Determination of total lipid using non-chlorinated solvents

Abstract

The restrictions on the use of chlorinated solvents under the Montreal Protocol makes it necessary to develop an alternative method to the Bligh and Dyer lipid extraction as currently applied to marine tissues. Several different solvent mixtures were systematically tested as a replacement for chloroform. The presence of a polar solvent is a prerequisite in order to obtain phase separation between the aqueous and organic phases, but too high a concentration of solvent in the aqueous phase prevents the more polar lipids from being extracted. A high content of water in the organic phase can result in co-extraction of non-lipids. Several combinations of solvents may be able to extract lipids, but for reasons of safety and toxicity, a propan-2-ol–cyclohexane–water (8 + 10 + 11 v/v/v) mixture has been proposed. The method is not sensitive to a wide range of sample-phase volume ratios provided that the solvent compositions remain constant. Application to plaice, mussel and herring samples showed results that were in agreement with the extraction following Bligh and Dyer using chloroform and methanol.