Quantitative Determination of Total Lipids

The amoimts of total lipids extracted from plasma or tissues are best determined by gravimetric or photometric procedures. These methods are superior to older procedures, e.g. bichromate oxidation according to Bloor (1928), because they do not alter the material and permit further procedures to be performed or are less time consuming. 

For gravimetry aliquots of purified extracts are evaporated and the residues dried and weighed. A detailed description of this technique was given by Sperry (1955). 

A photometric procedure which is based on the reaction of unsaturated fatty acids with concentrated sulfuric acid and a mixture of phosphoric acid and vanil-line with development of a pink color was introduced by Zollner and Kirsch (1962). Since in this reaction the various lipids show different extinction coefficients calibration is necessary according to gravimetric values. This method is also applicable directly to plasma samples without previous extraction. 

Turbidity occurring after the addition of diluted sulfuric acid to lipid dioxane extracts permits measurement of total lipids from very small amounts of serum (Searcy et al. 1963). 

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Sohn, J. H., Y. S. Taki, H. Ushio, and T. Ohshima. 2005. Quantitative determination of total lipid hydroperoxides by a flow injection analysis system. Lipids 40 203-209. Stepanyan, V., A. Arnous, C. Petrakis, P. Kefalas, and A. Calokerinos. 2005. 

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