SPECTROPHOTOMETRIC TITRATIONS OF CAFFEINE, THEOBROMINE AND THEOPHYLLINE IN NONAQUEOUS SOLVENTS

Spectrophotometric titrations of caffeine, theobromine and theophylline in nonaqueous solvents were studied and the proposed analytical procedure is outlined below: Dissolve about 50 mg of sample in 50 ml of glacial acetic acid, titrate the solution with standard acetous perchloric acid solution, at wave length of 609 mμ, using malachite green as indicator. Take absorbancy readings at every convenient intervals, until at least three readings are taken beyond the end point. The end point is then determined by plotting the absorbancy against volume of acetous perchloric acid for caffeine and theophylline, and percentage transmission against volume of acetous perchloric acid solution for theobromine. The relative error of this method is±0.5% in macroscale, and is up to ±1.5% in semimicro and micro scales.