Ethanol depletion dynamics in non-recirculating system breath alcohol simulators.

Area of Science:

• Forensic Science
• Analytical Chemistry
• Instrument Calibration

Background:

• Breath alcohol simulators use heated ethanol solutions to mimic human breath for calibrating alcohol testing devices.
• Repeated sampling of simulator vapor leads to ethanol concentration depletion at an unquantified rate.

Purpose of the Study:

• To quantify and understand ethanol depletion in non-recirculating breath alcohol simulators.
• To determine the relationship between air flow rate, initial concentration, and ethanol depletion.
• To develop a predictive model for ethanol concentration after repeated testing.

Main Methods:

• Breath alcohol simulators were filled with reference solutions.
• Air was pumped through simulators at varying flow rates (11, 16, 21 L/min) and concentrations (0.02–0.40 BrAC).
• Ethanol concentration depletion was measured using infrared spectroscopy.

Main Results:

• Ethanol depletion directly correlated with the total volume of air passed through the system (r > -0.95).
• Higher initial ethanol concentrations resulted in increased depletion rates.
• A predictive equation for ethanol concentration after repeated testing was developed.

Conclusions:

• Ethanol depletion in non-recirculating simulators is predictable based on air volume and initial concentration.
• Findings support the development of more accurate calibration protocols for breath alcohol testing instruments.
• Understanding depletion rates is crucial for maintaining the reliability of evidential breath alcohol measurements.