The Electrochemical Study Of Bilirubin And Langmuir-Blodgget Of Bilirubin

Bilirubin is a very important biologic compounds. The Electrochemical study of bilirubin and Langmuir-Blodgget of bilirubin is significant. The electrochemical behaviors of Y-type bilirubin-Phosphatisgylethanolamine mixed Langmuir-Blodgett (LB) film and bilirubin-M on glass carbon electrode were investigated with Cyclic Voltammetry and Differential Pulse Voltammetry. It's shown that the bilirubin LB film has a cathodic peak at +420mV in 0.2 molIL HAc-Na.Ac-50%EtOH (pH=5.4). Effects of such condition as deposition rate (u), deposition pressure (), molar ratio of bilirubin to phosphaticlylethanolamine (nBR:nDppE), the number of LB layers (NLB) on peak current have been studied. The electrochemical behavior of bilirubin LB film formed under the optimized condition were compared with that of bilirubin LB film in solution containing metal ions, that of bilirubin and in aqueous solution, which indicated that the peak potential of bilirubin LB film moves to positive with the stability of metal complex. Also, the difference of the electrochemical behavior of bilirubin in ordered LB film was compared with those in cast film and aqueous solution. We studied the electrochemical behaviors of bilirubin in aqueous solution and established the quantitative analysis of bilirubin determination with differential pulse voltammetry. In 0.2 mol/L HAc-NaAc-50%EtOH and 1/15 moIIL KH2PO4-Na2HPO4 solution, the linear range of bilirubin is 6.25>(i04.00X lO5molIL and 5.OOX 1O8 3.00 X lO4mol/L, respectively. The detection limitation is 5.00 X lO8molIL and 5.00 X 1 O9mol/L respectively. After condition optimization, we determined the content of bilirubin in Zhongshengwan and Niuhuangjiedupian, the content is 0.108% and 0.086% respectively, which has the consistent result with the standard method recorded in pharmacopoeia, the recovery of which is 96.6?01.4% and 98.6-104.2% respectively. The electrocatalyzed kinetics of oxygen reduction in bilirubin-cbloroform system was studied using cyclic voltanimetry, potential step and rotating disk electrode. The results indicate that the peak current of reduction increases with the sweep speed u. The peak current of peak I has linear relation with u, otherwise peak current ofpeak II has linear relation with square root of U. Based on the slope of Q-t curve obtained from potential step experiment, the electron transfer number can be calculated to be 2.55 and 3.79. Based on the slope of I,, ca 2 curve obtained from rotating disk electrode experiment in different potentials, the electron transfer number was calculated to be 2.07(-0.12V), 2.49(-0.15V), 3.98(-0.12V), and 3.90 (-0.48V),respectively.