Principle
The alcohol concentration in oral fluid (mainly saliva) mirrors that in blood. Mouth alcohol, of course, must be absent; this is why breathtesting and oral fluid testing are carried out after a period of time (at least 15 minutes) has elapsed since the last drink.
Analysis
Simple screening tests for alcohol in oral fluid can be carried out using the Alcoscreen (Chematics) system. A testing stick is placed in the mouth for a few seconds and a colour change denotes the presence of alcohol. Normally a confirmation test is necessary to show conclusively that alcohol is present - either breathtesting or urine testing may be used for this purpose.
