Evaluation of buffer solutions and additives for capillary electrophoresis separation and matrix assisted laser desorption/ionization (MALDI) mass spectrometry analysis of antibiotics

VALERIA H. SPRINGER; PATRIK EK; JOHAN JACKSÉN; ADRIANA G. LISTA; ASA EMMER

Congreso; XVIII Encontro Luso-Galego de Quimica; 2012

Fluoroquinolones (FQs) are used for the treatment of infections in human and veterinary medicine. Their massive use has become a serious problem because residues can be found in the environment and in food of animal origin, which may be directly toxic or cause human pathogens resistant to antibiotics and possible allergic hypersensitivity reactions in humans1. Taking this into account, several organisations (e.g. FDA, EU and WHO, among others) have established tolerance levels for these compounds in different samples in order to ensure the human health2. Nowadays, the development of different methodologies of control is necessary considering the current legislations and the new international demands. The use of capillary electrophoresis (CE) provides fast separations and high resolving power employing low consumption of sample and reagents3. Also, matrix assisted laser desorption/ionization (MALDI) is a soft ionization technique that shows some advantages over other ionization techniques due to few fragment ion signals and low sample consumption4. In the present work, an off-line CE-MALDI-mass spectrometry (MS) method for the determination of FQs is developed. The effect of several buffer solutions, surfactants and organic additives commonly used in capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) was evaluated for the determination of these antibiotics by MALDI-TOF-MS. With this aim, cationic and non-ionic surfactants, carboxymethyl-ß-cyclodextrin and different organic solvents were tested as buffer additives and the results on the CE performance and MALDI-MS analysis were studied. It was shown that ammonium phosphate solution containing 2 mM CTAB at pH 3 was compatible with both techniques. Satisfactory resolution in the CE separation and mass spectra with good signal intensity were obtained, without interference from the surfactant in the mass range of the analytes. The future coupling between CE and MALDI-MS represents a powerful tool for separation and quantification of FQ compounds, which makes this method suitable for the control of this kind of antibiotics. In the present work, an off-line CE-MALDI-mass spectrometry (MS) method for the determination of FQs is developed. The effect of several buffer solutions, surfactants and organic additives commonly used in capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) was evaluated for the determination of these antibiotics by MALDI-TOF-MS. With this aim, cationic and non-ionic surfactants, carboxymethyl-ß-cyclodextrin and different organic solvents were tested as buffer additives and the results on the CE performance and MALDI-MS analysis were studied. It was shown that ammonium phosphate solution containing 2 mM CTAB at pH 3 was compatible with both techniques. Satisfactory resolution in the CE separation and mass spectra with good signal intensity were obtained, without interference from the surfactant in the mass range of the analytes. The future coupling between CE and MALDI-MS represents a powerful tool for separation and quantification of FQ compounds, which makes this method suitable for the control of this kind of antibiotics.