RESUMO
A glassy carbon electrode was modified with carbon black and CdTe quantum dots in a chitosan film to obtained a sensor for norfloxacin (NOR) in the presence of dopamine, caffeine, and uric acid. The morphological, structural and electrochemical characteristics of the nanostructured material were evaluated using spectrophotometry, X-ray diffraction, transmission electronic microscopy and voltammetry. The high electrochemical activity, fast electron transfer rate and high surface area enhanced the oxidation peak currents and shifted the peak potentials of NOR for more negative values (typically at 0.95 V vs. Ag/AgCl). Electrochemical determination of NOR was carried out using square-wave adsorptive anodic stripping voltammetry (SWAdASV). Response is linear in the 0.2 to 7.4 µmol L-1 NOR concentration range, and the detection limit is as low as 6.6 nmol L-1. The method was successfully applied to the determination of norfloxacin in pharmaceutical formulation, synthetic urine and spiked serum. Graphical abstract Schematic presentation of a voltammetric method using a glassy carbon electrode modified with carbon black and CdTe quantum dots in a chitosan film for the determination of norfloxacin in serum and urine samples.
Assuntos
Técnicas Eletroquímicas/métodos , Norfloxacino/análise , Pontos Quânticos/química , Compostos de Cádmio , Carbono/química , Quitosana , Eletrodos , Limite de Detecção , Norfloxacino/sangue , Norfloxacino/urina , TelúrioRESUMO
A glassy carbon electrode was modified with a TiO2-gold nanoparticle hybrid integrated with multi-walled carbon nanotubes in a dihexadecylphosphate film (TiO2-Au NP-MWCNT-DHP/GCE) and applied to amperometric determination of ascorbic acid (AA). The modified sensor displays fast charge transfer and shows an irreversible anodic behavior for AA by cyclic voltammetry. Under optimal experimental conditions and using amperometry at 0.4 V, the analytical curve presented a statistical linear concentration range for AA from 5.0 to 51 µmol L-1, with a limit of detection of 1.2 µmol L-1. The electrode was successfully applied to the determination of AA in pharmaceutical and fruit juice without the need for major pretreatment of samples. Graphical abstract Schematic of a new sensing platform for ascorbic acid (AA). It is based on a glassy carbon electrode (GCE) modified with TiO2-Au nanoparticles integrated into carbon nanotubes in a dihexadecylphosphate film. The sensor was applied to amperometric determination of AA in juice and pharmaceutical samples.
RESUMO
The use of water hyacinth's dried matter (Eichhornia crasippes) as a support matrix for nano-MnO2 and its application for the removal of indigo carmine RIC) was studied. Different pretreatment processes were tested and results indicated that an acid-alkali pretreatment is an efficient method to binding nanoparticles RNPs) to cellulosic matrix. In adittion, the MnO2 NPs were synthesized by sonochemical reduction of MnO4- using different methods Rultrasonic horn system, ultrasonic bath and reaction with ethanol), where the influence of the precursor concentration was observed. The synthesized material was further characterized by ATR-IR, AAS, XRD, SEM, nitrogen isotherms adsorption, EDS, and pHpzc. The IC removal capacity of the nanostructured material, the chemical nature of the degradation products and the effect of various parameters Rtemperature, pH, initial IC concentration, among others) were explored in water samples.
Se estudió el uso de la materia seca del jacinto de agua (Eichhornia crassipes) como matriz-soporte para nano-MnO2 y su eficiencia en la eliminación de índigo carmín RIC). Se ensayaron diferentes procesos de pretratamiento y los resultados indicaron que un tratamiento previo ácido-alcalino es un método eficiente para unir las nanopartículas (NPs) a la matriz celulósica. Así mismo, las NPs de MnO2 se sintetizaron por reducción sonoquímica de MnO4- utilizando diferentes métodos Run sistema emisor de ultrasonido, baño de ultrasonido y reacción convencional con etanol como medio). El material sintetizado se caracterizó por ATR-IR, AAS, DRX, SEM, isotermas de adsorción de nitrógeno, EDS y pHpzc. Se exploró la capacidad de eliminación de IC por parte del material nanoestructurado y la naturaleza química de los productos de degradación en muestras acuosas. Se analizó el efecto de diversos parámetros tales como temperatura, pH, concentración inicial de IC, entre otros.
Foi estudada a utilização de matéria seca de jacinto de água (Eichhornia crassipes) como matriz de suporte para nano-MnO2 e sua aplicação para a remoção de índigo carmine RIC). Diferentes processos de prétratamento foram testados e os resultados indicaram que o prétratamento ácido-álcali é um método eficiente para ligar os NPs à matriz celulósica. Além disso, as NPs de MnO2 foram sintetizados por redução sonoquímica de MnO4- utilizando diferentes métodos (um sistema emissor de ultrassom, banho de ultrassom e a reacção com o etanol). O material sintetizado foi caracterizado por ATR-IR, AAS, DRX, SEM, isotermas de adsorção de nitrogênio, EDS e pHpzc. A facilidade de remoção de IC por o material nanoestruturado e a natureza química da degradação dos produtos foram explorados em amostras aquosas, assim mesmo foi estudado o efeito de vários parâmetros Rtemperatura, pH, concentração inicial de IC e a quantidade de nanocompósito, entre outros).