title: Quantitative determination of lysophosphatidic acid by LC/ESI/MS/MS employing a reversed phase HPLC column.
abstract: Lysophosphatidic acid (LPA) is a class of lipids that play multiple biological functions. Several reports show that they are potential biomarkers for diagnosing ovarian cancer. Therefore, it is necessary to accurately quantify their levels in biological samples. Here we report a high throughput LC/ESI/MS/MS (liquid chromatography electrospray tandem mass spectrometry) method employing a reversed phase C18 column to quantify LPA. In this method, a [(13)C(16)] labeled 16:0 LPA is used as the internal standard and the lipids are extracted out from biological samples using Bligh-Dyer method under highly acidic condition. The total run time is 8min. The detection limits of the assay reach fmol level and the CV% of the assay are within 10%. Using this method, we quantify the levels of six LPA species (16:0, 18:2, 18:1, 18:0, 20:4, and 22:6 LPA) in plasma samples. We find that some unknown compounds present in plasma can interfere with the quantification of LPA if they are not well separated from LPA. These unknown compounds are more hydrophobic than LPA and can be removed by thin-layer chromatography (TLC). We also find that the levels of LPA species in human plasma generally follow the order: 18:2 LPA>16:0 LPA, 20:4 LPA>18:1 LPA, 22:6 LPA, and 18:0 LPA.
authors.affiliation: Frantz BioMarkers LLC, 7740 Metric Drive, Mentor, OH 44060, USA. lshan@frantzbiomarkers.com <lshan@frantzbiomarkers.com>
authors.forename: Lian
authors.initials: L
authors.lastname: Shan
authors.forename: Keeve
authors.initials: K
authors.lastname: Jaffe
authors.forename: Shanping
authors.initials: S
authors.lastname: Li
authors.forename: Lorelei
authors.initials: L
authors.lastname: Davis
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D002853:Chromatography, Liquid / Q000379:methods*; D002855:Chromatography, Thin Layer; D005260:Female; D006801:Humans; D008246:Lysophospholipids / Q000097:blood*; D010051:Ovarian Neoplasms / Q000097:blood*; D011786:Quality Control; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D008246:Lysophospholipids; C032881:lysophosphatidic acid