Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode
A flow injection system using an unmodified gold screen-printed electrode was employed for total phenol determination in black and green teas. In order to avoid passivation of the electrode surface due to the redox reaction, preoxidation of the sample was realized by hexacyanoferrate(III) followed b...
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| Format: | Article |
| Language: | English |
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Wiley
2010-01-01
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| Series: | International Journal of Analytical Chemistry |
| Online Access: | http://dx.doi.org/10.1155/2010/143714 |
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| author | Ivanildo Luiz de Mattos José Heraclito Zagal |
| author_facet | Ivanildo Luiz de Mattos José Heraclito Zagal |
| author_sort | Ivanildo Luiz de Mattos |
| collection | DOAJ |
| description | A flow injection system using an unmodified gold screen-printed electrode was employed for total phenol determination in black and green teas. In order to avoid passivation of the electrode surface due to the redox reaction, preoxidation of the sample was realized by hexacyanoferrate(III) followed by addition of an EDTA solution. The complex formed in the presence of EDTA minimizes or avoids polymerization of the oxidized phenols. The previously filtered tea sample and hexacyanoferrate(III) reagent were introduced simultaneously into two-carrier streams producing two reproducible zones. At confluence point, the pre-oxidation of the phenolic compounds occurs while this zone flows through the coiled reactor and receives the EDTA solution before phenol detection. The consumption of ferricyanide was monitorized at 360 mV versus Ag/AgCl and reflected the total amount of phenolic compounds present in the sample. Results were reported as gallic acid equivalents (GAEs). The proposed system is robust, versatile, environmentally-friendly (since the reactive is used only in the presence of the sample), and allows the analysis of about 35–40 samples per hour with detection limit = 1 mg/L without the necessity for surface cleaning after each measurement. Precise results are in agreement with those obtained by the Folin-Ciocalteu method. |
| format | Article |
| id | doaj-art-32c031e983274d7a92f1e22a7e82768e |
| institution | Kabale University |
| issn | 1687-8760 1687-8779 |
| language | English |
| publishDate | 2010-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | International Journal of Analytical Chemistry |
| spelling | doaj-art-32c031e983274d7a92f1e22a7e82768e2025-02-03T01:31:03ZengWileyInternational Journal of Analytical Chemistry1687-87601687-87792010-01-01201010.1155/2010/143714143714Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed ElectrodeIvanildo Luiz de Mattos0José Heraclito Zagal1Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Sucursal Matucana, Santiago 9170022, ChileDepartamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Sucursal Matucana, Santiago 9170022, ChileA flow injection system using an unmodified gold screen-printed electrode was employed for total phenol determination in black and green teas. In order to avoid passivation of the electrode surface due to the redox reaction, preoxidation of the sample was realized by hexacyanoferrate(III) followed by addition of an EDTA solution. The complex formed in the presence of EDTA minimizes or avoids polymerization of the oxidized phenols. The previously filtered tea sample and hexacyanoferrate(III) reagent were introduced simultaneously into two-carrier streams producing two reproducible zones. At confluence point, the pre-oxidation of the phenolic compounds occurs while this zone flows through the coiled reactor and receives the EDTA solution before phenol detection. The consumption of ferricyanide was monitorized at 360 mV versus Ag/AgCl and reflected the total amount of phenolic compounds present in the sample. Results were reported as gallic acid equivalents (GAEs). The proposed system is robust, versatile, environmentally-friendly (since the reactive is used only in the presence of the sample), and allows the analysis of about 35–40 samples per hour with detection limit = 1 mg/L without the necessity for surface cleaning after each measurement. Precise results are in agreement with those obtained by the Folin-Ciocalteu method.http://dx.doi.org/10.1155/2010/143714 |
| spellingShingle | Ivanildo Luiz de Mattos José Heraclito Zagal Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode International Journal of Analytical Chemistry |
| title | Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode |
| title_full | Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode |
| title_fullStr | Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode |
| title_full_unstemmed | Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode |
| title_short | Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode |
| title_sort | detection of total phenol in green and black teas by flow injection system and unmodified screen printed electrode |
| url | http://dx.doi.org/10.1155/2010/143714 |
| work_keys_str_mv | AT ivanildoluizdemattos detectionoftotalphenolingreenandblackteasbyflowinjectionsystemandunmodifiedscreenprintedelectrode AT joseheraclitozagal detectionoftotalphenolingreenandblackteasbyflowinjectionsystemandunmodifiedscreenprintedelectrode |