H-Point Standard Additions method for the simultaneous determination of Paracetamol and Chlorzoxazone in Tablets using addition of both analytes and absorbance increment (?A)

The suitability of H-point standard additions method (HPSAM) to resolve of overlapping spectra corresponding to the paracetamol and chlorzoxazone was verified. The results showed that the H-point standard additions method with simultaneous addition of both analytes utilizing absorbance increment is suitable for the simultaneous determination of paracetamol and chlorzoxazone. The results of applying the H-point standard additions method showed that the two drugs could be determined simultaneously with the concentration ratios of paracetamol to chlorzoxazone varying from 1:2 to 2:1 in the mixed samples. In addition the means of the calculated RSD (%) were 1.40 and 1.92 in synthetic mixtures with 1.29 and 1.68 in dosage form for paracetamol and chlorzoxazone, respectively.