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Practical determination of methotrexate in serum of rheumatic patients by LC‐MS/MS
Author(s) -
Sonemoto Emi,
Kono Narumi,
Ikeda Rie,
Wada Mitsuhiro,
Ueki Yukitaka,
Nakashima Kenichiro
Publication year - 2012
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.2700
Subject(s) - chemistry , chromatography , methotrexate , calibration curve , detection limit , mass spectrometry , liquid chromatography–mass spectrometry , acetic acid , methanol , tandem mass spectrometry , acetonitrile , matrix (chemical analysis) , biochemistry , organic chemistry , immunology , biology
ABSTRACT A rapid and simple liquid chromatography tandem mass spectrometry method for determination of methotrexate (MTX) in rheumatic patients' serum is described. Serum spiked with pterin as an internal standard was deproteinized with methanol. The separation of MTX from interfering peaks in matrix was achieved on a Luna 3 µm C 18 (100 × 4.6 mm i.d.) column with a mixture of 1% acetic acid and acetonitrile (88:12, v/v) within 5 min. Multiple reaction monitoring transitions monitored for MTX were m / z 455.2–308.1. The calibration curve of MTX in serum showed a good linearity ( r = 0.999). Limits of detection and quantification of MTX at a signal‐to‐noise ratio of 3 and 10 were 3.0 n m (4.4 fmol/injection) and 10.0 n m (14.5 fmol/injection), respectively. The accuracy and precision for intra‐ and inter‐day assays were 94.6–106.5% and <5.5 and <5.1%, respectively. Furthermore, the proposed method was successfully applied to the sera nine rheumatic patients receiving MTX treatment. Copyright © 2012 John Wiley & Sons, Ltd.