title: Practical determination of methotrexate in serum of rheumatic patients by LC-MS/MS.
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.
authors.affiliation: Department of Pharmacy, Sasebo Chuo Hospital, 15 Yamatocho, Sasebo, Nagasaki, 857-1195, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Sonemoto
authors.forename: Narumi
authors.initials: N
authors.lastname: Kono
authors.forename: Rie
authors.initials: R
authors.lastname: Ikeda
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Wada
authors.forename: Yukitaka
authors.initials: Y
authors.lastname: Ueki
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Nakashima
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018501:Antirheumatic Agents / Q000097:blood* / Q000627:therapeutic use; D002853:Chromatography, Liquid / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000097:blood* / Q000627:therapeutic use; D008875:Middle Aged; D015203:Reproducibility of Results; D012216:Rheumatic Diseases / Q000097:blood* / Q000188:drug therapy; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D018501:Antirheumatic Agents; D008727:Methotrexate