Development of a gas chromatography–mass spectrometry method for the analysis of aminoglycoside antibiotics using experimental design for the optimisation of the derivatisation reactions

Abstract

A packed column GC–electron-capture detection method for the analysis of the aminoglycoside antibiotics kanamycin and gentamicin was adapted to capillary GC–MS. The analytes were derivatised using a two-step procedure involving trimethylsilylation of the hydroxyl groups with trimethylsilylimidazole and acylation of the amino groups with heptafluoro-butyrylimidazole. Electron impact mass spectra of the resulting derivatives of kanamycin A and gentamicins C 1, C 1a and C 2 are given and interpreted. The derivatisation procedure was optimised using experimental design. This chemometrical approach considers main effects as well as interactions of the influential parameters, thus conducting a more thorough investigation of the method than the common step-by-step approach. Optimisation using fractional factorial and Box Behnken Designs produced a derivatisation method featuring better yield than previously published methods while in many cases requiring less reagents and shorter reaction times.