Procedures are described for rapid lipase hydrolysis of triglycerides, isolation of the hydrolytic products by TLC and their conversion to methyl esters and fatty acid analysis by GLC. The techniques are applicable to a few mg of triglycerides or fats. Examples of data obtained with purified triglycerides i~dieate that the specific action of pancreatic lipase for the 1,3 ester groups is nearly absolute and the technique may be used as a criterion of purity of di-and tri-aeid triglycerides. Ca. 83% of the palmitie but only 10-12% of stearic and Cls unsaturated acids of commercial lard occur in 2-position.

A simple and convenient method for the quantitative preparation of methyl esters of fatty acids from glyceride fats and oils is described. The procedure, using potassium methylate as catalyst and a heating interval of 2 min at 65C in a closed vial, is applicable to fats containing both low and high molecular weight fatty acids such as butteroil. The methyl esters of samples ranging from a few mg to 30 mg are isolated by CS2 extraction and a TLC technique. A similar procedure using sulfuric acid in methanol as catalyst is described for the conversion of free fatty acids to methyl esters. For the routine analysis by GLC of fats and oils such as lard, tallow, soybean, cottonseed oil or butteroil, no isolation of the methyl ester is required. A CS2 extraction carried out in the reaction vial allows the GLC analysis immediately after the reaction period (2 min).

Rearrangement of 1-4 double bonds of diand polyolefinic compounds to the conjugated position has been shown to occur during treatment with catalysts such as nickel2'3 or alkali4'6 at high temperatures, and during autoxidation.6'7 Evidence for this change has been based to a considerable extent on spectroscopic data. Relatively little is known

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Summary Optimum conditions for production of maximum conjugation of methyl arachidonate were determined. These comprise heating the sample in 21% KOH glycol for 15 minutes at 180°C. The optimum conditions of isomerization have also been applied to methyl linoleate, methyl linolenate, methyl eicosapentaenoate, and docosapentaenoate prepared by physical methods. These conditions greatly increased the sensitivity of the spectrophotometric method for all the polyun‐saturated acids except linoleic, for which the sensitivity was unchanged. Analyses of a series of fats and oils isomerized under optimum conditions and also under standard conditions were in good agreement. Constants are given for use when pentaene acids are present as well as for acids of less unsaturation. Spectroscopic evidence strongly indicates than pentaene acids are present in lard.