The technical requirements for future evidential breath testing in Germany have been published recently in a draft of the German standard DIN/VDE 0405. In addition to the OIML specifications several requirements had to be added to achieve legal and technical acceptance. The most important are: two consecutive breath tests for mouth alcohol detection; measurement of the endexpiratorial breath temperature to compensate for changes in breath alcohol concentration due to the subject's body temperature and breathing technique; a sex and age dependent minimum blowing volume; and verification of the calibration by including two independent measuring systems with mutual control. Up to now no available instruments fulfil these requirements. We present a detailed description of a breathtesting instrument comprising two independent analytical systems (infrared and electrochemical) and means for breath temperature measurement. Furthermore, results from field and laboratory tests are given. Our data show a very good correlation between blood and breath alcohol concentration and show that breath temperature measurement considerably improves the performance of an evidential breath tester. (A)
Samenvatting