Full text
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| Author(s): |
Thiago Regis Longo Cesar da Paixão
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2004-03-12 |
| Examining board members: |
Mauro Bertotti;
Silvia Maria Leite Agostinho;
Orlando Fatibello Filho
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| Advisor: | Mauro Bertotti |
| Abstract | |
A copper disc working electrode in alkaline solutions was demonstrated to act as a suitable amperometric sensor for ethanol determination at +0.6 V vs Ag/AgCl. The participation of free-soluble Cu(III) species in the electrocatalytic process involving the anodic oxidation of ethanol has been demonstrated by rotating ring-disc electrode voltammetry. The influence of the pretreatment potential on the anodic signal was investigated and a correlation with the morphology of the electrode surface characterized by Energy Dispersive X-Ray Spectroscopy (EDS) indicated that the Cu(III) species is originated from the oxidation of a CuO layer. Ethanol measurements were performed in the amperometric mode at 0.6 V (vs Ag/AgCl). The repeatability of the measurements for a 0.05 % aqueous ethanol solution was estimated as 3 %, and the detection and quantification limits were determined as 0.005 % and 0.01 %, respectively. At the optimum experimental conditions, the amperometric sensor was used to monitor the concentration of ethanol in breath (BrAC), which was conveniently collected in a rubber air balloon (volume = 3 L) and introduced in a 1 mol L-1 NaOH working solution (volume = 10 mL). The sensor can measure a person\'s breath ethanol over the concentration range 0.26 - 130 mg L-1 by operating it according to an established protocol, of which the analytical parameters are specified by the Brazilian Legislation for BrAC measurements in drivers. The rate of ethanol degradation in the body was followed, and the results agree with predictions in the literature. Methodologies for the determination of dipyrone, glucose and ascorbic acid were also developed by using Cu and Au electrodes. Features of a dual-band electrochemical cell were investigated towards the development of a generator-collector system, which was employed in titrations with electrogenerated iodine. (AU) | |
| FAPESP's process: | 01/11589-8 - Use of Cu and Au electrodes in electroanalysis: amperometric detection of ethanol in exhaled air and other applications |
| Grantee: | Thiago Regis Longo Cesar da Paixão |
| Support Opportunities: | Scholarships in Brazil - Master |