VALIDATION OF AN ANALYTICAL METHOD FOR THE SIMULTANEOUS DETERMINATION OF PARACETAMOL AND CAFFEINE IN PRESENT OF CODEINE IN DRUGS BY DERIVATIVE UV SPECTROPHOTOMETRY

Abstract

The analytical method for determination of paracetamol (PAR) and caffeine (CAF) in the presence of codeine (COD) in pharmaceutical samples by UV-VIS derivative spectroscopy was validated. The second derivative spectrum was selected and the wavelengths of 236 nm and 292 nm were the optimal wavelengths for PAR and CAF analysis. The linear ranges for determining PAR and COD were 0.5 – 40.0 and 0.15 – 40.0 mg/L, with R² = 0.9974 and 0.9975, respectively. LODs, LOQs were found and they were 0.07 mg/L, 0.23 mg/L and 0.10 mg/L, 0.33 mg/L for PAR and CAF, respectively. The method had good repeatability with RSDr < 2% for both standard and sample, and recovery efficiencies for both substances were in the range of 89 – 109%. Research carried out to evaluate the interaction between substances on the analytical results and showed that the method was completely consistent with the ratio of drug content commonly. The method was applied to analyze pharmaceutical samples in Vietnam and compared with the results at the Center for Analytical Services and Experimentation of Ho Chi Minh City (CASE).