Use of cyclofructan as a potential complexing agent in capillary electrophoresis

A novel selective complex-forming agent for metal cations in capillary electrophoresis (CE) was investigated. The complex former is cyclofructan (cyclic -fructohexaose or cycloinulohexaose), obtained from enzymatic conversion of inulin using the enzyme, cycloinulo-oligosaccharide fructanotransferase (CFTase), obtained from a strain of Bacillus circulans, MCI-2554. It has a circular hexameric structure resembling that of 18-crown-6. Complex formation with a number of cations was determined using CE with indirect UV detection at 200 nm and a background electrolyte consisting of 10 mM 2-aminopyridine, buffered at pH 4.50 with acetic acid. Cyclofructan was added to the electrolyte at different concentrations and complexation constants with a number of cations were determined. Permethylated cyclofructan was compared with 18-crown-6 in a 50% aqueous methanol buffer