溴甲酚绿褪色光度法测定药物中的乌拉地尔

Determination of urapidil in drugs by fading spectrophotometry with bromocresol green

研究了乌拉地尔与溴甲酚绿的反应条件、共存物质影响及吸收光谱特征,建立了测定药物中乌拉地尔含量的多波长褪色分光光度法。乌拉地尔与溴甲酚绿在pH 8.63的Tris-盐酸介质中反应在可见光区生成具有3个负吸收峰的二元离子缔合物,3个负吸收峰波长分别位于652 nm、568 nm和396 nm,它们的表观摩尔吸光系数(κ)分别为2.76×104L/(mol·cm)(652 nm)、2.32×104L/(mol·cm)(568 nm)和1.10×104L/(mol·cm)(396 nm)。当用双波长或三波长叠加负吸收光谱法测定时,表观摩尔吸光系数分别可达5.08×104L/(mol·cm)(652 nm+568 nm)和6.19×104L/(mol·cm)(652 nm+568 nm+396 nm)。它们的线性范围均为0~4.2 mg·L-1,服从朗伯-比尔定律。将652 nm处的单波长法用于市售乌拉地尔药物中乌拉地尔含量分析,加标回收率(n=6)为98.27%~102.7%,相对标准偏差RSD(n=6)为2.4%~2.5%。

The reaction conditions of urapidil and bromocresol green,the influence of the coexisting substances and the characteristics of absorption spectrum were studied.A new multi-wavelength fading spectrophotometry for the determination of urapidil in drugs was established.In a Tris-hydrochloric acid media of pH 8.63,urapidil reacts with bromocresol green to form binary ion association complexes with three negative absorption peak in the visible area.The three negative absorption peaks were at652 nm,568 nm and 396 nmrespectively.Their apparent molar absorptivity(κ)were2.76×10^4L/(mol·cm)(652 nm)and 2.32×10^4 L/(mol·cm)(568 nm)and 1.10×10^4 L/(mol·cm)(396 nm),respectively.When the double wavelength or three-wavelength superposition negative absorption spectrometry were used to determine the concentrations of urapidil,and their apparent molar absorptivity(κ)can be achieved 5.08×10 4 L/(mol·cm)(652 nm+568 nm)and 6.19×10^4 L/(mol·cm)(652 nm+568 nm+396 nm),respectively.The urapidil obeys Lombard Beer’s law in definite mass concentration range of 0 to 4.2 mg·L^-1.The method was applied to determine the content of urapidil in commercially available urapidil medicine with the standard addition recovery(n=6)and RSD(n=6)found were in the ranges of 98.27%-102.7%and 2.4%-2.5%respectively.