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Desenvolvimento de um sensor eletroquímico molecularmente impresso para a análise da hidroclorotiazida em águas ambientais
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Abstract(s)
A hidroclorotiazida (HCT) é um diurético amplamente utilizado no tratamento de hipertensão e retenção de líquidos. A sua presença tem sido detetada em amostras de águas ambientais, incluindo efluentes de Estações de Tratamento de Águas Residuais (ETARs). As ETARs não são capazes de eliminar eficientemente os fármacos presentes nas águas residuais, pelo que estes são novamente libertados para as águas superficiais. A União Europeia aprovou recentemente uma Diretiva que obriga a remoção da HCT pelas ETARs com uma eficiência mínima de 80 % em relação à sua carga afluente nas águas residuais municipais. Desta forma, novos métodos que permitam uma monitorização rápida, de baixo custo e portabilidade são fundamentais. Neste trabalho foi desenvolvido um sensor eletroquímico baseado num Polímero Molecularmente Impresso (MIP) para a análise de HCT, onde se usou como célula eletroquímica um elétrodo de papel impresso a jatos de tinta. Posteriormente, o elétrodo de trabalho foi modificado com tinta condutora de carbono e óxido de grafeno (GO). O sensor MIP foi construído por eletropolimerização do monómero funcional ácido 4-aminobenzóico na presença da HCT. O GO mostrou ser um nanomaterial eficiente para o aumento do sinal eletroquímico de HCT. O sensor MIP exibiu uma boa relação linear entre a concentração de HCT e a intensidade de corrente do pico de oxidação, tendo sido obtidos limites de deteção (LOD) e de quantificação de 1,8 μmol L-1 e 5,7 μmol L-1, respetivamente. O sensor MIP desenvolvido apresenta potencial para a análise de HCT em águas. No entanto, o LOD obtido pode ainda não ser suficiente para uma aplicação direta em águas ambientais, sobretudo em situações de contaminação reduzida.
Hydrochlorothiazide (HCT) is a diuretic that is widely used to treat high blood pressure and fluid retention. Its presence has been detected in environmental water samples, including Wastewater Treatment Plants (WWTPs) effluents. WWTPs are not able to effectively eliminate the drugs present in the effluent, so they are discharged into surface waters. The European Union has recently adopted a directive that requires HCT to be removed by WWTP with a minimum efficiency of 80% relative to its influent load in municipal wastewater. Therefore, new methods for rapid, inexpensive, and portable monitoring are essential. In this work, an electrochemical sensor based on a molecularly printed polymer (MIP) was developed for the analysis of HCT, using an inkjet-printed paper electrode as the electrochemical cell. Subsequently, the working electrode was modified with carbon ink and graphene oxide (GO). The MIP sensor was fabricated by electropolymerization of the functional monomer 4- aminobenzoic acid in the presence of HCT. GO was found to be an efficient nanomaterial for enhancing the electrochemical signal of HCT. The MIP sensor exhibited a good linear relationship between HCT concentration and the oxidation peak current intensity, with limits of detection (LOD) and quantitation of 1.8 μmol L-1 and 5.7 μmol L-1, respectively. The developed MIP sensor shows potential for analyzing HCT in water. However, the obtained LOD may still not be sufficient for direct application in environmental waters, particularly in situations of low-level contamination.
Hydrochlorothiazide (HCT) is a diuretic that is widely used to treat high blood pressure and fluid retention. Its presence has been detected in environmental water samples, including Wastewater Treatment Plants (WWTPs) effluents. WWTPs are not able to effectively eliminate the drugs present in the effluent, so they are discharged into surface waters. The European Union has recently adopted a directive that requires HCT to be removed by WWTP with a minimum efficiency of 80% relative to its influent load in municipal wastewater. Therefore, new methods for rapid, inexpensive, and portable monitoring are essential. In this work, an electrochemical sensor based on a molecularly printed polymer (MIP) was developed for the analysis of HCT, using an inkjet-printed paper electrode as the electrochemical cell. Subsequently, the working electrode was modified with carbon ink and graphene oxide (GO). The MIP sensor was fabricated by electropolymerization of the functional monomer 4- aminobenzoic acid in the presence of HCT. GO was found to be an efficient nanomaterial for enhancing the electrochemical signal of HCT. The MIP sensor exhibited a good linear relationship between HCT concentration and the oxidation peak current intensity, with limits of detection (LOD) and quantitation of 1.8 μmol L-1 and 5.7 μmol L-1, respectively. The developed MIP sensor shows potential for analyzing HCT in water. However, the obtained LOD may still not be sufficient for direct application in environmental waters, particularly in situations of low-level contamination.
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Keywords
Electrochemical sensors molecularly imprinted polymers paper electrodes electropolymerisation graphene hydrochlorothiazide Sensores eletroquímicos Polímeros molecularmente impressos Elétrodos de papel Eletropolimerização Grafeno Hidroclorotiazida