# Nitrite: From Application to Detection and Development
## 5 Electrochemical Sensors
As another example, ZrNPs/Fe\({}_{3}\)O\({}_{4}\)/GO nanocomposites have been prepared by in situ synthesis for the first time, and modified glassy carbon electrodes were prepared using the synthesized nanocomplexes as modifiers for the detection of nitrite ions in foods [112]. In addition, Au/Ni nanotubes were prepared on carbon paper by depositing Au nanoparticles on Ni nanotubes, and Au nanoparticles were uniformly distributed on Ni nanotubes. This has led to great improvement in the sensing performance of the sensor due to the synergistic effect of the two [113]. In addition, an electrochemical sensing platform based on acid-treated Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\) nanoparticles was used to detect nitrate and nitrite [114]. Scientists used \(\beta\)-cyclodextrinnin-modified gold nanoparticles (SH-\(\beta\)-CD@AuNPs) substrate, metal nanoparticles, and cyclodextrin supramolecular compounds to prepare a super-selective and Raman-active substrate. It can be used for the detection of nitrite and nitrate-nitrogen assays [115]. A polyaniline-linked tetra amino cobalt phthalocyanine surface functionalized ZnO hybrid nanomaterial (PA-TaCoPc@ZnO) for the sensitive electrochemical detection of nitrite is constantly moving toward achieving cost-effectiveness [116]. Similarly, nanocomposites of ZIF-8@ZIF-67/Au core-shell metal organic framework were easy to design and synthesize at low cost. The sensors made from them have the same advantages in detection that most nanomaterials possess [117]. Regarding the quantitative methods of electrochemical sensors, they can be mainly classified into potentiometry measurement, voltammetry measurement, impedance measurement, and other methods. Differential pulse voltammetry (DPV) and amperometry methods of GCE are usually used for the quantitative electrochemical analyses of trace level nitrite ions. Meanwhile related studies have investigated the inferred effect of various anions and cations on the oxidation peak current of nitrite by employing an amperometry method. A stable and reliable current response was obtained for the analysis of nitrite in water samples [118]. As another example, the electrochemical performance of a sensor developed using NPs was investigated using electrochemical methods to quantify nitrite [119]. In addition to this, the combination of electrochemical sensors and smart devices further improves detection efficiency. A combination of sensors, colorimetry, and smartphones detect nitrites using gold-covered graphene [120]. In short, electrochemical sensors in the detection of nitrite in the future direction of development may be (1) more sensitive, more selective [110], and combined with a variety of detection methods and new materials to achieve the rapid, accurate, and reliable detection of nitrite; (2) more and more miniaturized and portable, easy to carry, and able to adapt to a variety of complex environments and applications; (3) including a variety of functions [120], such as the simultaneous detection of multiple substances and real-time monitoring, to meet different needs; (4) more intelligent and able to judge and process data independently, improving detection efficiency and accuracy; and (5) more low-cost, reducing the cost [116] of use and promoting its application in a wider range of fields. \begin{table}
\begin{tabular}{l c c c} \hline \hline \multicolumn{1}{c}{**Nomenclature**} & \multicolumn{2}{c}{**Definitions and Explanations**} \\ \hline Nafion/Hb/AuNRs-WS\({}_{2}\)/CILE & \begin{tabular}{c} Nafion/Hb/AuNRs-WS\({}_{2}\)/CILE \\ \end{tabular} & \
\begin{tabular}{c} Nafion/Hb/AuNRs-WS\({}_{2}\)/CILE \\ \end{tabular} &
\begin{tabular}{c} Asfion, haemoglobin (Hb), gold nanorods—tungsten disulphide (AuNRs-WS\({}_{2}\)), and carbon fiber ionic liquid electrode (CILE) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Definitions and explanations corresponding to the abbreviations appearing in the Table 3.