Table 1: Analytical parameters.

EPI HPC  nm 405 402 Beer’s law limit (μg mL−1) 2.00–22.00 20.00–120.00 Molar absorptivity (L mol−1 cm−1) 0.51 × 104 0.10 × 104 Sandell’s sensitivity (μg cm−2) 0.027 0.134 Regression equation* Slope () 0.0336 0.0064 Intercept () 0.022 0.018 Correlation coefficient () 0.9910 0.9979 Limit of Detection** (μg mL−1) 1.500 5.150 Limit of Quantitation** (μg mL−1) 4.545 15.620

* is the absorbance and is the concentration in μg mL−1. ** Calculated using ICH guidelines.