Development of Control Material for Exhaled Breath-Alcohol Testing and its Application

Area of Science:

• Forensic Science
• Analytical Chemistry
• Metrology

Background:

• Breath analyser tests are vital for detecting alcohol intoxication and prosecuting traffic violators.
• Current calibration and maintenance practices for breath analysers lack sufficient quality control, potentially leading to inaccurate results.
• Calibration deterioration is a significant concern affecting the reliability of breath-alcohol testing.

Purpose of the Study:

• To develop and evaluate control materials for breath-alcohol testing.
• To assess the uncertainty associated with these control materials.
• To enhance the quality assurance of breath analyser calibration at the Bangkok Metropolitan Police Station.

Main Methods:

• Ethyl alcohol (Certified Reference Material grade) was diluted to three concentrations: 28, 67, and 134 mg/dL.
• Concentrations were determined using headspace gas chromatography.
• Uncertainty was calculated according to ISO Guide 35:2017, with values of ±4.97%, ±4.29%, and ±2.72% for each concentration.

Main Results:

• The developed control materials exhibited total error percentages of 4.97%, 4.29%, and 2.72% for the respective concentrations.
• Measurements were taken using 70 breath-alcohol analysers from the Bangkok Metropolitan Police Station.
• The evaluated uncertainties were ±1.3925 mg/dL, ±2.8736 mg/dL, and ±1.8231 mg/dL.

Conclusions:

• The developed control materials are suitable for quality assurance and standards testing in breath-alcohol analysis.
• These materials can contribute to ensuring the accuracy and reliability of future breath-alcohol testing.
• Implementation of these control materials can improve the overall integrity of forensic alcohol testing.