Electrospray ionization mass spectrometry combined with the ultra high performance liquid chromatography in the analysis of in vitro formation of chlorophyll complexes with copper and zinc

The aim of this study was to obtain a more accurate insight into the interaction of the major photosynthesis pigment, chlorophyll (Chl), with cop- per(II) and zinc(II) in solution using flow injection analysis combined with electrospray ionization mass spectrometry (FIA-ESI-MS), as well as combined with ultra high performance liquid chromatography with DAD detection (UHPLC-DAD). These interactions may potentially, but not necessarily, lead to the formation of Cu-Chl and Zn-Chl complexes of two different types, which has a large number, at least, disfunctional implications in the plant world. The results based on analysis of full-scan and MS/MS spectra, with and without UHPLC chromatograms, confirmed the formation of a "central type" Cu-Chl complex and a "central type" Zn-Chl complex, as well as proved the formation of a "peripheral" Zn-Chl complex, the latter one originating from a very weak coordinative interaction at the edge of the Chl structure. The employed techniques appeared to be efficient and reliable tools for studying the formation and stability of heavy metals complexes with chlorophyll, at least in vitro, with a considerable possibility for an assessment of real bioenvironmen- tal behavior.