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Rapid and simple method for determination of N ε ‐(carboxymethyl)lysine and N ε ‐(carboxyethyl)lysine in urine using gas chromatography[sol ]mass spectrometry
Author(s) -
Petrovič Robert,
Futas Ján,
Chandoga Ján,
Jakuš Vladimír
Publication year - 2005
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.491
Subject(s) - chemistry , chromatography , urine , lysine , mass spectrometry , isotope dilution , detection limit , gas chromatography , gas chromatography–mass spectrometry , acetonitrile , amino acid , biochemistry
A new procedure was developed to determine in urine the concentrations of N ε ‐(carboxymethyl)lysine (CML) and N ε ‐(carboxyethyl)lysine (CEL), the major products of oxidative modification of glycated proteins, to assess levels of oxidative stress in physiological systems. The urine samples were acetonitrile‐deproteinized, then derivatized by ethylchloroformate, and N(O,S)‐ethoxycarbonyl ethyl esters of amino acids were analysed by isotope dilution gas chromatography[sol ]mass spectrometry. Recovery averaged 89%. Linearity was excellent ( r = 0.998–0.999) in the 0.5–25 µmol[sol ]L range for CML and CEL. The limit of detection of this assay was 0.1 µmol[sol ]L (corresponding to 0.20 pmol of CML or CEL on column). Intra‐day and inter‐day precisions were likewise excellent, with relative standard deviations <4.63 and <6.15%, respectively. Accuracy of CML and CEL determination (15 µmol[sol ]L) was 2.9 and 5.9% of the estimated theoretical value. The time from obtaining the urine sample to determination of the concentration from the chromatographic peak was 80 min or less. This method is sensitive, reproducible, accurate, relatively cheap and very simple. It can be useful for laboratories involved in the diagnosis and monitoring of age‐related chronic diseases. Copyright © 2005 John Wiley & Sons, Ltd.