Ag-CeO2 Based on Electrochemical Sensor for High-Efficient On-Site Detection of Nitrite in Aquaculture Water and Beverages

Abstract

Nitrite is one of the most common nitrogenous compounds, which is not only an important indicator of aquaculture water but also widely used as a food additive. Its potential toxicity poses a huge threat to aquatic products and human health. Therefore, it is important to develop a convenient and rapid sensor for the high-efficient onsite detection of nitrite. In this work, a novel electrochemical sensor was developed for the qualitative and quantitative analysis of nitrite. The developed nitrite electrochemical detection system is easily applied in onsite detection. The electrochemical working electrode was constructed based on the combination of Ag-CeO₂ and conductive carbon paste (CPE) with excellent electrocatalysis activity and rapid electron transfer ability. By the application of the developed system and under the optimal conditions, the linear range was from 40.0 μM to 500.0 μM, and the detection limit was reduced to 4.3 μM. The recovery was between 92.1% and 108.1%, and the relative standard deviations (RSDs) were 0.49%~9.31%. The sensor exhibited superior reproducibility, high stability sensitivity, and anti-interference ability, confirming its effectiveness for nitrite analysis. Finally, the developed electrochemical sensor was successfully applied to detect nitrite in beverages and aquaculture water samples, indicating that this approach has great potential in onsite food testing and environmental monitoring.

Keywords: Ag-CeO2; aquaculture water; beverage testing; electrochemical sensor; nitrite.

Figure 1

Ag-CeO₂ electrochemical sensor for the detection of nitrite.

Figure 2

(A) Low magnification TEM images of Ag-CeO₂. (B) High magnification TEM images of Ag-CeO₂. (C–E) Elemental analysis images of Ce, O, and Ag.

Figure 3

(A) XRD spectrum of CeO₂ and Ag-CeO₂. (B) Raman spectra of Ag−CeO₂.

Figure 4

(A) CVs of the CPE, Ag-CeO₂, CeO₂@C, and Ag-CeO₂@C in 5 mM K₃[Fe(CN)₆] and 0.1 M KCl at a scan rate of 100 mV s⁻¹. (B) EIS test. (C) CV test at different scanning speeds. (D) Linearity between the current and scan rate for ECSA testing.

Figure 5

(A) Scanning speed test. (B) Relationship between scanning speed and peak current. (C) Logarithm of scanning speed versus peak voltage.

Figure 6

(A) DPV test of Ag-CeO₂@C electrode in 100 μM NaNO₂ and 0.1 M PBS solutions at different pHs. (B) Linear relationship between pH and peak oxidation potential.

Figure 7

(A) Ag-CeO₂@C interference test at 0.1 M PBS, 100 μM NO₂⁻, and 50 times the concentration of other ions. (B) Linear relationship between NO₂⁻ concentration and peak oxidation current. (C) Fourteen days of continuous monitoring (bar graph shows the current intensity and broken line shows the ratio of the current intensity).