Studies in breath-alcohol analysis: biological factors

Area of Science:

• Forensic Science
• Analytical Chemistry
• Physiology

Background:

• Breath-alcohol analysis is crucial for law enforcement and clinical toxicology.
• Understanding biological variations is key to improving accuracy.
• Previous studies have not fully elucidated all influencing physiological factors.

Purpose of the Study:

• To investigate key biological factors impacting breath-alcohol analysis.
• To determine the optimal breath discard volume for accurate readings.
• To assess the influence of temperature and carbon dioxide on breath samples.

Main Methods:

• Measured end-expiratory temperature, forced vital capacity, and maximum exhalation in healthy subjects.
• Analyzed end-expiratory carbon dioxide levels.
• Monitored the dissipation rate of mouth alcohol with and without rinsing.
• Quantified water condensation in breath sampling devices at varying temperatures.

Main Results:

• End-expiratory temperatures ranged from 32.41-35.69°C (mean 34.53°C).
• 65-70% of breath must be discarded to reach the alveolar plateau.
• End-expiratory carbon dioxide levels varied from 3.5-8.3% (mean 6.52%).
• Mouth alcohol dissipated within 8-11 minutes.
• Water condensation in devices decreased with higher temperatures.

Conclusions:

• Discarding the initial portion of exhaled breath is critical for accurate breath-alcohol concentration.
• Physiological parameters like temperature and CO2 are important considerations.
• Device temperature significantly affects water condensation, potentially impacting sample integrity.