For the first time, the results of the present investigation allow a survey of post-offence alcohol drinking claims by means of characteristic flavourings in blood/scrum samples. For that purpose, the beverage flavouring agents including anethole, eugenol, carvone, menthone, isomenthone, neomenthol and menthol were selected from spirits. These substances are mainly found in spirits being poor in congeners, in which the validation of a post offence drinking claim is impeded by conventional congener analysis. The investigation of flavouring agents provides a considerable improvement in the validation of post offence drinking claims. To detect these flavourings in the serum a sensitive analytical method was developed. From the results of experiments, the metabolism and pharmacokinetics of these compounds were examined. Formulas being similar to the "Bonteformulas" were created to determine the calculation values of the kinetics. Finally, an error estimate has been carried out. The analysis method was proved to be practicable because these flavourings actually were detected in numerous blood/serum samples after consumption of appropriate spirits. In cases where no relevant flavouring spirits were consumed, no flavourings could be detected.