices are used for probable cause screening only (Correct answer)
- Evidential devices require a blood draw confirmation; PAS devices do not
- Evidential devices measure blood alcohol directly; PAS devices estimate from saliva
Correct answer: Evidential devices are approved for court-admissible results and require operator certification; PAS devices are used for probable cause screening only
Evidential instruments (e.g., Intoxilyzer, Datamaster) meet strict regulatory standards for accuracy and are used to produce legally admissible BAC results, whereas PAS devices serve only as field screening tools.
Question 4: A subject with uncontrolled diabetes has elevated ketones (acetone) in breath. How do modern evidential IR devices address this potential interference?
- They use a wavelength specific to acetone to subtract its contribution from the ethanol reading (Correct answer)
- They flag the test as invalid whenever any interfering compound is detected
- They require the operator to manually enter the subject's medical condition
- They increase the observation period to 30 minutes for diabetic subjects
Correct answer: They use a wavelength specific to acetone to subtract its contribution from the ethanol reading
Modern IR analyzers sample multiple wavelengths or use an acetone-specific channel to detect and subtract acetone interference, preventing a false-positive ethanol reading.
Question 5: On the Intoxilyzer 8000, what is the significance of the 'invalid sample' result during a breath test sequence?
- The subject's BAC exceeded the device's upper measurement limit
- The device detected that the breath sample did not meet volume or flow criteria for a valid alveolar sample (Correct answer)
- The simulator solution temperature was outside the acceptable range during the test
- The device's internal memory was full and could not store the result
Correct answer: The device detected that the breath sample did not meet volume or flow criteria for a valid alveolar sample
An 'invalid sample' result indicates the subject's breath delivery did not satisfy the instrument's criteria (minimum volume, flow pattern) needed to ensure the sample represents deep lung air.
Question 6: In a fuel cell instrument, what role does the platinum black catalyst play?
- It acts as the electrolyte, transferring protons between anode and cathode
- It provides a high-surface-area site that catalyzes ethanol oxidation without being consumed (Correct answer)
- It amplifies the electrical current signal before it reaches the measurement circuit
- It filters out interferents by selectively binding non-ethanol compounds
Correct answer: It provides a high-surface-area site that catalyzes ethanol oxidation without being consumed
Platinum black serves as a heterogeneous catalyst with very high surface area, accelerating ethanol oxidation at the electrode surface while remaining unchanged in the reaction.
Question 7: Which of the following best describes the 'slope back' detector used in some breath analyzers?
- A sensor that detects the falling portion of the breath curve to confirm alveolar plateau has been reached (Correct answer)
- A pressure transducer that measures residual breath volume in the lungs after exhalation
- A temperature probe that monitors the cooling slope of the sample chamber after the test
- A circuit that detects the declining current slope as the fuel cell approaches saturation
Correct answer: A sensor that detects the falling portion of the breath curve to confirm alveolar plateau has been reached
The slope back detector analyzes the tail of the exhaled breath curve; when the alcohol concentration plateaus and begins to level off, it confirms the alveolar air plateau has been captured.
BAT Device Technology & Operation Principles 3
Mouth alcohol can falsely elevate a breath test result.
Which observation during the 15–20 minute deprivation period most directly addresses this concern?