# Functionalized Carbon-Based Electrochemical Sensors for Food and Alcoholic Beverages Safety
## 3 Carbon Nanomaterial-Based Electrochemical Sensors
### CnTs
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Analytes** & **Materials** &
\begin{tabular}{c} **Electrochemical** \\ **Techniques** \\ \end{tabular} & **Linear Range** & **Detection Limit** & **Sample** & **Ref.** \\ \hline Dopamine & N-doped CDs & DPV & 0.05–8 μM & 1.2 nM & Serum & [67] \\ Dopamine & Au@CDs-CS & DPV and CV & 0.01–100 μM & 0.1 nM & Spiked sample & [68] \\ Triclosan & CNDs-chitosan & CV & 10 nM–1.0 mM & 9.2 nM & Water & [69] \\ H\({}_{2}\)O\({}_{2}\) & Hb-CNDs-chitosan & CV & 1–118 μM & 0.27 μM & Toothpaste & [70] \\ Uric acid & Fe@g-GD/N-CD & DPV & 5–120 μM & 0.08 μM & Urine & [71] \\ Cu\({}^{2+}\) ions & CDs-TPEA & DPASV & 1–60 μM & 100 μM & Spiked sample & [72] \\ Glucose & CDs/Cu\({}_{2}\)O NPs & CV & 0.02–4.3 mM & 8.4 μM & - & [64] \\ Acetantenophen & Fe-S-Au/CDs & CV & 0.5–46 μM & 0.1 μM & Urine & [74] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Typical applications of electrochemical sensors based on CD materials associated with electrochemical techniques for the detection of different target analytes. and EIS methods based on Fe\({}_{3}\)O\({}_{4}\)/modified carbon paste electrode (MCPE) in a three-electrode system. In their work, the incorporation of Fe\({}_{3}\)O\({}_{4}\)/MCPE electrodes as a sensor showed excellent sensitivity, selectivity, repeatability, reproducibility, stability, and low preparation cost via optimizing scan rates and pH values. The detection limits equating to 2.2-10 \(\upmu\)M for sinapic acid, 2.6-10 \(\upmu\)M for syringic acid, and 0.8-10 \(\upmu\)M for ruin were obtained. [86] Moreover, various types of metal nanoparticles were added onto the CNTs to generate additional electrocatalytic sites and to increase the sensitivity and detection limits of resultant electrodes [87]. A CS nanocomposite with Au-NP-decorated CNTs has been developed as an electrochemical sensor for the detection of catechol. Due to highly electrochemical active AuNPs, the excellent reproducibility and repeatability of catechol detection in the range of 0 to 1 mM were obtained by CV analysis, with a detection limit of 3.7 \(\upmu\)M [88]. [PERSON] et al. [89] reported Pt/MnO\({}_{2}\)/functionalized multi-wall CNT (f-MWCNT) electrode material was synthesized by a simple and facile strategy. As shown in Figure 4b, the as-prepared Pt/MnO\({}_{2}\)/f-MWCNT, having a larger effective surface area, greater porosity, and more reactive sites than bare MWCNTs, exhibited excellent sensitivity for catechin sensing. Under optimized conditions, a very low detection limit (0.02 \(\upmu\)M) and the linear range of 2-950 \(\upmu\)M were obtained. The developed electrochemical sensor was expected to be useful for industrial applications because of the electrochemical reactivity, excellent reproducibility, and good long-term stability. Similarly, as shown in Figure 4c, a novel electrochemical sensor based on GOX-NFM/MWCNT composite was developed by electrospinning and coating methods to detect glucose in beer samples. The electrochemical response of the sensor was analyzed by CV and CA, and excellent reproducibility and repeatability to glucose detection in the range of 1-3 mM were found with a detection limit of 20 \(\upmu\)M [90].