John Owen - An improved assay for platelet-activating factor using HPLC-tandem mass spectrometry.

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      Publication Details (including relevant citation   information):

      J Lipid Res 46:373-382

      Abstract:

      We describe an improved assay for platelet-activating factor   (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) using   HPLC-tandem mass spectrometry (LC-MS/MS). The present method can   readily detect as little as 1 pg (1.9 fmol) of PAF, a significant   improvement over previously described LC-MS/MS methods, and gives   a linear response up to 1,000 pg of PAF. Our method also   overcomes the artifacts from isobaric lipids that have limited   the usefulness of certain existing LC-MS/MS assays for PAF. In   the course of these studies, we detected three novel lipid   species in human neutrophils. One of the novel lipids appears to   be a new molecular species of PAF, and the other two have   chromatographic and mass spectrometric properties consistent with   stearoyl-formyl-glycerophosphocholine and   oleoyl-formyl-glycerophosphocholine. These observations identify   previously unknown potential interferences in the measurement of   PAF by LC-MS/MS. Moreover, our data suggest that the previously   described palmitoyl-formyl-glycerophosphocholine is not unique   but rather is a member of a new and poorly understood family of   formylated lipids.

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