| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 96 === In this study, successful fabrication of the screen-printed carbon electrode electro-deposited with polypyrrole film, abbreviated as PPy-C modified electrode, to detect cysteine with a concentration range from 0.025 mM to 0.2 mM in solution was achieved. Varying amount of cysteine present initially and conjointly with pyrrole during electropolymerization significantly changes the sensitivity, imprinting factor and adsorption capacity of the PPy-C modified electrode. With cyclic voltammogram obtained from 0.2 mM cysteine solution, the sensing potential of cysteine at the PPy-C modified electrode was determined at 0.7 V (vs. Ag/AgCl, 3 M KC1). The PPy-C modified electrode doped with cysteine (0.5 mM initially present) gave a maximum sensitivity as 89.80 uA˙cm-2˙mM-1 and an imprinting factor as high as 1.27 when 0.15 mM cysteine in solution was sensed. Furthermore, the same PPy-C modified electrode at the same sensing potential could be used in detecting mixtures of cysteine and homocysteine, from which the selectivity of cysteine was 1.11. Langmuir isotherm was employed successfully in accounting for the adsorption behavior of cysteine on the PPy-C electrodes. Likewise, the PPy-C modified electrode made from 0.5 mM cysteine initially present in electropolymerization of polypyrrole rendered the maximum saturated adsorption capacity.
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