Preparation of calibration gas mixtures for the measurement of breath alcohol concentration.

Calibration gas mixtures for breath alcohol measuring techniques need to have a defined ethanol concentration in water-saturated air. For the calibration of evidential breath analysers in Germany, these gases are prepared at the Physikalisch-Technische Bundesanstalt according to the saturation method. The ethanol concentration is calculated via the air-liquid partition ratios of the air-water-ethanol substance system.