Fading spectrophotometric method for determination of sodium aescinate with ethyl violet

In pH 4.1 BR buffer medium,ethyl violet(EV) reacts with sodium aescinate(SA) to form an ion-association complex.The maximum fading wavelength is at 594 nm.The fading intensity is proportional to the concentration of sodium aescinate.The concentration of sodium aescinate in the range of 0.15～35.0 μg/mL obeys beer′s law.The correlation coefficient is 0.9995,the molar absorptivity is 2.5×104 L·mol-1·cm-1 and the detection limit is 45.8 ng/mL.The method has high sensitivity and low detection limit,and has been applied to the determination of sodium aescinate in tablets samples and urine samples with satisfactory results.