Sorenson Wendy R, Sullivan Darryl
Covance Laboratories, 3301 Kinsman Blvd, Madison, WI 53704, USA.
J AOAC Int. 2007 May-Jun;90(3):670-8.
An interlaboratory study was conducted to evaluate a method for the determination of campesterol, stigmasterol, and beta-sitosterol in saw palmetto raw materials and dietary supplements at levels >1.00 mg/100 g based on a 2-3 g sample. Test samples were saponified at high temperature with ethanolic KOH solution. The unsaponifiable fraction containing phytosterols (campesterol, stigmasterol, and beta-sitosterol) was extracted with toluene. Phytosterols were derivatized to trimethylsilyl ethers and then quantified by gas chromatography with hydrogen flame ionization detection. Twelve blind duplicates, one of which was fortified, were successfully analyzed by 10 collaborators. Recoveries were obtained for the sample that was fortified. The results were 99.8, 111, and 111% for campesterol, stigmasterol, and beta-sitosterol, respectively. For repeatability, the relative standard deviation (RSDr) ranged from 3.93 to 17.3% for campesterol, 3.56 to 22.7% for stigmasterol, and 3.70 to 43.9% for beta-sitosterol. For reproducibility, the RSDR ranged from 7.97 to 22.6%, 0 to 26.7%, and 5.27 to 43.9% for campesterol, stigmasterol, and beta-sitosterol, respectively. Overall, the Study Director approved 5 materials with acceptable HorRat values for campesterol, stigmasterol, and beta-sitosterol ranging from 1.02 to 2.16.
开展了一项实验室间研究，以评估一种基于2 - 3克样品测定锯叶棕原材料和膳食补充剂中菜油甾醇、豆甾醇和β-谷甾醇含量的方法，含量要求高于1.00毫克/100克。测试样品用乙醇氢氧化钾溶液在高温下皂化。含有植物甾醇（菜油甾醇、豆甾醇和β-谷甾醇）的不皂化物用甲苯萃取。植物甾醇衍生化为三甲基硅醚，然后通过带有氢火焰离子化检测的气相色谱法定量。10位协作人员成功分析了12个盲样复制品，其中一个进行了加标。对加标样品获得了回收率。菜油甾醇、豆甾醇和β-谷甾醇的回收率分别为99.8%、111%和111%。对于重复性，菜油甾醇的相对标准偏差（RSDr）范围为3.93%至17.3%，豆甾醇为3.56%至22.7%，β-谷甾醇为3.70%至43.9%。对于再现性，菜油甾醇、豆甾醇和β-谷甾醇的RSDR分别为7.97%至22.6%、0至26.7%和5.27%至43.9%。总体而言，研究主任批准了5种材料，其菜油甾醇、豆甾醇和β-谷甾醇的HorRat值在1.02至2.16之间，可接受。
