Desenvolvimento de um eletrodo de pasta de carbono quimicamente modificado com ftalocianina de ferro para a determinação de carbendazim em água potável.

Abstract

Pesticides belonging to the class of carbamate chemical compounds are widely used in agriculture due to their low cost and efficiency in controlling insects, fungi and weeds. Carbendazim (CBZ), methyl benzimidazol-2-yl carbamate, is a systemic fungicide, toxicological class III, considered dangerous to the environment, and possible mutagenic and human carcinogen. Environmental impacts are associated with the indiscriminate use of pesticide consumption in Brazil, which can lead to the occurrence of river contamination by CBZ, due to surface runoff, and may thus also be present in drinking water. According to Brazilian GM/MS Consolidation Ordinance n o 5 of September 28, 2017, and Brazilian

Ordinance GM/MS n o 888, may 4, 2021, the maximum allowed value of CBZ in drinking water

comes from the sum of CBZ and benomyl of 120 μg L -1 . Carbamate pesticides in water are monitored by chromatographic techniques. An alternative to the official method are voltammetric techniques, which are promising in the determination of pesticides. In this work, an electrochemical sensor was made of the mixture of chemically modified carbon paste with iron phthalocyanine (EPC-FePC) for the determination of CBZ in drinking water. The analyzes were performed using a potentiostat/galvanostat model PGSTART® 302N Metrohm. The techniques used were square wave voltammetry (VOQ) and cyclic voltammetry (VC). Support electrolyte Britton Robinson buffer solution (BR) pH 4,5, reference electrode silver chloride Ag/AgCl, platinum wire as against electrode and EPC-FePC as working electrode. CBZ showed better analytical response using 1% of the modifier agent (FePC). Optimized VOQ parameters: potential increment of 6 mV, frequency 60 s-1

, amplitude 70 mV. The analytical curve was

obtained using a linear range from 5,71 μg L-1

to 20,80 μg L-1

. Detection limit values (LD) of

0,00876 μg L-1

and quantification (LQ) of 0,0292 μg L-1 , R2 equal to 0,9973. The proposed method uses simplified and low cost instrumentation compared to chromatographic techniques. The surface of EPC-FePC is easy to renew, fast analysis, high sensitivity and selective for the determination of carbendazim, being promising for a future application in drinking water.