Metal Complexation and Isomer Differentiation by Mass Spectrometry

CABRERA GABRIELA M.

Conferencia; IV Congresso da BrMass; 2011

Sociedad Brasileña de Espectrometría de Masa

Complexation with metal ions in solution, followed by efficient transport of charged complexes to the gas phase by electrospray ionization (ESI), has been recognized as a promising method for the ionization of a variety of analytes, including those that are not directly amenable to ESI. Particularly, differentiation by mass spectrometry of isomers and their derivatives is relevant in the development of methods for their simultaneous analysis. In this talk, the results obtained with the use of different metal cations for isomer complexation will be discussed. The studied compounds were of diverse chemical nature like pyridine and pirazine N-oxides and dihydroxyarenes. Among the metals, transition and alkaline earth metal ions have been used. Mass spectra obtained with the different metal cations exhibited several characteristic species for each isomer thus allowing the differentiation. Quantum chemical calculations were performed in order to gain insight into the different complexation of calcium(II) with some isomers. The practical application of metal complexation in LC/ESI-MS as a detection method for the differentiation of dihydroxyarene isomers was also tested. The metal solution was added post-column at the interface between the LC column and the source. Thus, with a simple LC/ESI-MS experiment, significant structural information can be derived from the spectra obtained with the addition of different metals.