Fast and simultaneous determination of Pb2+ and Cu2+ in water samples using a solid paraffin-based carbon paste electrode chemically modified with 2-aminothiazole-silica-gel

Abstract

Um eletrodo de pasta de carbono preparado com parafina sólida como aglutinante e quimicamente modificado com sílica funcionalizada com grupos 2-aminotiazol foi empregado na quantificação simultânea de Pb 2+ e Cu 2+ em amostras de água por meio de voltametria de redissolução anódica. O presente método emprega um tempo curto de pré-concentração (180 s), o qual permitiu a quantificação simultânea e confiável de Pb 2+ e Cu 2+ de maneira bastante rápida. Foram obtidos limites de detecção de 7,3 e 90 nmol L −1 para Pb 2+ e Cu 2+ , respectivamente. Estes valores estão abaixo das concentrações máximas permitidas destes metais em água potável segundo a legislação brasileira, indicando que o método proposto é aplicável para o monitoramento de Pb 2+ e Cu 2+ em amostras de água. Estudos de recuperação foram realizados em quatro amostras de água enriquecidas, sendo obtidas porcentagens de recuperação próximas a 100% para todas as amostras analisadas, demonstrando a boa acuracidade do método proposto.A solid paraffin-based carbon paste electrode modified with 2-aminothiazole functionalized silica-gel was used for simultaneous quantification of Pb 2+ and Cu 2+ in water samples by anodic stripping voltammetry. The present method uses short preconcentration time (180 s), which allowed reliable and simultaneous quantification of Pb 2+ and Cu 2+ in a very fast way. Detection limits of 7.3 and 90 nmol L −1 were obtained for Pb 2+ and Cu 2+ , respectively. These values are below their maximum concentrations allowed in drinking water by Brazilian legislation, indicating that the proposed method is useful to monitoring Pb 2+ and Cu 2+ in water samples. Recovery studies were performed in four spiked water samples and the results shown recovery percentages close to 100% for all analyzed samples, demonstrating the good accuracy of the proposed method.Keywords: anodic stripping voltammetry, carbon paste electrode, 2-aminothiazolefunctionalized silica gel, lead and copper determination, water samples IntroductionEnvironmental contamination by heavy metals is a growing concern because they are very toxic, bioaccumulative and totally non-degradable. Therefore, environmental monitoring of heavy metals is of great importance for many reasons, such as identification of pollutant sources, understanding pollutant dissemination, anticipation of remediation procedures, etc. Copper and lead are two very important metallic pollutants because they are toxic and abundant. Contamination of natural waters by anthropogenic activities is one of the main ways to introduce heavy metals in the environment. Therefore, quantification of metallic ions in water samples is very important in order to preserve safe water resources for world population. In all regions around the world, legislative instruments are very restrictive regarding copper and lead contents in water for human consumption. In Brazil, for example, limits for Pb 2+ and Cu 2+ in drinking water are 0.01 mg L −1 (48 nmol L −1 ) and 2 mg L −1 (31 μmol L −1 ) , respectively. 1 Graphite furnace ato...

Uncured Polydimethylsiloxane as Binder Agent for Carbon Paste Electrodes: Application to the Quantification of Propranolol

“…The narrowest potential window was found in 0.1 mol L -1 KOH, which is in close agreement with the previously reported for silicone-rubber CPEs. 35 The useful potential windows observed in the other supporting electrolytes were close to 1.5 V, and they are comparable with the potential window obtained with silicone-rubber 35 and solid-paraffin 8 CPEs. Nujol ® -CPE has presented narrower useful potential window and higher background currents regardless of the supporting electrolyte ( Figure S4, SI section).…”

“…A chemically modified CPE is obtained by the simple addition of the chemical modifier to the mixture between graphite powder and the binder agent. Several chemical modifiers have been used such as ion exchange materials, 6,7 silica, and organofunctionalized silicas, [8][9][10][11] metallic nanoparticles, 12,13 oxides 14 and complexes, 15,16 carbon nanotubes, 17 etc. These materials have allowed the preparation of CPEs with superior analytical performance extending their application to trace analysis of different kinds of analytes, such as metal ions, 18,19 drugs, 20,21 organic pollutants, 22 and biologically important compounds.…”

Simultaneous Voltammetric Determination of Zn(II), Pb(II), Cu(II), and Hg(II) in Ethanol Fuel Using an Organofunctionalized Modified Graphite‐Polyurethane Composite Disposable Screen‐Printed Device

“…The currents were measured in triplicate and their aver- age allowed obtaining the analytical curves for each metallic ion ( Figure 9B). The linear dynamic ranges, detection limits (three times the signal blank/slope) [39], and linear equations for the metal ions are presented in Table 2.…”

Desenvolvimento de eletrodos de pasta de carbono a base de polidimetilsiloxano aplicados para a quantificação de propranolol em formulações farmacêuticas

“…Os agentes modificadores à base de sílica são empregados frequentemente para modificação de CPEs aplicados na determinação de metais em diversas matrizes [55,[56][57]58].…”

“…Com estes resultados, é possível verificar que o eletrodo preparado com óleo mineral Nujol ® apresenta melhor resposta voltamétrica para oxidação de PROP, fornecendo pico voltamétrico mais intenso e definido em relação ao eletrodo preparado com parafina. A pasta preparada com parafina é mais compacta e rígida, além disso, apresenta maior hidrofobicidade em relação a pasta preparada com Nujol ® , dificultando o contato eletrodo-analito, resultando assim em um pico com baixa intensidade [55]. O bom desempenho de CPE preparados com óleo mineral Nujol ® para a análise e determinação de fármacos, especialmente os da classe de β-bloqueadores, é relatado em algumas publicações [35,42].…”