Sensores voltamétricos baseados em eletrodos compósitos e carbono vítreo modificados com grafeno, nanotubos de carbono e partículas magnéticas e eletrodo de TiO2NT autodopado para a determinação de diuréticos em fluídos biológicos
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Data
2019-02-28
Autores
Hudari, Felipe Fantinato [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A aplicabilidade dos métodos analíticos na Química Forense tem como grande desafio a complexidade das matrizes biológicas (urina, fezes, suor, cabelos e pelos), o uso de técnicas com baixo limite de detecção, a avaliação de metabólitos gerados em baixa concentração após metabolização e a busca de técnicas e metodologias eficientes, porém de baixo custo. O objetivo do presente trabaho foi investigar novos métodos eletroanalíticos para determinação dos diuréticos bumetanida (BMT), hidroclorotiazida (HCT) e triantereno (TRT) em consonância com as diretrizes e controle da Agência Mundial Antidopagem. Sensores eletroquímicos foram desenvolvidos usando eletrodos compósitos, eletrodos de carbono vítreo e eletrodo de nanotubos de TiO2 tratados catodicamente modificados com partículas magnéticas, óxido de grafeno reduzido e nanotubos de carbono multiparedes para a determinação dos diuréticos BMT, HCT e TRT, proibidos pela Agência Mundial Antidoping (WADA). Para a determinação do diurético TRT foi desenvolvido um sensor baseado na modificação da superfície de um eletrodo compósito grafite-epoxy com partículas magnéticas funcionalizadas com grupo tosil. Após otimização multivariada dos parâmentros inerentes à técnica de voltametria de onda quadrada, uma curva de calibração foi construída no intervalo de 0,500 a 99,8 µmol L−1 com limite de detecção de 1,47×10−7 mol L−1. O sensor foi aplicado em amostra de urina e comparado com a técnica de LC-MS/MS onde não houve diferença significativa no nível de 95% de confiança entre os métodos. Já para a determinação do diurético BMT, um sensor baseado em eletrodo de carbono vítreo modificado com óxido de grafeno reduzido foi desenvolvido a partir da eletrodeposição de uma solução de 0,1 mg mL−1 de óxido de grafeno mantida em potencial de −1,4V por 500 s. Após otimização da velocidade de varredura (100 mV s−1), pH (4,0) e tempo de acúmulo (25 s), uma relação linear foi encontrada no intervalo de 0,25 a 50 μmol L−1 de BMT, onde foi encontrado um limite de detecção de 75 nmol L−1. O método foi aplicado em amostra de urina e comparado ao método de LC-MS/MS, onde não houve diferença significativa ao nível de 95% de confinaça entre os métodos. Outro sensor baseado em eletrodo de carbono vítreo modificado com nanotubo de carbonos foi proposto para a determinação de HCT e TRT. Após otimização dos parâmetros como pH (4,0), Eac (0,80 V) e tac (40 s) e utilizando a técnica de varredura linear de redissolução adsortiva (LSAdSV), foi construída uma curva de calibração entre 1,0×10−7 a 2,0×10−5 mol L−1 para ambos, HCT e TRT, onde foram encontrados os valores de 2,8×10−8 e 2,9×10−8 mol L−1 para os limites de detecção da HCT e TRT, respectivamente. O método proposto foi aplicado eficientemente em amostra de urina sintética. Todos os sensores supracitados apresentaram limites de detecção e quantificação inferiores ao estipulado pela WADA (250 ng mL−1). Foi ainda desenvolvida uma nova plataforma sensorial baseada em eletrodo de nanotubos de TiO2 autodopados com Ti+3, via redução eletroquímica em potencial de −2,5V. O semicondutor mostrou-se apto a monitorar a oxidação eletroquímica do diurético TRT. Curvas analíticas foram construídas no intervalo de 2 a 100 µmol L−1 e um valor de limite de detecção de 5,40×10−7 foi encontrado utilizando a técnica de voltametria de varredura linear.
