Lee C M, Trevino B, Chaiyawat M
Department of Food Science and Nutrition, University of Rhode Island, West Kingston 02892, USA.
J AOAC Int. 1996 Mar-Apr;79(2):487-92.
Solvent systems that have been developed for lipid extraction include chloroform-methanol, n-hexane-isopropyl alcohol, and methylene chloride-methanol. The extraction methods are labor intensive, lack precision, or require a large volume of solvent. Correct computation of lipid content calls for full recovery of solvent after extraction, but recovery always is incomplete because of unaccounted solvent residue that remains in jar, filter paper, and homogenized tissue. A rapid and simple extraction method coupled with correct computation was developed for determining total lipids in fish tissue. The method uses chloroform-methanol and an Eberbach blending jar. Variables examined were chloroform-methanol ratio, solvent-to-sample ratio, and phase separation time. Precision was within 0.5%. Conventional computation of lipid content depends on the volume of chloroform measured after filtration. This volume does not include unaccounted solvent residue. Thus, a time-consuming second extraction is required for complete recovery. The mass balance of each extraction and filtration step confirmed that the correct volume of chloroform (measured plus unaccounted) was close to the theoretical volume. The procedure eliminates problems associated with laborious filtration and variation in chloroform volume readings and does not require an exact reading of chloroform volume. Instead it allows use of a theoretical volume, which depends on solvent volume and ratio used.
已开发出用于脂质提取的溶剂系统，包括氯仿 - 甲醇、正己烷 - 异丙醇和二氯甲烷 - 甲醇。这些提取方法劳动强度大、缺乏精确性或需要大量溶剂。脂质含量的正确计算要求在提取后完全回收溶剂，但由于留在罐子、滤纸和匀浆组织中的未计入的溶剂残留，回收总是不完全的。为测定鱼组织中的总脂质，开发了一种快速简单的提取方法并结合正确的计算方法。该方法使用氯仿 - 甲醇和一个埃伯巴赫混合罐。所研究的变量有氯仿 - 甲醇比例、溶剂与样品比例以及相分离时间。精密度在0.5%以内。脂质含量的传统计算取决于过滤后测得的氯仿体积。这个体积不包括未计入的溶剂残留。因此，为了完全回收需要进行耗时的二次提取。每个提取和过滤步骤的质量平衡证实，氯仿的正确体积（测得的加上未计入的）接近理论体积。该方法消除了与费力过滤以及氯仿体积读数变化相关的问题，并且不需要精确读取氯仿体积。相反，它允许使用理论体积，该理论体积取决于所用的溶剂体积和比例。
