Evaluation of breath alcohol instruments. II. In vivo experiments with alcolmeter pocket model

Area of Science:

• Forensic Science
• Analytical Chemistry
• Pharmacokinetics

Background:

• Breath alcohol instruments are crucial for law enforcement and clinical monitoring.
• Accurate measurement of blood alcohol content (BAC) is vital for public safety and medical assessment.
• The Alcolmeter Pocket Model is a portable device for estimating BAC.

Purpose of the Study:

• To evaluate the precision and accuracy of the Alcolmeter Pocket Model breath alcohol instrument.
• To assess the instrument's performance under controlled conditions with human subjects.
• To determine the reliability of breath alcohol measurements during different phases of ethanol metabolism.

Main Methods:

• Experiments conducted with human subjects under controlled conditions.
• Breath samples analyzed for ethanol concentration using the Alcolmeter Pocket Model.
• Comparison of instrument readings with actual ethanol levels during absorption and elimination phases.
• Statistical analysis of standard deviations and coefficients of variation.

Main Results:

• The Alcolmeter consistently showed zero response for alcohol-free breath samples.
• Standard deviations for ethanol determination were +/-0.0722 mg/ml during absorption and +/-0.416 mg/ml during elimination.
• Increased standard deviation during elimination phase, with a 9.9% coefficient of variation at 0.420 mg/ml.
• Blood alcohol estimates were higher during absorption and lower during elimination when using a 2100:1 ratio.

Conclusions:

• The Alcolmeter Pocket Model demonstrates acceptable precision for alcohol-free samples.
• Instrument accuracy is affected by the phase of ethanol kinetics (absorption vs. elimination).
• Calibration with a constant blood-breath ratio may lead to significant underestimation during ethanol elimination at critical BAC levels.