Simultaneous UV-Spectrophotometric Estimation of Paracetamol and Guaiphenesin by First Order derivative Method in Combined Dosage Form

The objective of the study was to develop a simple, accurate, precise and rapid a UV spectrophotometric i.e. first order derivative method for the determination of paracetamol and guaiphenesin in combined dosage form i.e. tablets by using methanol as a solvent. The method was further validated by ICH guidelines. The proposed first order derivative method involves the measurement of absorbance of one drug at zero crossing point of other; hence wavelengths 230 nm and 263 nm were selected for the estimation of paracetamol and guaiphenesin respectively. The linearity of the proposed method was found in the concentration range of 1 to 10 μg/ml (r²= 0.9998) for paracetamol and 10 to 100 μg/ml (r²= 0.9993) for guaiphenesin respectively. The percentage mean recovery was found to be 99.955% for paracetamol and 99.88% for guaiphenesin respectively. The method was also statistically validated for its linearity, accuracy and precision. Both intra and inter day variations showed less percentage (%) RSD values indicating high grade of precision of this method.