在pH 7.93的弱碱性Tris-盐酸介质中，乌拉地尔与偶氮胂Ⅲ反应生成具有1个明显正吸收峰和1个明显负吸收峰的二元离子缔合物，最大正吸收峰位于629 nm，最大负吸收峰位于521 nm，其表观摩尔吸光系数（κ）分别为2.27×10⁴ L/（mol·cm）（629 nm）和1.81×10⁴ L/（mol·cm）（521 nm），当采用双波长可见吸收光谱法测定时，其表观摩尔吸光系数（κ）可达4.08×10⁴ L/（mol·cm），线性范围均为0.01~4.2 mg/L，服从朗伯-比尔定律，据此建立了测定乌拉地尔的双波长可见吸收光谱法。结果表明，该方法可用于市售乌拉地尔片剂和针剂药物中乌拉地尔含量的测定。

In weak alkaline Tris-hydrochloric acid media with a pH value of 7.93,urapidil reacts with arsenazo Ⅲ to form binary ion association complexes with an obvious positive absorption peak and an obvious negative absorption peak.The maximum positive and negative absorption peaks locate at 629 nm and 521 nm,respectively,and their apparent molar absorptivity (κ) are 2.27×10⁴ L/(mol·cm) and 1.81×10⁴ L/(mol·cm) respectively.When the dual wavelength visible absorption spectrometry is used to determine the concentration of urapidil,its apparent molar absorptivity (κ) can achieve 4.08×10⁴ L/(mol·cm).The linear range is always in the 0.01-4.2 mg·L^-1,which obeys to Lambert-Beer's law.On this basis,a dual wavelength visible absorption spectroscopy method is established for the determination of urapidil.The satisfactory results can be obtained when this method is applied to determine the content of urapidil in commercially available urapidil tablet and injection medicines.

庞向东(1962-),男,理学学士,副教授,研究方向为分子光谱分析,cspxdfxsch123456@163.com