Ligand-exchange chromatography of amino sugars and amino acids on copper-loaded silylated controlled-pore glass

Determination of enantiomers of amino acids by reversed phase high performance liquid chromatography

“…Instead the hydrophobic part consists of a cyclohexyl ring. AspcHex has two major advantages: (a) Owing to the absence of a phenyl group, the background of the detector signal should be smaller than with Aspartame, (b) Because of the low background absorbance, nonaromatic amino acids can be detected by virtue of the fact that they form with Cu a five-membered ring complex which strongly absorbs UV radiation at around 230 nm (21). This last point is of cardinal importance: the presence of Asp-cHex-Cu(II) complex in the mobile phase is found to allow not only the separation of the amino acid enantiomers but also their detection.…”

Ion exchange and liquid column chromatography

“…Typically the stationary phase is a cation exchanger loaded with metal ions; amines or amino acids are absorbed by coordination and selectively displaced by ammonia. Amino acids were recovered from seawater by a copper-loaded chelating resin (151); copper-loaded chitosan separated four amino acids (349); amino acids and amino sugars were separated on copper-loaded silylated glass (326); a copper-loaded porous silica gave excellent separations of 8 amino acids with ammonia in aqueous acetonitrile as eluent (60, 420); a copper-loaded, dithiocarbamate-bonded silica packing gave separations of 22 amino acids and many aromatic amines, with plate heights of 0.5 mm (68). Ammonia solutions containing Cu(II) were used as eluents, and alkaline attack on the silica was minimized, but not eliminated, by using mixed aqueous-non-aqueous solvents and low ammonia concentrations.…”