Parameters Derivative method (PAR) 1DD method (DPH) Densitometric method PAR DPH PAP Range (μg mL-1) 2-12 5-18 0.4-1.6 3-12 0.4-1.6 Linearity Slope Intercept Correlation coefficient (r) 0.0373 0.0074 0.9997 0.1105 0.0963 0.9998 0.2675 0.0782 0.9997 0.0651 0.1561 0.9999 0.3151 0.1206 0.9998 Accuracy (mean ± SD) 99.94 ± 1.33 99.70 ± 0.99 100.00 ± 0.93 100.35 ± 0.86 100.10 ± 0.91 Selectivity 100.48 ± 1.48 98.62 ± 0.17 99.50 ± 1.53 99.30 ± 1.45 100.25 ± 0.98 Precision (RSD%) Repeatability* Intermediate precision* 0.72 0.82 0.25 0.40 0.44 0.52 0.57 0.73 0.57 0.65 * The intraday precision (n=3), average of three different concentrations repeated three times within day. The interday precision (n=3), average of three different concentrations repeated three times in three successive days.

Table 6: Results of assay validation parameters of the proposed methods for determination of Paracetamol, Diphenhydramine Hydrochloride and P-aminophenol.