Abstract
A simple, rapid, selective and sensitive kinetic method for the determination of Paracetamol utilizing sequential injection analysis (SIA) technique was explored. The method was based upon comprehensive kinetic investigation of oxidation reaction of paracetamol with potassium permanganate in sulphuric acid media. The absorbance decrease of permanganate was measured at the wavelength 526 nm to monitor the reaction kinetics. The reaction orders with respect to the concentration of sulphuric acid, permanganate and paracetamol were found to be inverse one (-1), positive one (+1), and positive one (+1), respectively. The activation energy was examined and the reaction mechanism was postulated. The fixed time kinetic approach was used for the determination of the drug. The calibration equation "A = 0.0038C + 0.1209", with 0.9931 correlation coefficient (r) was found to be linear for paracetamol concentration ranging between 6.61 × 10-5 to 1.32 × 10-3 mol l-1 at the fixed time of 70 s at room temperature. This equation was obtained when injecting 35 μl of 1.0 mol l-1 H2SO4, 30 μl of 2.0 × 10-3 mol l-1 potassium permanganate, 20 μl of paracetamol and 25 μl water and by adjusting the flow rate at 25 μl s-1. The newly adopted method was applied for the determination of paracetamol in dosage forms of tablets and capsules containing other drugs. No interference was observed neither from the other drugs of diphenylamine hydrochloride, chloroxazone and pseudophedrine hydrochloride nor from excipients. The proposed SIA kinetic method was found to be accurate and repeatable when the results were statistically compared with the results obtained by the BP standard method.
