Development and Validation of an HPLC-DAD Method to Quantify Caffeine in Time-release Dosage Forms.

Controlled release caffeine dosage forms are applied in order improve bioavailability to enhance ergogenic and thermogenic actions. High-performance liquid chromatographic separation was achieved using a C18 reversed phase column, a binary mixture of 0.1 % phosphoric acid and acetonitrile with a flow rate of 0.8 ml/min. UV detection was at 220 nm. Water produced the best extraction efficiency in comparison with other solvents. Retention time observed for caffeine was 4.5 min. The method is selective, reliable, reproducible with a linear range over 1.0-20.0 µg/ml of caffeine (r>0.9987). The proposed method allows to distinguish caffeine from sibutramine, p-octopamine, p-synephrine, tyramine and hordenine. The limit of detection and limit of quantifications were 10 and 30 ng/ml, respectively. The proposed method could be used for the routine analysis of caffeine in time-release dietary supplements. [ABSTRACT FROM AUTHOR]