Abstract
Excessive nitrite amounts harm the environment and put public health at high risk. Therefore, accurate and sensitive detection of nitrite in surface and groundwater is mandatory for mitigating its adverse effects. Herein, a highly sensitive electrochemical sensor based on carbon screen-printed electrodes (CSPE) surface-modified with photochemically-made gold nanoparticles (AuNPs, ~12 nm) is proposed for nitrite detection. Scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy show that AuNPs uniformly coat the CSPE, increase its surface area, and contribute to oxidizing nitrite to much lower potential (+0.5 V vs. Ag/AgCl) and faster rate. Under optimized differential pulse voltammetry conditions, the CSPE/AuNPs-PEI electrode responds linearly (R2 > 0.99) to nitrite within a wide concentration range (0.01–4.0 µM), showing a sensitivity of 0.85 µA·µM−1·cm−2 and limit of detection as low as 2.5 nM. The CSPE/AuNPs-PEI electrode successfully detects nitrite in tap water and canned water of olives, showing no influence of those matrices. In addition, the electrode’s response is highly reproducible since a relative standard deviation lower than 10% is observed when the same electrode is operated in five consecutive measurements or when electrodes of different fabrication batches are evaluated.
Highlights
The excessive use of chemical fertilizers, the heavy use of pesticides in farming and industrial activities, and household waste have resulted in high levels of pollutants in the environment
This study reports about the use of AuNPs, produced by an ecofriendly photochemical route, to modify commercially available carbon screen-printed electrodes (CSPE) and use them on the sensitive detection of nitrite
Thisstudy studydemonstrates demonstrates photochemically-synthesized nanoparticles. This thatthat photochemically-synthesized goldgold nanoparticles coated coated with poly(ethyleneimine) provide a strong electrocatalytic effect for commercially with poly(ethyleneimine) provide a strong electrocatalytic effect for commercially available available carbon screen-printed electrodes toward nitrite oxidation
Summary
The excessive use of chemical fertilizers, the heavy use of pesticides in farming and industrial activities, and household waste have resulted in high levels of pollutants in the environment. The excess intake of nitrite can accelerate the irreversible oxidation reaction of hemoglobin to methemoglobin, limiting the ability of hemoglobin to carry oxygen [4]. Nitrite may react with amines to form nitrosamines, which are toxic and carcinogenic [5]. For these reasons, the allowable limit of nitrite concentration in drinking water is 43.48 μM, according to the World Health
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