Optimized separation of nonpolar and polar lipid classes from wheat flour by solid‐phase extraction

A method combining solid‐phase extraction on prepacked silica and aminopropyl bonded‐phase (Bond‐Elut) columns has been developed for the separation of neutral lipids, glycolipids and phospholipids from wheat flour into individual classes in high yield and homogeneity. Chromatography on a single silica column (500 mg) with solvent combinations of increasing polarity resulted in complete separation of steryl esters, triglycerides, free fatty acids, 1,2‐diglycerides, 1,3‐diglycerides, monoglycerides, monogalactosylglycerides, digalactosylglycerides, phosphatidylcholine and lysophosphatidylcholine. Chromatography on an aminopropyl bonded‐phase column (500 mg) with ternary mixtures of chloroform/methanol/ammonium hydroxide led to the proper separation of N‐acyl‐phosphatidylethanolamine and N‐acyl‐lysophosphatidylethanolamine, previously coeluted on the prepacked silica column. Cross contamination among phospholipid classes tested by normal‐phase high‐performance liquid chromatography was always less than 14%.