**7. Advanced techniques for detection of carbamate pesticides**

In pesticide analysis, advanced technologies are presented as an alternative to the conventional chromatographic methods combined with selective sensors. The chromatographic procedures yielded sensitive, specific, and dependable analytical findings. However, they are time-consuming, complicated, and costly, with a high organic solvent usage, which is unsuitable for analyzing large samples [102]. New approaches are challenging to implement in most developing countries. The advancement of improved methodologies has resulted in promising instruments for easy and fast operation, affordable cost, and suitable for in-situ evaluation. Furthermore, they perform well in terms of pesticide detection accuracy and precision.

#### **7.1 Molecular imprinted polymer (MIP) biosensor**

Biosensors based on molecularly imprinted polymers (MIP) are widely used as sensitive sensing materials because they detect molecules with many biological weights. MIP has effectively created artificial materials that behave similarly to biological receptors; however, it has limited stability. MIP has also been indicated as a biosensing breakthrough due to its ability to overcome the drawbacks of current specific molecular elements such as antibodies, peptides, and enzymes [103]. MIP is used to detect pesticides by imitating biological receptors, polymerizing a functional monomer in the analyte, and finally removing the template using a polymer matrix [104]. Hence, this approach can detect pesticide residues in food since they are inexpensive, simple to use, and have excellent chemical and physical stability. Recently, Li et al. [105] published a work that demonstrated the construction of a MIPs biosensor to detect pesticides utilizing a carbon paste electrode modified with surface MIP microspheres and evaluated using cyclic voltammetry. The approach used on vegetable samples showed high sensitivity, with significant recoveries ranging from 97.2 to 101%. Additionally, Wang et al. [106] used a MIP sensor modified with polyquercetin(Qu)-polyresorcinol(Re)-AuNPs to assess methyl parathion in waters, juice drinks, and vegetable juice. Nevertheless, the analytical performance of sensors created to detect methyl parathion was lower. Xie et al. [107] detected pesticides in brown rice using MIP sensors and linear sweep voltammetry. Additionally, the MIPs sensor was produced via free-radical polymerization of p-vinylbenzoic acid on the surface of a modified glassy carbon electrode. The study demonstrated that the approach could detect thiamethoxam residues with an 88.7–94.0% recovery range. Li et al. [108] used differential pulse voltammetry to build a MIP-based sensor to analyze paraoxon and exhibited excellent stability after 3 months.

*Extraction and Identification Techniques for Quantification of Carbamate Pesticides in Fruits… DOI: http://dx.doi.org/10.5772/intechopen.102352*

#### **7.2 Optical biosensors**

Optical biosensors have attracted considerable interest and are being applied in various fields, including food safety and security, biological sciences, environmental sensing, and medical science. The optical characteristics of the optical transducers, including absorption, reflectance, and fluorescence emission, will change in response to the analyte. In many instances, optical biosensors have been used to detect pesticides, especially enzyme-based biomolecules Yotova and Medhat [109] developed an optical biosensor to identify pesticides contaminants based on the parallel immobilization of AChE and choline oxidase enzymes in silicon dioxide hybrid membranes. The bioactive component of the sensor is a multi-enzyme system that includes AChE and choline oxidase covalently immobilized on new hybrid membranes. It demonstrates a constant value of acetylcholine at concentrations ranging from 2.5 to 30 mM. Previously, Xavier et al. [110] studied an optical fiber biosensor for assessing propoxur and carbaryl in vegetable crops, employing chlorophenol red as an optical transducer of the analyte's inhibitory impact on the AChE enzyme. The linear dynamic ranges of carbaryl and propoxur are 0.8–3.0 mg L−1 and 0.03–0.50 mg L−1, respectively. However, propoxur has a lower detection limit (0.4 ng) than carbaryl in the biosensor (25 ng). Ultrasonic extraction was utilized to detect propoxur in spiked onion and lettuce, with recovery rates ranging from 93 to 95% for onion samples at the different concentration levels studied.

#### **7.3 Electrochemical biosensor**

Electrochemical biosensors are gaining traction as a novel detection principle, increasing sensitivity, specificity, and repeatability [111]. Biosensors, in theory, are made up of two or three-electrode systems, comprising auxiliary, reference, and working electrodes, that create electrical signals when a target biomolecule interacts with a recognition element [112, 113]. For example, Chauhan and Pundir [114] used iron oxide nanoparticles and carboxylated multi-walled carbon nanotubes nanocomposite-based AChE enzymes. The enzyme AChE was isolated from maize seedlings and covalently attached to a modified gold electrode as a working electrode. The modified gold electrode was developed to measure the presence of different pesticides, including malathion, chlorpyrifos, monocrotophos, and endosulfan in water and milk samples with LODs as low as 0.1 nmol L−1.

Similarly, Zhao et al. [84] established direct electrodeposition of electrochemically based reduced graphene oxide-gold nanoparticles-cyclodextrin and Prussian blue-Chitosan modified glass carbon electrodes for pesticide determination. The AChE enzyme was immobilized via adsorption with a low detection limit for carbaryl. An AChE enzyme-based biosensor based on rGO-coated GCE was also created to detect carbamate herbicides in tomatoes with a detection limit of 1.9 nmol L−1 [115]. Additionally, Sun et al. [116] have created an amperometric AChE biosensor-based poly (diallyldimethyl-ammonium chloride)-multi-walled carbon nanotubesgraphene hybrid film to evaluate carbaryl in vegetables. Besides, Cesarino et al. [117] used polyaniline and multi-walled carbon nanotubes core-shell modified glassy carbon electrode to construct electrochemical AChE biosensors to measure carbamate pesticides in apple, broccoli, and cabbage. The detection limits for carbaryl and methomyl were 1.4 and 0.95 mol L−1, which shows lower than the allowed concentrations indicated by Brazilian regulatory regulations for the pesticides tested in the samples. Besides that, Song et al. [118] detected the carbamate pesticides using citrate-capped gold nanoparticles. The biosensor was made by first creating 3D MPS

networks on an Au electrode and then adding citrate-capped AuNPs via an Au**–**S bond. Based on the inhibitory effect of carbamate insecticides on AChE activity, the pesticide's action may be evaluated at a shallow potential. It was also demonstrated that the method could detect carbamate pesticides in real-world samples.
