Sensitive and rapid detection of pesticides in food has become an important and crucial research area due to the extensive use of agriculture residues and stringent environmental protection acts. In present work, an electrochemical nanohybrid sensor was facilely developed based on carboxymethyl cellulose (CMC) fuctionalized carbon nanotubes (CNTs). The sensor shows high sensitivity, excellent stability and good anti-interference capability in the detection of carbendazim (MBC) by differential pulse voltammetry method. Under optimized conditions, it exhibits a wide linearity of 0.03 μmol·L⁻¹ – 10 μmol·L⁻¹ with a low detection limit of 0.015 μmol·L⁻¹. In real samples analyses for peer and kiwifruit, the proposed sensor shows good recoveries which are comparable with that of the conventional HPLC method. In addition, the oxidation mechanism of MBC at the nanohybrid sensor was studied using voltammetric methods and validated according to the density functional theory (DFT) calculation. The results reveal that the oxidation of carbendazim is a typical adsorption-controlled electrochemical oxidation process proceeding with four protons and four electrons. The proposed nanohybrid sensor is a promising alternative to the currently used methods for carbendazim detection and our results provide a new insight in MBC electrochemical oxidation mechanism.

The essential oil extracted from Cinnamomum camphora leaves is a mixture of volatile compounds, mainly terpenes, and is widely used in medicine, perfume and chemical industries. In this study, the extraction processes of essential oil from Cinnamomum camphora leaves by steam distillation and supercritical CO₂ extraction were summarized and compared, and the camphor tree essential oil was detected by GC/MS. The extraction rate of essential oil extracted by steam distillation is less than 0.5%, while that of supercritical CO₂ extraction is 4.63% at 25 MPa, 45 °C and 2.5 h. GC/MS identified 21 and 42 compounds, respectively. The content of alcohols in the essential oil is more than 35%, and that of terpenoids is more than 80%. The steam extraction method can extract volatile substances with a low boiling point and more esters and epoxides; The supercritical method is suitable for extracting weak polar substances with a high alcohol content. Supercritical CO₂ extraction can selectively extract essential oil components and effectively prevent oxidation and the escape of heat sensitive substances.

Carbendazim, a very common contamination to the traditional Chinese medicines (TCMs), has posed serious threat to the environment and human health. However, sensitive and selective detection of carbendazim (MBC) in the TCMs is a big challenge for their complex chemical constituents. In this work, a 0D/1D nanohybrid was developed by anchoring 1T-phased MoS₂ quantum dots (QDs) over multiwall carbon nanotubes (MWCNTs) via a facile assembly method. High-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis (TGA) together with EIS reveal that the 1T-phased QDs can anchor over MWCNTs via van der Waals forces, and the anchoring improves the nanohybrid surface area and conductivity. Therefore, the electrochemical sensor fabricated based on the MoS₂ [email protected] nanohybrid shows excellent catalytic activity to MBC oxidation. Under optimized conditions, the sensor presents a linear voltammetry response to MBC concentration from 0.04 to 1.00 μmol·L^–1, a low detection limit of 2.6 × 10^–8 mol·L^–1, as well as high selectivity, good reproducibility, and long-term stability. Moreover, the sensor has been successfully employed to determine MBC in two typical TCMs and the obtained recoveries are in good accordance with the results achieved by HPLC, showing that the constructed sensor plate holds great practical application in MBC analysis with complex matrix.