Study on coordination of selenoamino acids with Ag+ at silver nitrate-modified carbon paste electrode.
Surface Ag+ ions forming complexes with the amino (selenoamino) acids compounds have been studied at a silver nitrate-modified carbon paste electrode (AgNO3/CPE). The carboxyl, amidogen and selenium of selenoamino acids could coordinate with Ag+. The coordinating sites of Ag+-SeCys and Ag+-SeMet on electrode surface have been studied in the range of pH value from 1.0 to 12.0. The coordinating sites of Ag+-SeCys and Ag+-SeMet are due to the different configuration and electronegative charge of amino acids in different acidity. Increase of the coordination number of adsorbed species increases the average lifetime of these species on the surface, and hence causes that stronger bonded molecules more effectively prevent the depletion of the surface layer from the Ag+ ions. The voltammetric signals of Ag+-selenoamino acid and Ag+-sulfur-containing amino acid are stronger than those of Ag+-alanine due to the coordinating sites of AgS and AgSe bonds. Moreover, the adsorption of Ag+-selenoamino acid on electrode surface relates to different acidity.
Bai
Yan
Y
Chemistry Department of Jinan University, Guangzhou 510632, PR China. tbaiyan@jnu.edu.cn <tbaiyan@jnu.edu.cn>
Wang
Yu-dong
YD
Zheng
Wen-jie
WJ
Chen
Ya-sheng
YS
D000327:Adsorption; D000596:Amino Acids / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D018036:Selenium Compounds / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D012835:Silver Nitrate / Q000737:chemistry*; D012996:Solutions
D000596:Amino Acids; D018036:Selenium Compounds; D012996:Solutions; D012834:Silver; D002244:Carbon; D012835:Silver Nitrate