Constant current chronopotentiometric stripping of sulphated polysaccharides
We show that electrochemically inactive molecules of polysaccharide (PS), if carrying sulphated groups (e.g. iota-carrageenan and dextran sulphate) produce in buffered solutions two well-developed chronopotentiometric peaks H-PS and H-PS' (due to catalytic hydrogen evolution) at hanging mercury drop electrode. Peak H-PS of iota-carrageenan displayed a striking increase at negative accumulation potentials, which was tentatively explained by uncoiling the PS double-helical structure at these potentials. Nanomolar concentrations of iota-carrageenan can be determined at moderate accumulation times. (C) 2009 Elsevier B.V. All rights reserved.