OPTIMIZATION OF A UV-VIS SPECTROMETRIC METHOD FOR CAFFEINE ANALYSIS IN TEA, COFFEE AND OTHER BEVERAGES

A method has been developed and validated for the determination of caffeine in tea, coffee and other beverages by UV-VIS spectrometry. A linear calibration curve was generated with caffeine concentration ranging from 3 mg∙L-1 to 18 mg∙L-1. The procedure developed provides a 0.85 mg∙L-1 detection limit of caffeine, respectively 1.52 mg∙L-1 quantification limit and the relative standard deviation (RSD) was less than 0.05 % for independent measurement. The developed method was sensitive/specific and robust. Caffeine in tea infusions was found to be dependent on infusion time, the longer of the infusion time and the higher of the caffeine concentrations in tea infusions