title: Electrochemical determination of heparin using methylene blue probe and study on competition of Ba2+ with methylene blue for binding heparin.
abstract: Cyclic voltammetric investigation of the interaction of methylene blue (MB) with heparin (hep) at a gold electrode is presented. The combination of MB with heparin formed a nonelectroactive complex MB-hep, which resulted in the peak current decrease of MB. The anodic peak current difference of MB was found to be proportional to the concentration of heparin in the range of 0.666-64.5microg mL(-1) with a detection limit of 270ng mL(-1) and a satisfactory result was obtained for the determination of heparin in injection samples. The equilibrium constant for MB-hep complex was calculated to be 7.32x10(5). The dynamic process of competition of Ba(2+) with methylene blue for binding heparin was monitored using quartz crystal microbalance (QCM) technique. The reaction rate constant between Ba(2+) and MB-hep was estimated to be 0.0022s(-1).
authors.affiliation: State Key Laboratory of Chemo/Biological Sensing and Chemometrics, Hunan University, Changsha 410082, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Tan
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
authors.forename: Qingji
authors.initials: Q
authors.lastname: Xie