The effect of the concentration of the dye on the
intensity of the color developed at the selected wavelength
and constant drug concentration was tested
using different volumes of MO (0.5 - 4.0 mL). It was
observed that 0.5 mL of 0.2% (w/v) MO was necessary
for maximum color development of the ion-pair complex.
Above this volume, the absorbance remained constant.