A Simple and Improved HPLC-PDA Method for Simultaneous Estimation of Fexofenadine and Pseudoephedrine in Extended Release Tablets by Response Surface Methodology

Table 4

ANOVA for 2³ full factorial design: responses are retention times of the drugs (PSU and FEX) and resolution ().

Source	DF	-value			value			Remark
		PSU	FEX		PSU	FEX
Model	5	98.06	74.95	48.87	0.0001	0.0001	0.0001	Significant
Linear	2	96.72	119.5	88.76	0.0001	0.0001	0.0001	Significant
Square	2	145.7	67.27	32.03	0.0001	0.0001	0.0001	Significant
Interaction	1	5.55	4.20	2.80	0.051	0.031	0.013	Significant
Lack-of-fit	3	0.77	0.324	0.490	0.569	0.295	0.120	Not significant