This work describes the preparation of a glassy carbon electrode (GCE) modified with molecularly imprinted polymer (MIP) and multiwalled carbon nanotubes (MWCNTs) for determination of carvedilol (CAR). Electrochemical behavior of CAR on the modified electrode was evaluated using cyclic voltammetry. The best composition was found to be 65% (m/m) of MIP. Under optimized conditions (pH 8.5 in 0.25 mol·L −1 Britton-Robinson buffer and 0.1 mol·L −1 KCl) the voltammetric method showed a linear response for CAR in the range of 50-325 µmol·L −1 (R = 0.9755), with detection and quantification limits of 16.14 µmol·L −1 and 53.8 µmol·L −1 , respectively. The developed method was successfully applied for determination of CAR in real samples of pharmaceuticals. The sensor presented good sensitivity, rapid detection of CAR, and quick and easy preparation. Furthermore, the material used as modifier has a simple synthesis and its amount utilized is very small, thus illustrating the economic feasibility of this sensor.

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This work describes the development of an electrochemical sensor that was used in the determination of ethinyl estradiol (EE) in pharmaceutical formulations, river water, and milk using the square wave voltammetry technique. Studies were carried out using different carbonaceous materials (multiwalled carbon nanotubes, reduced graphene oxide Reduced graphene oxide, graphite) and different metallic phthalocyanines (cobalt, iron and manganese). Based on these studies it was possible to obtain the best system for the construction of the sensor. The device was obtained by the chemical modification of a glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs) and cobalt phthalocyanine (CoPc). The materials were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Under conditions previously optimized for the proposed method, an analytical curve was constructed, presenting linearity in a range of 2.50-90.0 µmol L −1 (R = 0.990), with detection limit of 2.20 µmol L −1 and quantification of 2.50 µmol L −1 . The validation of the methodology for the determination of EE using GCE-MWCNTs-CoPc was performed, being accurate, precise, stable and sensitive. The recovery of ethinyl estradiol in the sample of pharmaceutical formulation was 103.93%, in the samples of river water ranged from 92.75% to 96.47%, and in the milk sample was from 88.00% to 96.20%. Thus, the proposed method presented a viable alternative for the determination of ethinyl estradiol in the quality control of pharmaceutical and food formulations as well as in environmental control.

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Pesticides are chemical or biological substances widely used in agriculture in order to protect crops from attack by pests. However, many pesticides have been banned due to the fact that their compositions provide the formation of cancerous tumors and the appearance of other problems for human health, which makes it necessary to control and quantify their residues in food, water and soil. Thus, the development of techniques for the quantification and control of pesticides and their residues in food, water and soil is of essential importance. Among techniques that can be used for the analysis of these pesticides, the development of electrochemical sensors is an area of great interest for electroanalytical, and its use becomes advantageous due to characteristics such as high sensitivity, selectivity and stability, in addition, few residues are generated, have moderate cost and easy automation. One of the purposes in which sensors are widely used is in the determination of substances of environmental interest, providing control over the use of pesticides and especially their residues, whose presence of certain amounts in food, water and soil can be considered harmful to the health of living beings and the environment. Thus, this review aims to show trends in the use and application of electrochemical sensors for the determination of various pesticides in real samples. Os pesticidas são substâncias químicas ou biológicas muito utilizadas na agricultura com o intuito de proteger as lavouras do ataque de pragas. Entretanto, muitos pesticidas tiveram o uso proibido devido ao fato de suas composições proporcionarem a formação de tumores cancerígenos e o surgimento de outros problemas para saúde humana, o que torna necessário o controle e quantificação de seus resíduos nos alimentos, água e solo. Dessa forma, o desenvolvimento de técnicas para a quantificação e controle de pesticidas e seus resíduos em alimentos, água e solo, é de essencial importância. Dentre técnicas que podem ser utilizadas para a análise desses pesticidas, o desenvolvimento de sensores eletroquímicos é uma área de grande interesse da eletroanalítica, e seu uso torna-se vantajoso devido características como alta sensibilidade, seletividade e estabilidade, além disso, são gerados poucos resíduos, apresentam custo moderado e fácil automação. Um dos propósitos em que os sensores são amplamente utilizados é na determinação de substâncias de interesse ambiental, proporcionando o controle sobre a utilização de pesticidas e principalmente de seus resíduos, cuja presença de determinadas quantidades em alimentos, água e solo podem ser considerados prejudiciais à saúde de seres vivos e ao meio ambiente. Assim, esta revisão tem por objetivo mostrar as tendências sobre o emprego e aplicação de sensores eletroquímicos para a determinação de variados defensivos agrícolas em amostras reais.