Figure 3: First derivative of ratio spectra of 25 μg mL-1 of 10 μg mL-1 of Paracetamol (―), 8 μg mL-1 of Diphenhydramine Hydrochloride (- - -) and 10 μg mL-1 P-aminophenol (…..) using 10 μg mL-1 of Para-aminophenol as a divisor and methanol as a solvent.