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| Author(s): |
Cecília de Carvalho Castro e Silva
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2011-01-08 |
| Examining board members: |
Lauro Tatsuo Kubota;
Aldo José Gorgatti Zarbin;
Cláudia Longo
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| Advisor: | Lauro Tatsuo Kubota |
| Abstract | |
This work describes the fabrication of an amperometric sensor for electrocatalytical detection of cysteine. The developed sensor is based on a functional platform for complexing copper ions on multi-walled carbon nanotubes (MWCNTs) modified with poly-4-vinylpyridine through an in situ reaction of polymerization. A multivariate analysis using a central composite design to investigate the surface modification of glassy carbon electrode (GCE) was employed to optimize the experimental variables. The established optimal conditions for the concentration of MWCNTs-PVP dispersed nanocomposite were, 6,00 mg L, 50 mmol L of concentration CuCl2 and around 83 min. for complexation of copper ions. The platform was characterized performing scanning electron microscopy (SEM), energy dispersive x-ray (EDX), electrochemical impedance spectroscopy (EIS), chronoamperometry and cyclic voltammetry analyses. The obtained values for the kinetic constants for heterogeneous electron transfer rate (ks) and for chemical reaction (kobs) between Cu and cysteine were 5.78 s and 6.96 L mol s, respectively. The analytical curve showed a linear range for detecting cysteine in concentrations from 5 to 60 mmol L. The detection and quantification limits obtained were 1.50 and 5.00 mmol L, respectively. Moreover, the response time of the ECV/MWCNTs-PVP/Cu sensor was 0.1 s. The application of the sensor to detect cysteine in nutritional supplement showed results statistically equal (0.95 confidence level) to those obtained with official methods (AU) | |
| FAPESP's process: | 09/02908-4 - The use of modified carbon nanotube in the electrochemical sensors development to be applied in biological interess samples. |
| Grantee: | Cecilia de Carvalho Castro e Silva |
| Support Opportunities: | Scholarships in Brazil - Master |