title: An isotope dilution capillary electrophoresis/tandem mass spectrometry (CE-MS/MS) method for the simultaneous measurement of choline, betaine, and dimethylglycine concentrations in human plasma.
abstract: Plasma concentrations of choline, betaine, and dimethylglycine provide valuable information on the flow of methyl groups in key biological processes, particularly during folate deficiency states. We developed a new method to simultaneously measure these analytes in human plasma. Following sample deproteinization using acetonitrile, an aliquot was evaporated to dryness under vacuum to be then taken up by water. Finally, analytes were separated by capillary electrophoresis and detected by electrospray ionization triple-quadrupole mass spectrometry, in multiple reaction monitoring mode, using two stable isotope-labeled internal standards. Linearity of the calibration curves of each analyte was good (R(2) > 0.99). Average limits of detection (LODs) and limits of quantification (LOQs) for choline, betaine, and dimethylglycine were, respectively, 0.43, 0.62, and 0.31 μmol/L and 1.52, 2.11, and 0.97 μmol/L. Mean recovery of three replicates of two spiked concentrations levels was close to 100 % for all of the analytes. Repeatability and intermediate precision, expressed as %RSD of measurements, were <9 %. The method, applied to measure analytes in samples from 30 patients with chronic kidney disease and 30 age- and sex-matched healthy controls, was able to detect differences between groups and the sexes.
authors: Department of Biomedical Sciences, School of Medicine, University of Sassari, Viale San Pietro 43/B, 07100, Sassari, Italy.
authors: Mauro
authors: M
authors: Forteschi
authors: Department of Biomedical Sciences, School of Medicine, University of Sassari, Viale San Pietro 43/B, 07100, Sassari, Italy.
authors: Angelo
authors: A
authors: Zinellu
authors: Department of Biomedical Sciences, School of Medicine, University of Sassari, Viale San Pietro 43/B, 07100, Sassari, Italy.
authors: Stefano
authors: S
authors: Assaretti
authors: Department of Clinical Pharmacology, School of Medicine, Flinders University, Bedford Park, Adelaide, South Australia, 5042, Australia.
authors: Arduino A
authors: AA
authors: Mangoni
authors: Department of Biomedical Sciences, School of Medicine, University of Sassari, Viale San Pietro 43/B, 07100, Sassari, Italy.
authors: Gianfranco
authors: G
authors: Pintus
authors: Department of Biomedical Sciences, School of Medicine, University of Sassari, Viale San Pietro 43/B, 07100, Sassari, Italy.|Quality Control Unit, University Hospital Sassari (AOU), Viale San Pietro 43/B, 07100, Sassari, Italy.
authors: Ciriaco
authors: C
authors: Carru
authors: Department of Biomedical Sciences, School of Medicine, University of Sassari, Viale San Pietro 43/B, 07100, Sassari, Italy. ssotgia@uniss.it.
authors: Salvatore
authors: S
authors: Sotgia
mesh_terms: D000368:Aged; D001622:Betaine / Q000097:blood*; D002794:Choline / Q000097:blood*; D019075:Electrophoresis, Capillary / Q000379:methods*; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling / Q000379:methods; D057230:Limit of Detection; D008297:Male; D008875:Middle Aged; D012521:Sarcosine / Q000031:analogs & derivatives* / Q000097:blood; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D001622:Betaine; C025138:dimethylglycine; D002794:Choline; D012521:Sarcosine
keywords: Betaine-homocysteine methyltransferase; Capillary electrophoresis; One-carbon metabolism; Quaternary ammonium cations; Tandem mass spectrometry