title: Simultaneous quantification of etoposide and etoposide phosphate in human plasma by capillary electrophoresis using laser-induced native fluorescence detection.
abstract: A method using capillary electrophoresis with UV laser-induced native fluorescence detection was developed as a sensitive and selective assay for the simultaneous determination of etoposide and etoposide phosphate in human plasma. Laser-induced native fluorescence detection with a frequency-doubled argon ion laser at an excitation wavelength of 257 nm was used for the simultaneous assay of etoposide and etoposide phosphate in plasma to improve the sensitivity compared to that obtained with UV absorption. The detection system consists of an imaging spectrograph and an intensified CCD camera which views an illuminated 1.5-mm section of the capillary. This setup is able to record the whole emission spectra of the analytes to achieve additional wavelength-resolved electropherograms. In the concentration range of 200 microg/L-50 mg/L in plasma for etoposide and 100 microg/L-20 mg/L for etoposide phosphate, coefficients of correlation were better than 0.998. Within-day variation determined with three different concentrations showed accuracies ranging from 91.0 to 109.3% for etoposide and from 91.2 to 109.9% for etoposide phosphate (n = 6) with a precision of about 8%. Day-to-day variation presented accuracies ranging from 91.8 to 107.9% for etoposide and from 94.4 to 109.3% for etoposide phosphate with a relative standard deviation less than 6% (n = 5). To our knowledge, this is the first method for the simultaneous quantification of etoposide and etoposide phosphate in plasma samples.
authors.affiliation: Institute of Pharmaceutical Chemistry, University of Münster, Germany.
authors.forename: U B
authors.initials: UB
authors.lastname: Soetebeer
authors.forename: M O
authors.initials: MO
authors.lastname: Schierenberg
authors.forename: H
authors.initials: H
authors.lastname: Schulz
authors.forename: G
authors.initials: G
authors.lastname: Hempel
authors.forename: P
authors.initials: P
authors.lastname: Andresen
authors.forename: G
authors.initials: G
authors.lastname: Blaschke
mesh_terms: D000970:Antineoplastic Agents / Q000097:blood*; D019075:Electrophoresis, Capillary / Q000379:methods*; D005047:Etoposide / Q000031:analogs & derivatives / Q000097:blood*; D006801:Humans; D007834:Lasers; D008297:Male; D009943:Organophosphorus Compounds / Q000097:blood*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000970:Antineoplastic Agents; D009943:Organophosphorus Compounds; C061400:etoposide phosphate; D005047:Etoposide