Densitometric quantification of individual phospholipids. Improvement and evaluation of a method using molybdenum...

A densitometric method for simultaneous quantification of individual phospholipids based on visualization with molybdenum blue reagent is presented. Previously reported problems concerning colour instability have been solved. The method is specific for phosphorus-containing compounds and independent of the degree of fatty acid unsaturation. The molar absorptivities of most analysed phospholipids do not differ more than 10% from that for phosphatidylcholine from egg yolk. For cases of greater deviation (sphingomyelin, lysophosphatidylcholine and phosphatidylserine), analysis is accomplished by use of appropriate standard mixtures. The between-series coefficient of variation is ca. 9%. The method is compared to a preparative thin-layer chromatographic assay and another commonly used densitometric method.