目的　测定虎杖及其制剂中大黄素及大黄素甲醚的含量。方法　样品经甲醇回流提取 ,用硅胶G薄层板 ,以氯仿 -甲醇 -苯 (2 0∶1 5∶0 5 )为展开剂 ,4 5 0nm和 4 4 3nm为测定波长 ,单波长线性扫描 ,外标法定量。结果　本方法的回收率为 99 2 3%和 98 6 3% ,所含杂质对测定无干扰 ,在规定的浓度范围内呈良好线性关系 ,测定结果的RSD分别为 1 6 7%和 1 5 3% (n =5 )。结论　本法操作简便 ,快速准确 ,重现性好 Objective To determine the content of emodin and emodin in Polygonum cuspidatum and its preparations. Methods Samples were extracted by refluxing with methanol, silica gel G thin-layer plates, chloroform-methanol-benzene (2:0:15∶0 5 ) as developing solvent, 450nm and 4 4 3nm as measuring wavelength, single wavelength linear scanning, External standard method. Results The recoveries of the method were 99 2 3% and 98 6 3%. The impurities contained had no interference to the determination. The linearity was well within the specified concentration range. The RSD of the determination results were 16 7% and 1 5 3 , respectively. % (n =5). Conclusion This method is simple, rapid, accurate and reproducible