Speciation of essential nutrient trace elements in coconut water

Coconut water (Cocos Nucifera) is shown to be a source of essential elements present in the form of low-molecular weight stable complexes known for their bio-availability. The total element concentrations were in the range of 0.2-2.7, 0.3-1, 3-14 and 0.5-2 ppm for Fe, Cu, Mn, and Zn, respectively, and varied as a function of the origin of the nut and its maturity. Speciation was investigated by size-exclusion chromatography - inductively coupled plasma mass spectrometry (ICP MS), and hydrophilic interaction liquid chromatography (HILIC) - electrospray-Orbitrap MS. The metal species identified included: iron complexes with citrate and malate: Fe n ' (Cit)(3)(Mal), Fe-I(II)(Cit)(2)(Mal)(2), Fe-III(Mal)(2), glutamine: Fe-III(Glu)(2) and nicotianamine: Fe-II(NA); copper complexes with phenylanine: Cu-II(Phe)(2) and Cu-II(Phe)(3) and nicotianamine: Cu-II(NA); zinc complexes with citrate: Zn-II(Cit)(2) and nicotianamine Zn-II(NA) and manganese complex with asparagine Mn-II(Asp)(2). The contributions of the individual species to the total elements concentrations could be estimated by HILIC - ICP MS.

Automated summary

Coconut water has been shown to contain essential elements such as iron, copper, manganese, and zinc, with concentrations varying depending on the origin and maturity of the coconut. Speciation analysis revealed the presence of various metal species in coconut water, each contributing differently to the total element concentrations.