MOF‐235 is presented as an orange powder, with crystals of the octahedral formation. It was already used as adsorbent to remove different compounds from water; however, no attempts have been published about the exploration of the MOF‐235 application as electrochemical sensor for organic compounds yet. MOF‐235 was synthetized and after that, it was characterized by SEM, XRD and FTIR. Graphite electrodes (GEs) were modified with different MOF‐235 ratio (5 %, 7 %, 10 %, 12 % and 14 %) and these modified GEs were characterized by cyclic voltammetry (CV) measurements in order to determine the effect of MOF‐235 concentration on the current response. Results indicated that, a significant improvement on the current response was attained at MOF‐235(10 %)/GE respect to unmodified GE. This behavior is related to the pore structure and multiple active sites on the MOF surface. The performance of the MOF‐235(10 %)/GE as electrochemical sensor for detecting catechol was assessed by differential pulse voltammetry (DPV). Catechol detection response of MOF‐based sensor provided a detection limit of about 12.79 μmol L−1 with a correlation coefficient (R2) of about 0.9928 ranging from 12 to 514 μmol L−1. Finally, MOF‐235(10 %)/GE was used to determine catechol in real water matrixes.
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In this work, a novel carbon paste electrode was modified with metal-organic framework (MOF) 235 for detecting lead ions in aqueous solutions using anodic redissolution voltammetry as analytical technique. Experimental parameters such as, amount of MOF-235, type of supporting electrolyte, potential and time deposition were evaluated to optimize the detection approach. The Pb 2+ detection response of this MOF-modified electrode allowed to achieve a detection limit of about 18 μg L-1 with a correlation coefficient (R²) of about 0.9962, extending in a linear concentration range from 50 to 300 μg L-1. Drinking water samples (as-received or spiked with well-known lead concentration) were analyzed to determine the concentration of lead ions. Data were also confirmed by Atomic Absorption Spectroscopy (AAS). Furthermore, the electrochemical determination when compared with the AAS, has shown that the electroanalytical approach represents a fast and quite reliable alternative for monitoring heavy metals.
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