title: Quantitative analysis of clindamycin in human plasma by liquid chromatography/electrospray ionisation tandem mass spectrometry using d1-N-ethylclindamycin as internal standard.
abstract: A new method for the quantitative analysis of clindamycin in human plasma by liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) is presented. Recently published methods possess a disadvantage because of their use of internal standards with extraction and ionisation properties different from those of clindamycin. To avoid these problems, d(1)-N-ethylclindamycin was synthesised for use as internal standard by N-demethylation and subsequent d(1)-N-ethylation. Plasma sample preparation was done by an easy and rapid liquid-liquid extraction using ethyl acetate. The method was validated in the expected concentration range for a pharmacokinetic study. Calibration graphs were linear within the range 0.05-3.2 microg/mL plasma. Intra-day precision was between 0.90% (2.8 microg/mL) and 3.25% (0.05 microg/mL), inter-day variability was found to be between 1.33% (0.7 microg/mL) and 2.60% (0.05 microg/mL). Inter-day accuracy showed deviations between 0.4% (0.05 microg/mL) and -4.8% (0.2 microg/mL). The method is simple and robust, and has been applied to the batch analysis of clindamycin during a pharmacokinetic study.
authors.affiliation: University Children's Hospital, Division of Analytical Biochemistry and Mass Spectrometry, Auenbruggerplatz 30, 8036 Graz, Austria.
authors.forename: Gerald N
authors.initials: GN
authors.lastname: Rechberger
authors.forename: Günter
authors.initials: G
authors.lastname: Fauler
authors.forename: Werner
authors.initials: W
authors.lastname: Windischhofer
authors.forename: Harald
authors.initials: H
authors.lastname: Köfeler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Erwa
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Leis
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D002981:Clindamycin / Q000031:analogs & derivatives / Q000097:blood* / Q000737:chemistry; D006801:Humans; D015394:Molecular Structure; D012015:Reference Standards; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: C473901:d1-N-ethylclindamycin; D002981:Clindamycin