Identification of Aluminum Species in an Aluminum-accumulating Plant, Hydrangea (Hydrangea macrophylla), by Electrospray Ionization Mass Spectrometry

Abstract

The use of electrospray ionization mass spectrometry (ESI-MS) in negative ion mode was investigated as a direct probe for identifying Al species in Al-accumulating hydrangea (Hydrangea macrophylla) samples. Cell sap solutions of hydrangea leaves were purified using Sephadex G-10 liquid chromatography and each fraction was analyzed using ESI-MS and ESI-MS/MS to identify Al species. In hydrangea leaves, a 1:1 Al-citrate complex was found as [AlH_-1cit]^- (m/z 215), where H₃cit denotes citric acid. This result is consistent with that of Ma et al. who used ²⁷Al-NMR.