Stop-flow comprehensive two-dimensional liquid chromatography combined with mass spectrometric detection for phospholipid analysis

A novel comprehensive two-dimensional liquid chromatographic (LC x LC) system for characterization of phospholipid (PL) molecular species belonging to six phospholipid classes was developed. To tackle such a task, a silica hydrophilic interaction liquid chromatography (HILIC) column was used as the first dimension (D-1), and reversed-phase liquid chromatography (RP-LC) with a C18 column was used as the second dimension (D-2) in combination with mass spectrometric detection. Fraction transfer from the D-1 to the D-2 was performed by means of a two-position ten-port switching valve, operated under stop-flow conditions. The capability of the investigated LC x LC approach was demonstrated in the separation of phospholipid molecular species contained in two Folch-extracted cow's milk and plasma samples. Within the phosphatidylcholine class, up to 16 and 14 different species were identified, respectively, by means of the HILIC x RP-LC-MS system employed under both positive and negative ionization mode. (c) 2012 Elsevier B.V. All rights reserved.