title: Determination of flomoxef in human plasma by liquid chromatography/electrospray ionization tandem mass spectrometry.
abstract: A specific, sensitive, rapid and reproducible method for the determination of flomoxef in human plasma using high-performance liquid chromatography-tandem mass spectrometry was developed and validated. Flomoxef was detected using an electrospay ionization method operated in negative-ion mode. Chromatographic separation was performed in gradient elution mode on a Luna® C18(2) column (3 μM, 20 × 4.0 mm) at a flow rate of 1 mL/min and runtime 3.5 min. The mobile phase consisted of acetonitrile and water containing 0.1% formic acid as additive. Extraction of flomoxef from plasma and precipitation of plasma proteins was performed with acetonitrile with an absolute recovery of 86.4 ± 1.6%. The calibration curve was linear with a correlation coefficient of 0.999 over the concentration range 10-5000 ng/mL and the lower limit of quantification was 10 ng/mL. The intra- and inter-day precisions were <11.8%, while the accuracy ranged from 99.6 to 109.0%. A stability study of flomoxef revealed that it could be successfully analyzed at 4 ºС over 24 h, but it was unstable in solutions at room temperature during short-term storage (4 h) and several freeze-thaw cycles.
authors.affiliation: Bioscreening Laboratory Co. Ltd, 20 Geroev Panfilovtzev Str. Bldg 1, Moscow, 125480, Russia.
authors.forename: Oxana Yu
authors.initials: OY
authors.lastname: Kravtsova
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Paramonov
authors.forename: Natalya I
authors.initials: NI
authors.lastname: Vasilevich
authors.forename: Denis N
authors.initials: DN
authors.lastname: Kazyulkin
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Vlasova
authors.forename: Michael
authors.initials: M
authors.lastname: Engsig
mesh_terms: D002511:Cephalosporins / Q000097:blood* / Q000737:chemistry; D002853:Chromatography, Liquid; D004355:Drug Stability; D006801:Humans; D016018:Least-Squares Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D002511:Cephalosporins; C045693:flomoxef
keywords: LC-MS/MS analysis; flomoxef; human plasma; tandem mass-spectrometry