Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: Aplicação em águas de chuva de regiões de Santa Catarina

Abstract

Neste estudo foi desenvolvida uma metodologia analítica para determinação de 2,4-dinitrofenol (2,4-DNP) em amostras de águas de chuva de regiões de Santa Catarina utilizando a voltametria de onda quadrada (VOQ) e de forma ex situ. O estudo envolveu a aplicabilidade de utilizar o eletrodo de carbono vítreo modificado com filme de bismuto. A formação do filme de bismuto foi otimizada por voltametria cíclica e em seguida, estudos de pH e eletrólito de suporte foram investigados para a redução do 2,4-DNP. Os parâmetros analíticos que afetam a sensibilidade da VOQ foram otimizados. Na sequência, as figuras analíticas de mérito foram obtidas: faixa linear de trabalho de 3,2 x 10-7 – 4,6 x 10-6 mol L-1, coeficiente de correlação de 0,996, RSD% = 17,5 (1,3 x 10-6 mol L-1, n = 6), 11,7 (2,5 x 10-6 mol L-1, n = 6) e 6,4 ( 4,5 x 10-6 mol L-1, n = 6), limite de detecção de 1,2 x 10-7 mol L-1. E, finalmente estudos de recuperação foram realizados para avaliar a exatidão da metodologia. Valores obtidos ficaram entre 84-112% (2,5 x 10-6 mol L-1) e 89 – 113% (4,5 x 10-6 mol L-1).

Voltammetric Quantification of 4-Nitrophenol Using a Multivariate Optimized Plated Bismuth Film Electrode

“…Figure presents the negative scans for 10 mg L –1 NP at 0.100 V s –1 in BRBS at the following pH: 3, 5, 7, and 9. As already reported, better signals are obtained at acid pH, in agreement with the proposed mechanism. − Particularly in this case as demonstrated by Figure , a well-defined current peak is obtained for pH values lower than 7 and the maximum reduction current peak is defined at pH 5. For alkaline solutions (pH 9), the signal is much lower and even two different peaks can be detected, indicating that different processes are taking place.…”

“…Nitrophenol (NP) determination can be electrochemically carried out by the reduction of the nitro group that proceeds by the following two-step mechanism: − Here, NP determination was evaluated by CV and SWV; in both cases, a negative current peak was observed. Optimization procedures were carried through to BiFE preparation deposited by CV, and for SWV parameters for nitrophenol determination, in both cases NP concentration was 10 mg L –1 .…”

“…Different industries, for instance, explosives, pharmaceuticals, and pesticides, use aromatic nitro compounds and some of them can be toxic or harmful to humans or the environment. In the particular cases of organic compounds determination, nitrophenol (NP) is selected as a test analyte because it has a reducible group that allows good evaluation of this type of film. ,,− In the ex situ BiFE deposition, different conditions ,,− ,,,,− have been proposed, starting with the media pH, which can be either acidic or acetate buffer with pH values between 4 and 5; furthermore, deposition potential is varied between −0.500 and −1.400 V, deposition time between 60 and 600 s, and Bi­(III) concentration from 2.5 × 10 –4 mol L –1 (100 ppm) to 2.0 × 10 –6 mol L –1 (900 ppb). Some authors claim that they have optimized the deposition method; however, to the best of our knowledge, the experimental parameters that influence the ex situ bismuth film electrodes obtained for nitrophenol current peak determination have been limited to single factor analysis. ,− No published research studies about multifactor interaction effects of Bi­(III) concentration, time, and deposition potential have been reported till now.…”

Κατασκευἠ Και Εφαρμογές Απορριπτόμενων Αισθητήρων Για Τον Ηλεκτροχημικό Προσδιορισμό Οργανικών Ενώσεων

“…ηλεκτροκαταλυτική δράση, κάτι που έχει ήδη αναφερθεί και βιβλιογραφικά74,94 . Τα τροποποιημένα με οξείδιο του βισμουθίου (4% w/w) εκτυπωμένα ηλεκτρόδια είναι αυτά που παρουσιάζουν τις υψηλότερες κορυφές αναγωγής και για τις τρείς νιτροφαινόλες και αυτά που επιλέχτηκαν για τον περαιτέρω προσδιορισμό αυτών των ενώσεων.…”

“…Με αύξηση της τιμής του pH στα βολταμμογραφήματα παρατηρήθηκε μετατόπιση της κορυφής ρεύματος σε πιο αρνητικές τιμές δυναμικού. Βασιζόμενοι σε αυτή τη μελέτη, οι τιμές pH που επιλέχθηκαν για τον προσδιορισμό των 3 νιτροφαινόλων ήταν το 6 για την 2-νιτροφαινόλη και την 4-νιτροφαινολη και το 4 για την 2,4-δινιτροφαινόλη, τιμές οι οποίες συμφωνούν και με την υπάρχουσα βιβλιογραφία94 .…”