The applicability of the analytical methods in Forensic Chemistry has as a great challenge the complexity of the biological matrices (urine, feces, sweat, hair and hair), the use of techniques with low limit of detection, the evaluation of metabolites generated in low concentration after metabolism and the search for efficient but cost-effective techniques and methodologies. The objective of the present study was to investigate new electroanalytical methods for the determination of diuretics bumetanide (BMT), hydrochlorothiazide (HCT) and trianterene (TRT) in accordance with the guidelines and control of the World Anti-Doping Agency. Electrochemical sensors were developed using composite electrodes, glassy carbon electrodes and self-doping TiO2 nanotube electrodes modified with magnetic particles, reduced graphene oxide and carbon nanotubes for the determination of the diuretics BMT, HCT and TRT banned by the World Anti-Doping Agency (WADA). For the determination of the diuretic TRT, a sensor based on the modification of the surface of a composite graphite-epoxy electrode with magnetic particles functionalized with tosyl group was developed. After a multivariate optimization of the parameters inherent to the square wave voltammetry technique, a calibration curve was constructed in the range of 0.500 to 99.8 μmol L−1 with a detection limit of 1.47×10−7 mol L−1. The sensor was applied in a urine sample and compared to the LC-MS/MS technique where there was no significant difference at the 95% level of confidence between the methods. For the determination of the diuretic BMT, a sensor based on glassy carbon electrode modified with reduced graphene oxide was developed from the electrodeposition of a solution of 0.1 mg mL−1 of graphene oxide maintained at −1, 4V for 500 s. After optimization of the scan rate (100 mV s−1), pH (4.0) and accumulation time (25 s), a linear relationship was found in the range of 0.26 to 50 μmol L−1 of BMT, where a detection limit of 75 nmol L−1 was found. The method was applied in a urine sample and compared to the LC-MS / MS method, where there was no significant difference at the 95% level of confinement between the methods. Another sensor based on carbon nanotube modified glassy carbon electrode was proposed for the determination of HCT and TRT. After optimization of the parameters such as pH (4.0), Eac (0.80 V) and tac (40 s) and using the linear adsorptive redissolution (LSAdSV) technique, a calibration curve was constructed between 1.0×10−7 to 2.0×10−5 mol L−1 for both HCT and TRT, where values of 2.8×10−8 and 2.9×10−8 mol L−1 for the detection limits of HCT and TRT, respectively. The proposed method was applied efficiently in a synthetic urine sample. All of the aforementioned sensors had limits of detection and quantification lower than that stipulated by the WADA (250 ng mL−1). It was also developed a new sensory platform of electrodes of TiO2 nanotubes autopados with Ti+3, via electrochemical reduction in potential of −2.5V. The semiconductor was able to monitor the electrochemical oxidation of the diuretic TRT. Analytical curves were constructed in the range of 2 to 100 μmol L−1 and a detection limit value of 5.40×10−7 was found using linear sweep voltammetry technique.
The applicability of the analytical methods in Forensic Chemistry has as a great challenge the complexity of the biological matrices (urine, feces, sweat, hair and hair), the use of techniques with low limit of detection, the evaluation of metabolites generated in low concentration after metabolism and the search for efficient but cost-effective techniques and methodologies. The objective of the present study was to investigate new electroanalytical methods for the determination of diuretics bumetanide (BMT), hydrochlorothiazide (HCT) and trianterene (TRT) in accordance with the guidelines and control of the World Anti-Doping Agency. Electrochemical sensors were developed using composite electrodes, glassy carbon electrodes and self-doping TiO2 nanotube electrodes modified with magnetic particles, reduced graphene oxide and carbon nanotubes for the determination of the diuretics BMT, HCT and TRT banned by the World Anti-Doping Agency (WADA). For the determination of the diuretic TRT, a sensor based on the modification of the surface of a composite graphite-epoxy electrode with magnetic particles functionalized with tosyl group was developed. After a multivariate optimization of the parameters inherent to the square wave voltammetry technique, a calibration curve was constructed in the range of 0.500 to 99.8 μmol L−1 with a detection limit of 1.47×10−7 mol L−1. The sensor was applied in a urine sample and compared to the LC-MS/MS technique where there was no significant difference at the 95% level of confidence between the methods. For the determination of the diuretic BMT, a sensor based on glassy carbon electrode modified with reduced graphene oxide was developed from the electrodeposition of a solution of 0.1 mg mL−1 of graphene oxide maintained at −1, 4V for 500 s. After optimization of the scan rate (100 mV s−1), pH (4.0) and accumulation time (25 s), a linear relationship was found in the range of 0.26 to 50 μmol L−1 of BMT, where a detection limit of 75 nmol L−1 was found. The method was applied in a urine sample and compared to the LC-MS / MS method, where there was no significant difference at the 95% level of confinement between the methods. Another sensor based on carbon nanotube modified glassy carbon electrode was proposed for the determination of HCT and TRT. After optimization of the parameters such as pH (4.0), Eac (0.80 V) and tac (40 s) and using the linear adsorptive redissolution (LSAdSV) technique, a calibration curve was constructed between 1.0×10−7 to 2.0×10−5 mol L−1 for both HCT and TRT, where values of 2.8×10−8 and 2.9×10−8 mol L−1 for the detection limits of HCT and TRT, respectively. The proposed method was applied efficiently in a synthetic urine sample. All of the aforementioned sensors had limits of detection and quantification lower than that stipulated by the WADA (250 ng mL−1). It was also developed a new sensory platform of electrodes of TiO2 nanotubes autopados with Ti+3, via electrochemical reduction in potential of −2.5V. The semiconductor was able to monitor the electrochemical oxidation of the diuretic TRT. Analytical curves were constructed in the range of 2 to 100 μmol L−1 and a detection limit value of 5.40×10−7 was found using linear sweep voltammetry technique.
Descrição
Palavras-chave
Sensores eletroquímicos, Análise de diuréticos, Métodos eletroanalíticos, Triantereno, Hidroclorotiazida, Bumetamida