title: Thin layer coulometry based on ion-exchanger membranes for heparin detection in undiluted human blood.
abstract: We explore here for the first time a potentially calibration-free methodology for the detection of protamine (and, by titration, heparin) in undiluted human blood in the therapeutic concentration range from 20 to 120 mg L(-1). The use of a thin layer sample (5.8 μL) confined between a tubular protamine selective membrane (inner diameter, 600 μm) and a Ag/AgCl wire (diameter 400 μm) achieves an exhaustive depletion from the sample. Coulometry detection was chosen for the interrogation of the thin layer, employing a double pulse technique with 120 s for each pulse. Protamine calibration curves were recorded at physiological concentrations and in undiluted human blood. A linear relationship was obtained in both cases, but a diminished sensitivity was observed in contact with blood, which is explained with a partial passivation of the inner Ag/AgCl element. Heparin-protamine titrations were performed in undiluted human blood samples, mimicking the final application with patients undergoing critical care. The observed values correlate satisfactorily with those of an alternative technique, so-called flash-chronopotentiometry on planar membranes.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Geneva , Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
authors.forename: Gastón A
authors.initials: GA
authors.lastname: Crespo
authors.forename: Majid Ghahraman
authors.initials: MG
authors.lastname: Afshar
authors.forename: Denis
authors.initials: D
authors.lastname: Dorokhin
authors.forename: Eric
authors.initials: E
authors.lastname: Bakker
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D002138:Calibration; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D006493:Heparin / Q000097:blood*; D006801:Humans; D007474:Ion Exchange; D008567:Membranes, Artificial; D019095:Point-of-Care Systems
chemical_list: D008567:Membranes, Artificial; D006493:Heparin