University of North Florida
Browse the Citations
-OR-

Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

View Stuart Chalk's profile on LinkedIn

Electrode

Citations 2

"Electrochemical Oxidation And Determination Of Heparin At Electrodes Modified With Ruthenium Oxide Or Copper Oxide"
Electroanalysis 1997 Volume 9, Issue 9 Pages 675-684

Notice (8): Undefined variable: uid [APP/View/Elements/citation.ctp, line 40]
Krzysztof Lewinski, Yun Hu, Charles C. Griffin, James A. Cox

Abstract: The electrochemical oxidation of full-size heparin (13-15 kDa) is demonstrated in 1 M H-3PO-4 at a glassy carbon electrode coated with a ruthenium oxide film. The pathway apparently is analogous to chemical oxidation by periodate. By comparison to currents from inorganic species. it is apparent that only about 2 electrons per mole are involved. Flow injection analysis (FIA) allowed determinations down to 2 µM heparin, but the calibration plot was nonlinear. Low molecular weight heparin (5-6 kDa) was not electroactive with this system. In basic solution at a glassy carbon electrode that is modified with a film of Cu-2O, both full-size and low molecular weight heparin are oxidized. The pathways involved oxidative desulfation and attack on saccharide units with evolution of CO-2. Linear calibration plots which extended into the sub µM level were obtained by FIA. The detection limits, which were based on a value of 3 for the ratio of the signal to the standard deviation of replicates, were 9 nM for full-size and 20-30 nM for various low molecular weight heparin samples.
Heparin Apparatus Detector

"Anion-exchange Chromatography With Electrochemical Detection Of Alditols And Sugars At A Cu2o-carbon Composite Electrode"
J. Chromatogr. A 1997 Volume 773, Issue 1-2 Pages 115-121

Notice (8): Undefined variable: uid [APP/View/Elements/citation.ctp, line 40]
Tommaso R. I. Cataldia,*, Diego Centonzea, Innocenzo G. Casellaa and Elio Desimonib

Abstract: An anion-exchange column coupled with an amperometric sensor was used for the quantitative analysis of alditols and simple sugars. The sensing electrode is composed of cuprous oxide dispersed in a graphite powder-polyethylene composite matrix. The resulting Cu2O-carbon composite electrode is stable in alkaline media and possesses good sensitivity, wide linear dynamic ranges and low detection limits for alditols, mono- and disaccharides. Alditols and carbohydrates are weakly ionizable compounds, so an anion-exchange column was employed for their chromatographic separation with an alkaline eluent. The separation problems due to the presence of low but uncontrolled amounts of carbonate in the alkaline mobile phase have been largely solved by the addition of Ca2+ or Ba2+ at a millimolar level and the consequent formation of carbonate insoluble salts. Using this strategy, the alkaline eluent provides improved separations without compromising the column's lifetime, electrode performance and chromatographic system. Under the optimal operating conditions, the detection limits of D-sorbitol, D-mannitol and D-glucose were 50, 40 and 80 pmol, respectively, with a linear concentration range up to 5 mM. Examples of applications, which include the separation and detection of D-sorbitol, D-mannitol and common sugars present in food samples, are illustrated. 35 References
Alditols Sugars Sorbitol d-Mannitol d-Glucose Food Optimization