Tests Characterize Copper, Zinc Bis-Glycinates

COLLEGE STATION, TexasCopper and zinc bis-glycinates have unique crystalline structure and a polymeric nature, confirmed a recent study (J Coord Chem. 2010;63(19):3335-47. DOI: 10.1080/00958972.2010.514336). Researchers from Texas A&M University in cooperation with a team from Albion Advanced Nutrition, Clearfield, Utah, noted metal amino acid chelates have been found in previous studies to have improved bioavailability compared to traditional inorganic mineral salts. However, there has been some confusion regarding the chemical composition and structure of metal amino acid chelates. The research team therefore sought to characterize the crystal structure, carbon, nitrogen and metal content of copper and zinc bis-glycinates using a variety of testing and analytical techniques.

Copper and zinc glycinates were prepared using copper sulfate pentahydrate and Zn(OH)2. The team first used X-ray crystallography to confirm presence and structure of the bis-glycinate compounds. In the copper glycinate, two glycinate ligands chelated the copper through nitrogen and one carboxylate oxygen; the arrangement of the ligands was cis with both nitrogens on the same side. In the case of zinc glycinate, there were two unique zincs, each chelated by two glycinates in a trans arrangement. Mass spectra was used to optimize analysis of the protonated molecular ion of the metal amino acid chelates, which confirmed the polymeric nature of the compounds.