High-performance liquid chromatographic separations of soy phospholipids

High-performance liquid chromatography methods to quantitate soy phospholipids vary as to which phospholipids are analyzed, degree of method ruggedness, precision, time, and standards. Fluid and deoiled soy lecithins were analyzed by three different high-performance liquid chromatography methods, including the American Oil Chemists' Society (AOCS) Method la 7b-91. The other methods include an isocratic mixed phase (normal-phase column and reverse-phase solvent) method with ultraviolet detection, and a binary gradient normal-phase (proposed International Lecithin and Phospholipid Society) method with light-scattering detection. A set of 20 analyses were repeated on three different days for fluid and deoiled product by the three methods. The statistical comparison involved the selected methods and the phosphatidylcholine and phosphatidylethanolamine measured data, which were the common analytes among the methods. The precision for the mixed phase method and the Proposed International Lecithin and Phospholipid Society method was better than that for the AOCS method. Selection of reference standards was an important issue in defining the results. Column conditioning varied by 2-3 h for the Proposed International Lecithin and Phospholipid Society method, 16 h for the mixed phase method, and 2-3 d for the AOCS method. The ruggedness for the methods showed the following descending order: proposed International Lecithin and Phospholipid Society, mixed phase, AOCS.