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

Figure 3

Overlaid contour plot of the responses and the design space: (min) and (min) are the retention time of FEX and PSU in minute. Solid lines indicated the desired lower limit and broken lines indicated the desired upper limit of each response.