A convenient method was developed for preparation of FAME in small amounts from glycerolipids of blood or breast milk. Initially, 0.04-0.06 mL blood or breast milk was spotted onto a small piece of filter paper (1.5 x 1.5 cm) that had been washed with acetone containing 0.05% 2,6-di-tert-butyl-p-cresol (BHT). Each piece, once it had dried, was put in a small test tube, to which 2 mL hexane and 0.2 mL 2 M KOH/methanol were added. After vigorous mixing or sonication for 2 min at room temperature, the solution was neutralized or acidified by the addition of a few drops of acetic acid. To the solution was added 2 mL H2O, and then the hexane layer that separated was concentrated to dryness in vacuo. The FAME obtained were analyzed by GC. The method was applicable to the analysis of a large number of blood and breast milk samples, and the arachidonate/(eicosapentaenoate + docosahexaenoate) ratios could be determined rapidly.
Catalytic properties of metal phosphates were investigated for gas-phase dehydration of 1,2-propanediol to propanal in the presence and absence of steam in the temperature range of 150–340 °C. Boron, aluminum, and nickel phosphates showed promising catalytic activity for the dehydration reaction. Especially, boron phosphate showed outstanding catalytic activity at a low reaction temperature and high selectivity to propanal without formation of competitive dehydration products such as acetone and allyl alcohol. The catalytic activity of boron phosphate was remarkably enhanced in the presence of steam cofed with 1,2-propanediol. The additional steam was also favorable for promoting hydrolysis of dioxolane, which is a byproduct formed through acetalization of propanal, resulting in the high yield of propanal over 95%. Boron phosphate showed more durable catalytic activity and much higher yield of propanal than conventional solid acid catalysts such as ZSM-5, silica–alumina and niobium oxide that have been reported to be active for the dehydration of 1,2-propanediol.
KOH in aqueous methanol catalyzes selective methanolysis of polar glycerolipids with O-ester-linked acyl residues, while triacylglycerols and sterol esters are inert in the solution. Based on these findings, a convenient and reliable method was developed for the preparation of fatty acid methyl esters (FAMEs) from polar glycerolipids in lipid mixtures without prior isolation. Methanolysis of polar glycerolipids was completed within 2.5 min by vortexing or 20 min by shaking with 0.7 M KOH/70% (v/v) methanol in the presence of hexane at 30 degrees C. The yields of FAMEs obtained by the present method were greater than 95%. The method was applied successfully to gas chromatographic analysis of the fatty acid compositions of polar glycerolipids in seed oil and blood. No obvious differences were found between the fatty acid compositions determined by the present method and those determined by conventional methods, including lipid extraction with chloroform/methanol followed by isolation of polar lipids by chromatography. The fatty acid composition of polar glycerolipids, including phospholipids, can be determined readily in many crude samples.
Sir:Glycerolipids, including TAG and phospholipids, are easily converted into FAME by alkali-catalyzed methanolysis for GC analysis of the FA compositions. Although CH 3 ONa is most commonly used as an alkali, NaOH-or KOH-catalyzed methanolysis is very convenient and useful (1,2). The procedure is not only simple and rapid but also safe. In contrast, the preparation of FAME from sterol esters is more difficult than that for glycerolipids. For example, FAME can be prepared from many samples of small amounts of blood or breast milk by KOH-catalyzed methanolysis on small pieces of filter paper
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