title: Determination of thiamazole in pharmaceutical samples by phosphorus molybdenum blue spectrophotometry.
abstract: A novel method is established to determine thiamazole by phosphorus molybdenum blue spectrophotometry. The experiment indicates that PO(4)(3-) reacts with Mo(7)O(24)(6-) in 0.30mol/L H(2)SO(4) solution to form a product with phosphorus-molybdenum heteropoly acid ([H(2)PMo(12)O(40)](-)). Then [H(2)PMo(12)O(40)](-) is deoxidized to form phosphorus molybdenum blue (H(3)PO(4)·10MoO(3)·Mo(2)O(5)) by thiamazole. The amount of thiamazole can be determined based on the absorbance of phosphorus molybdenum blue (λ(max)=710nm). A good linear relationship is obtained between the absorbance and the concentration of thiamazole in the range of 0.035-70μg/mL. The equation of the linear regression is A=0.03384+0.00834c (μg/mL), with a linear correlation coefficient of 0.9990. The apparent molar absorption coefficient is 1.0×10(3)L/(molcm). The method has been successfully applied to the determination of thiamazole in pharmaceutical samples with satisfactory results, and recoveries are in the range of 99.6-100.6%.
authors.affiliation: College of Chemistry and Environmental Science, Henan Normal University, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007, PR China.
authors.forename: Jing'e
authors.initials: J
authors.lastname: Huo
authors.forename: Quanmin
authors.initials: Q
authors.lastname: Li
mesh_terms: D013956:Antithyroid Agents / Q000032:analysis*; D008713:Methimazole / Q000032:analysis*; D008982:Molybdenum / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000379:methods*
chemical_list: D013956:Antithyroid Agents; D004364:Pharmaceutical Preparations; C017541:molybdenum blue; D008713:Methimazole; D008982:Molybdenum