Determination of Thiamazole in Pharmaceutical Samples Using Sodium Nitroprusside as the Chromogenic Agent
The experiment indicated that a green product could be formed by the reaction of thiamazole and sodium ntroprusside,when NaOH was 6.7×10-3 mol/L in the solution,and temperacture and reaction time were 0 ℃ and 30 min,respectively.The stoichimetric ratio of the green product was 1∶1.The maximal absorption wavelength of the product was 610 nm,e610=1.5×103 L/(mol·cm).Good linear relationship was obtained between the absorbance and the concentration of thiamazole in the range of 4.8-48 mg/L.The equation of the linear regression was A=-0.0617+0.01329C(mg/L),with a linear correlation coefficient of 0.9991.The detection limit was 0.47 mg/L,and the relative standard deviation was 0.2%.The method has been successfully applied to the determination of thiamazole in tablets with a average recovery of 97.2%.