Difference spectrophotometric andRP-HPLCmethods for simultaneous determination of aceclofenac and paracetamol in combined tablet dosage form

A simple difference spectrophotometricmethod has been developed for the estimation of aceclofenac and paracetamol frompharmaceutical dosage form. The change in pH altered the absorption spectra of aceclofenac and paracetamol. Differential spectrumof paracetamol and aceclofenac in alkaline and acidic solution showedmaximumabsorbance at 267 nmand 246 nm and minimum at 232 nm and 276 nm respectively. Measurement of absorbance was carried out at zero-crossing wavelength 247 nmfor paracetamol and 256.7nm for aceclofenac. BeerÂ’s law was valid in the concentration range of 1-20i­g/ml for aceclofenac and 1-50 µg/ml for paracetamol. This method was validated for precision (n=6) and accuracy (100.15 i‚±0.761 %) and (99.73i‚±0.436 %) respectively (n=3) at each level. The reverse phase high performance liquid chromatographic (RP-HPLC), has been developed and validated for the simultaneous estimation of paracetamol (PARA) and aceclofenac (ACE) in tablet dosage form.WatersC18 Octadecyl Silane (ODS) column (250 i‚´ 4.6mmi. d., 5i­ particle size) in isocraticmodewas used. The mobile phase used was acetonitrile: 50 mM sodium dihydrogen phosphate (50:50) v/v, pH3.0 ± 0.1 with orthophosphoric acid. The flow rate was 1.5 mL per minute and eluent was monitored at 276 nm. The retention times of PARAand ACE were found to be 1.92 min and 9.28 min respectively. The linearity for paracetamol and aceclofenac were in the range of 5 - 50i­g /mL and 1.0 - 10i­g /mL respectively (n=6). Percentage recoveries obtained for paracetamol and aceclofenac were 100.7% and 100.4 % respectively. The relative standard deviationwas found to be 1.78%and 1.80%for paracetamol and aceclofenac in triplicate analysis. Thus the proposed methods are precise, accurate, selective and rapid for simultaneous estimation of paracetamol and aceclofenac in tablet formulation.