title: Differentiation and quantification of synthetic phosphatidylethanol (PEth) homologues by ¹H- and ¹³C-NMR in polar organic solvents.
abstract: Various phosphatidylethanol (PEth) derivatives, the corresponding reversed positional isomers (RPI-PEths), lyso-PEth-16:0, and penta-deuterium-labeled PEth analogs (d5-PEths), were synthesized by enzyme-independent synthetic routes. A general solvent system consisting of a mixture of acetone-d6 and methanol-d4 (97:3; v/v) was found to provide a good solubilizing capacity and excellent hydrogen-1 NMR ((1)H-NMR) peak resolution of various PEth homologues. Analytical differentiation of PEth from the corresponding RPI-PEth by carbon-13 NMR ((13)C-NMR) was demonstrated by comparison of the (13)C-NMR signals of the carbonyl groups, the allylic positions, and of the β-carbons. An exemplary stable long-term room temperature, DMSO-d6-based, and proton-sensitive quantitative nuclear magnetic resonance ((1)H-qNMR) independently quantified calibrator comprising PEth-16:0/18:1 for liquid chromatography (tandem) mass spectrometry (LC-MS/MS) analytical applications were prepared by employment of sodium dodecyl sulfate (SDS) as a solubilizing additive. In summary, novel hypothetically occurring PEth derivatives, e.g., RPI-PEths, have been independently synthesized with regio- and stereochemical control. Use of polar organic solvents, e.g., mixtures of acetone-d6 and methanol-d4 or DMSO-d6, improves spectral line shapes as compared to traditional hydrophobic solvents and allow for analytical differentiation between closely related PEth derivatives, as well as LC-MS/MS-independent concentration determination of dissolved single species by employment of (1)H-qNMR.
authors.affiliation: Department of Clinical Sciences, Division of Biomedical Engineering, Lund University, Skåne University Hospital, 221 85, Lund, Sweden, david.wensbo_posaric@med.lu.se.
authors.forename: David
authors.initials: D
authors.lastname: Wensbo Posaric
authors.forename: Anders
authors.initials: A
authors.lastname: Andersson
authors.forename: Karl-Erik
authors.initials: KE
authors.lastname: Bergquist
authors.forename: Anders
authors.initials: A
authors.lastname: Isaksson
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D020404:Glycerophospholipids / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012997:Solvents / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013237:Stereoisomerism
chemical_list: D020404:Glycerophospholipids; D012997:Solvents; C051521:phosphatidylethanol