目的 利用化合物在高效液相色谱的保留时间测定强脂溶性化合物淫羊藿次苷-Ⅱ与苷元的油水分配系数。方法 选取一系列结构相似的化合物作为参考物质，采用摇瓶法或通过数据库获得其油水分配系数(partition coefficient)的对数lgP。利用高效液相色谱法测定参考物质在不同浓度有机相条件下的保留时间，外推得到有机相浓度为零时的容量因子k_w，建立参考物质lgk_w与lgP的线性关系方程式。用同样方法得到检验物质槲皮素和芒柄花素以及待测物质淫羊藿次苷-Ⅱ和苷元的k_w。利用参考物质的线性关系方程式计算得到上述4个化合物的lgP，并和采用摇瓶法测定的检验物质的lgP作比较。结果 建立了lgk_w与lgP的关系方程式：lgP=(1.532±0.091)lgk_w-(1.805±0.301) (r²=0.959 0)，摇瓶法测定检验物质的lgP在高效液相色谱法测定的lgP范围内， 说明所选一系列化合物在高效液相系统和正辛醇-水系统的分配行为相似，可以利用其在高效液相色谱上的保留时间来测定其在正辛醇-水系统中的分配系数。计算淫羊藿次苷-Ⅱ与苷元的lgP分别为（5.114±0.712）和（6.074±0.769）。结论 HPLC可较准确、方便、快速的测定强脂溶性化合物（lgP>4）油水分配系数。

OBJECTIVE The aim of the study is to measure partition coefficients of two highly hydrophobic compounds， icariside-Ⅱ and icaritin， based on their retention time on HPLC. METHODS A series of compounds with similar structure were selected as the reference substances and their partition coefficients were determined by shake-flask method or obtained from the science finder database. The retention time of the above reference substances was determined under different concentrations of organic phase. Logk_w was obtained by extrapolating to zero concentration of organic phase. A linear relationship between lgP and lgk_w was established. Logk_w of two substances for validation purpose (quercetin and formononetin) and two substances to be measured (icariside-Ⅱ and icaritin) were obtained by the same method. LogP of above four compounds was calculated from the linear regression equation obtained from the reference substances and compared with the lgP of validation substances determined by shake-flask method. RESULTS A linear regression equation between lgP and lgk_w was established： lgP=(1.532±0.091)lgk_w-(1.805±0.301)， r²=0.959 0. The lgP of validation substances determined by shake-flask method is within the range of lgP measured by HPLC method， indicating that the partition of the selected compounds in HPLC system is similar to that in octanol-water system. Therefore， the partition coefficient could be determined using their retention time on HPLC. The calculated lgP value of icariside-Ⅱ and icaritin is （5.114±0.712） and （6.074±0.769）， respectively. CONCLUSION HPLC is an accurate， convenient and rapid method to determine the partition coefficient of highly hydrophobic compounds (lgP>4).