Separation of Pharmaceuticals by Capillary Electrophoresis using Partial Filling and Multiple-injections

• Main Author: Lodén, Henrik
• Format: Doctoral Thesis
• Language: English
• Published: Uppsala universitet, Avdelningen för analytisk farmaceutisk kemi 2008
• Subjects: Capillary Coating; Chiral Separation; Enantiomers; Mass-spectrometric Detection; Method Validation; Multiple-injection Capillary Zone Electrophoresis; Non-aqueous Capillary Electrophoresis; Organic Solvents; Pharmaceutical Analysis; Quantitative Analysis
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8841; http://nbn-resolving.de/urn:isbn:978-91-554-7211-5

Different multiple-injection methodologies and the partial filling technique (PFT) have been utilized for separation of pharmaceuticals by capillary elec-trophoresis. In multiple-injection capillary zone electrophoresis (MICZE), the samples and all standards, used for construction of the calibration curve, are analyzed within a single run. Four different modes of MICZE have been described by means of equations, which were experimentally verified. The developed equations facilitate the transfer from conventional single-injection CZE to one or more of these MICZE-modes, depending on the selectivity between the analyte and the injection marker. The applicability of two of these modes was then demonstrated by quantification of buserelin and salbutamol, re-spectively in commercially available pharmaceutical products. The content of buserelin in an injection solution was determined to 0.94 mg/ml, which only deviated slightly from the declared concentration (1 mg/ml). An alter-native mode of MICZE, offering a higher number of sequential sample injec-tions, was then utilized for single-run determination of salbutamol in 15 tab-lets, with a labelled content of 8 mg. The average content of the tablets was determined to 7.8 mg, with an intra-tablet variation of 3 % or less. Moreover, UV- and mass-spectrometric detection of enantiomeric amines, resolved by non-aqueous capillary electrophoresis (NACE), was demon-strated. Separation of enantiomeric amines was achieved using the chiral selector (-)-2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid, (-)-DIKGA. Introduction of the non-volatile (-)-DIKGA into the mass-spectrometer was avoided by using the PFT, where the capillary is only partially filled with electrolyte containing the chiral selector.