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Updated: Jun 28, 2026

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions
Published on: October 2, 2018
Fluorometric reactions of purines and determination of caffeine
1Meiji College of Pharmacy, 1-35-23 Nozawa, Setagaya-ku, Tokyo 154, Japan.
Abstract:
Two new spot-tests for purines are described together with a new sensitive determination of caffeine. The spot tests involve a fluorometric reaction with 4,5-dimethyl-o-phenylenediamine after oxidation with N-bromosuccinimide. Caffeine treated in this manner exhibits a blue fluorescence with excitation maxima at 340 and 390 nm, and an emission maximum at 480 nm. The fluorometric reaction may be used to determine caffeine in the range 0.01-10, mug/ml with a relative standard deviation of 0.9% for 0.1 mug/ml caffeine. The method has been used to determine caffeine in cough syrups.

