Electrospray ionization mass spectrometry (esi-ms) has been applied to the study of solution equilibria between aluminum(III) ion and some fluoroquinolone family members – fleroxacin and moxifloxacin. At metal to ligand concentration ratio 2:1 to 1:3 (TAl = 2.5 x 10-5 mol/L) in the pH range 3.0 to 6.0 two main complexes of the composition AlL and AlL2 are formed in both studied systems in agreement with previous potentiometric, uv and nmr study of these systems. Polynuclear complexes were not detected. The complexes showed little fragmentation (mainly decarboxylation) with different deprotonated species which could not be identified. Relative abundance of complexes in solution was calculated from the corresponding signal intensities and compared with HPTLC and previously obtained potentiometric data. The HPTLC data indicate two main peaks which were ascribed to the formed complexes; calculated relative fractions of complexes on the basis of peak areas were in good correlation with esi-ms data.
STUDY OF SOLUTION EQUILIBRIA BETWEEN ALUMINUM(III) ION AND SOME FLUOROQUINOLONE FAMILY MEMBERS
DI MARCO, VALERIO
2011
Abstract
Electrospray ionization mass spectrometry (esi-ms) has been applied to the study of solution equilibria between aluminum(III) ion and some fluoroquinolone family members – fleroxacin and moxifloxacin. At metal to ligand concentration ratio 2:1 to 1:3 (TAl = 2.5 x 10-5 mol/L) in the pH range 3.0 to 6.0 two main complexes of the composition AlL and AlL2 are formed in both studied systems in agreement with previous potentiometric, uv and nmr study of these systems. Polynuclear complexes were not detected. The complexes showed little fragmentation (mainly decarboxylation) with different deprotonated species which could not be identified. Relative abundance of complexes in solution was calculated from the corresponding signal intensities and compared with HPTLC and previously obtained potentiometric data. The HPTLC data indicate two main peaks which were ascribed to the formed complexes; calculated relative fractions of complexes on the basis of peak areas were in good correlation with esi-ms data.
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