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.

Recent advances in capillary electrophoresis‐mass spectrometry: Instrumentation, methodology and applications

“…Biomarker identification is performed in different biological fluids, blood being one of the most promising amongst them. In recent studies, metabolites and especially amino acids were identified as biomarkers in blood for amyotrophic lateral sclerosis , chronic kidney disease (CKD) , major depressive disorder , onchocercias infection , osteoporosis , Parkinson's disease , pancreatic cancer , urinary tract symptoms and metabolic syndrome in postmenopausal women by CZE‐MS. For identification and accurate quantification of biomarkers for inborn errors of metabolism from dried blood spots, DiBattista et al.…”

Advances in the Determination of Nonprotein Amino Acids in Foods and Biological Samples by Capillary Electrophoresis

“…By using this methodology, it was possible to carry out the quantification of pyroglutamic acid in case of paracetamol overdose. Finally, Forteschi et al, designed an isotope dilution CE-MS 2 method to detect, for the first time, betaine, choline and dimethylglycine simultaneously in plasma samples, since they provide relevant information related to the flow of methyl groups in key biological processes, particularly in folate deficiency stages [40]. Under the experimental conditions detailed in Table 2, the compounds were detected in 22 min achieving LODs of 0.43, 0.62, and 0.31 M for choline, betaine and dimethylglycine, respectively.…”

Recent advances in amino acid analysis by capillary electromigration methods: June 2015–May 2017

“…Average LODs for choline, betaine, and dimethylglycine were 0.43, 0.62, and 0.31 μmol/L. The method was applied to plasma of 30 patients with chronic kidney disease .…”