Ligand Exchange

CE enantiomeric resolution was first established, through a procedure named ligand exchange. This is based on metal chelate complexation with copper or zinc at the centre of the complex. It was directed towards amino acids, which as dansyl-labelled derivatives were resolved through initially interacting copper (Cu(II)) and l-histidine in the run buffer and then forming a ternary metal complex with an enantiomer of a chiral amino acid. In an enantiomeric mixture the metal complexes can have differential stability, and therefore mobility differences between the enantio-mers result. In the case above, a neutral pH buffer was used, which gives a positively charged metal-histidine interaction and the enantiomer forming the higher stability complex migrates faster. One drawback of this procedure is the requirement that the amino acid in the metal-amino acid interaction has to be of very high purity to stop enantiomeric impurities being introduced into the assay. Following the initial research, the same group impressively resolved 14 racemic amino acids by this procedure where the complex was Cu(II)-aspartame. At present the procedure is limited to amino acids, with some extension to peptides and additional separations, and most applications appeared in the early years of CE.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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