title: On-line high speed lipid extraction for nanoflow liquid chromatography-tandem mass spectrometry.
abstract: An on-line lipid extraction method is introduced by utilizing a short capillary extraction column using HILIC and C4 particles prior to nanoflow liquid chromatography-tandem mass spectrometry (nLC-MS/MS). The on-line extraction using a urine sample spiked with PL standards showed similar or slightly higher recovery values (86%-96%) of phospholipids (PLs) compared to those obtained by the conventional off-line extraction based on the Folch method with or without using the air-exposed drying process. In this study, we demonstrated that PL oxidation can occur during the air-exposed drying process of lipid extracts in standard liquid-liquid extraction procedures, which was confirmed by the oxidized PL (OxPL) molecules that were generated from an off-line extraction using a few PL standards. Quantitative comparison of these OxPL species between on- and off-line extraction followed by nLC-MS/MS with multiple reaction monitoring (MRM) analysis showed a significant decrease (2-10 fold) in unwanted OxPL species when on-line extraction was employed. While the number of identified PLs from a urine sample was somewhat lower than those by off-line extraction, the number of OxPLs was significantly reduced (from 70 to 22) with on-line extraction. The new method offers high speed (∼5min) automated extraction of PLs with nLC-MS/MS analysis and presents the possibility of handling a biological sample with a very limited amount of lipids.
authors.affiliation: Department of Chemistry, Yonsei University, Seoul, 120-749, South Korea.
authors.forename: Ju Yong
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Yonsei University, Seoul, 120-749, South Korea.
authors.forename: Joon Seon
authors.initials: JS
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Yonsei University, Seoul, 120-749, South Korea.
authors.forename: Se Mi
authors.initials: SM
authors.lastname: Park
authors.affiliation: Department of Chemistry, Yonsei University, Seoul, 120-749, South Korea.
authors.forename: Seul Kee
authors.initials: SK
authors.lastname: Byeon
authors.affiliation: Department of Chemistry, Yonsei University, Seoul, 120-749, South Korea. Electronic address: mhmoon@hotmail.com.
authors.forename: Myeong Hee
authors.initials: MH
authors.lastname: Moon
mesh_terms: D001331:Automation / Q000295:instrumentation / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D059625:Liquid-Liquid Extraction / Q000295:instrumentation / Q000379:methods*; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000737:chemistry / Q000302:isolation & purification* / Q000652:urine; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D010743:Phospholipids
keywords: LC-ESI–MS/MS; On-line lipid extraction; Oxidation of lipids; Phospholipids; Urinary lipids