Determinação eletroquímica do agrotóxico tiabendazol extraído e pré-concentrado em amostras de tomate pela técnica de ponto nuvem usando eletrodo de diamante dopado com boro
Data
2019-03-29
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
In Brazil, there is a significant consumption of tomatoes and, according to the report of the
Program of Analysis of the Residues of Agrochemicals in Food (PARA) available by ANVISA,
the tiabendazole (TBZ) fungicide was detected in some tomato samples analyzed. The
detection of this substance is considered to be prohibited, since the TBZ is authorized only for
application in seeds of the plant and, therefore, could not be found in fruits. Thus,
electrochemical methods can be used for the determination of pesticides in complex samples
and in low concentration levels, because they produce fast and reliable measurements,
consuming small amounts of reagents. In this work, a procedure for the electroanalytical
determination of TBZ fungicide in tomato fruits using boron-doped diamond electrode (BDD)
was developed and validated using the cloud extraction and preconcentration (CPE)
technique. The analytical technique used in this determination was the High Performance
Liquid Chromatography coupled to an electrochemical detector (HPLC-EC), by the use of the
BDD electrode. In order to evaluate the main variables of the CPE process, it was used a 24
complete factorial planning to optimize the parameters. The CPE optimized condition was
achieved by the use of Tergitol (19% V/V), NaCl (0.83 g), ultrasonic stirring time of 15 min
and temperature of 36 °C. Under these conditions, the preconcentration factor obtained was
5.7. The limits of detection and quantification obtained were 2.7 × 10-8 mol L-1
and 5.5 × 10-8
mol L-1
, respectively. The average recoveries obtained in 3 days were satisfactory, varying
between 80.7% and 115.1%, which demonstrates the good accuracy of the developed
method. In the application of the method in commercial tomatoes, TBZ was detected in one of the samples analyzed. The differential pulse voltammetry (DPV) technique was also
investigated for the electroanalytical determination of TBZ fungicide in tomato fruit (extracted
and pre-concentrated by CPE) using BDD electrode in order to increase the analytical
frequency. The use of DPV technique increased the analytical frequency by approximately 90 times compared to the HPLC/EC technique.
Descrição
Palavras-chave
Tiabendazol, Extração por ponto nuvem, CLAE/EC, VPD, Eletrodo de diamante, Thiabendazole, Cloud oint extraction, HPLC-EC, DPV, Diamond electrode
Citação
CAIXETA NETA, A. Determinação eletroquímica do agrotóxico tiabendazol extraído e pré-concentrado em amostras de tomate pela técnica de ponto nuvem usando eletrodo de diamante dopado com boro. 2019. 101 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2019.