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

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 heptafluorobutyrylimidazole. 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. (C) 1998 Elsevier Science B.V. All rights reserved.