根据吸光度比-光谱曲线，选定215.7 nm及264.1 nm作为测定氯唑沙宗(CRXZ)和对乙酰氨基酚(ACAP)的波长对.制备标准曲线时，首先配制由CRZX和ACAP基准物配制的标准溶液和由两者配成的混合标准系列，并在上述两波长处分别测得各试液的吸光度，再用文中提供的公式计算吸光度比值R和吸光度之差ΔR，最后建立ΔR对CRZX或ACAP浓度之间的线性回归方程.分析试样时，取复方氯唑沙宗片适量溶于溶剂中并定量稀释.分取部分试液按制备标准曲线的方法测得试液的吸光度并计算其比值R和ΔR.根据相应回归方程计算相应组分的含量.精密度及回收率试验所得结果的RSD(n=7)值为1.28%(CRXZ)及0.84%(ACAP),两者的平均回收率均为100.0%.

It was reported that from the absorbance-ratio spectral curve,the wavelength pair for the determination of chlorzoxazone (CRXZ) and p-acetaminophenol (ACAP) was chosen as 215.7 nm and 264.1 nm. The calibration curve was prepared by determining the absorbance of a set of mixed standard solutions of CRXZ and ACAP of appropriate concentrations at the wavelengths given above,then calculate the values of absorbance ratio R and ΔR according to the formula given in the paper,and finally the linear regression equations of ΔR against concentration of CRZX or of ACAP were established. In the analysis of chlorxazone compound tablets,a definite amount of the sample was taken and dissolved in the solvent and diluted to a definite volume with the same solvent. An aliquat of the solution was taken and treated in the same way as in the preparation of calibration curve. From the absorbance values obtained,calculate the values of ΔR and find the corresponding concentrations from the regression equations. In the test for precision and recovery of this method RSD′s (n=7) obtained for CRXZ was 1.28% and for ACAP was 0.84%,and average recoveries were 100.0% for both constituents.