Kinetic determination of caffeine in drug formulations

Abstract EN

Two simple and accurate kinetic methods, the fixed time and the fixed concentration methods, for the determination of caffeine were described.

The two methods involve the use of 3.20xl0"3M cerium(iv) solution and 8.0x10" M sulfuric acid.

Reaction rates were followed at 405 nm; absorbance measurements for the fixed time method were taken at 350 s; and the following calibration equation was used for calculating unknown concentrations of caffeine.

A = 2.31 -3.55 xlO"3C For the fixed concentration method, time was measured at a fixed absorbance of 1.70 and the following calibration equation was used: \jt = -1.25 x 10"3 + 2.48 x 10”5 C The two methods were applied to the determination of caffeine in proprietary drugs, interferences were studied, and a statistical comparison with the results obtained by the official BP method was made.