Abstract
The well known Hurexide reaction for purine bases was modified and optimized for the quantification of caffeine in crude drugs, refreshing drinks and pharmaceuticals. The method was also applied for the detection and assay of caffeine in mixtures of illegal opiate samples. It was also applied to assay theobromine and theophylline alongside with caffeine in their natural and synthretic mixtures after a simple separating procedure depending on their different basicities.