Simultaneous kinetic determination of paracetamol and caffeine by H-point standard addition method

Abstract

A very simple and selective spectrophotometric method for simultaneous kinetic determination of paracetamol and caffeine using H-point standard addition method (HPSAM) was described. The method was based on difference in the rate of oxidation of these compounds with Cu(II)-neocuproine system and formation of Cu(I)–neocuproine complex which monitored at 453 nm by spectrophotometer at pH 5.0 in the presence of surfactant sodium dodecyl sulfate (SDS). Experimental conditions such as pH, reagent concentrations, ionic strength and temperature were optimized. Paracetamol and caffeine can be determined in the range of 1.5 - 7.0 and 0.1-3.0 μg ml-1 respectively. The proposed method was successfully applied to the simultaneous determination of paracetamol and caffeine in pharmaceutical samples and satisfactory results were obtained. Key words: Paracetamol, caffeine, neocuproine, determination, HPSAM.