甲基绿褪色光度法测定琥乙红霉素

Fading spectrophotometric determination of erythromycin ethylsuccinate with methyl green

在pH7．8的磷酸盐缓冲溶液中，琥乙红霉素和甲基绿在50℃下可以反应形成稳定的离子缔合物。冷却至室温后以水做参比测定体系的吸收光谱，发现琥乙红霉素溶液在550～670nm几乎无吸收，甲基绿在此区域有强烈的吸收，甲基绿与琥乙红霉素生成的离子缔合物的吸光度与甲基绿相比有明显降低，最大褪色波长在634nm附近，且吸光度变化M与琥乙红霉素的浓度成正比。琥乙红霉素的质量浓度在0．0009～0．1530mg／mL范围内服从Beer定律，线性回归方程为：A=-3．037p＋0．0355，r=0．9995；对10．00mL5．0×10^-3mg／mL琥乙红霉素测定6次，RSD=0。6％，在634nm测得8：6．19×10^4L·nol^-1·cm^-1。研究了琥乙红霉素一甲基绿反应体系的光谱特性、反应的影响因素、共存物质的影响，做了反应的条件优化实验，对所建立的方法进行了一些初步的分析应用。在实验基础上，建立了测定琥乙红霉素的褪色分光光度法，检出限为0．21μg／mL，可用于琥乙红霉素片中琥乙红霉素含量的测定。

In pH 7.8 phosphate and hydrophosphate buffer solution, erythromycin ethylsuccinate reacts with methyl green to form a complex at 50 ℃. The solution was cooled to room temperature, and its absorption spectrum was recorded against the water. Under the optimum condition, erythromycin ethylsuccinate solution showed weak absorbance in 550 ~ 670nm, methyl green solution showed absorption spectra obviously, but the intensity of absorbance decreased obviously when erythromycin ethylsuccinate coexisted with muchyl green to form the complex, the fading absorbance intensity AA （absorbance, against the reagent blank） of the complex was measured at its maximum absorption wavelength of 634nm, and calibration curve of AA against concentration of erythromycin ethylsuccinate was obtained. Beer＇ s law is obeyed in the range of 0. 0009 ~ 0. 1530 mg/mL for erythomycin ethylsuccinate. Linear regression equation is A = - 3.037p ＋ 0. 0355 （p, mg/mL）, and the correlation coefficient is 0. 9995. The relative standard deviation of six determination is 0. 6%. The apparent molar absorptivity of the complex is 6. 19 ~ 104 L . mol-1 . cm-1 at 634 nm. Moreover, the absorption spectral characteristics of the erythromycin ethylsuccinate-methyl green complex, the affecting factors, the optimum conditions of the reaction, the effects of coexisting substances and their analytical application were primarily discussed. Based on these, we developed a new ethylsuccinate. The detection limit of this method applied to analysis of erythromycin ethylsuccinate fading spectrophotometric method is 0. 21μg/mL. The method has in its tablets. for detecting erythromycin good selectivity, it can be applied to analysis of erythromycin ethylsuccinate in its tablets.