Extraction of Camphor Tree Essential Oil by Steam Distillation and Supercritical CO2 Extraction.

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.

Anchoring Metallic MoS2 Quantum Dots over MWCNTs for Highly Sensitive Detection of Postharvest Fungicide in Traditional Chinese Medicines.

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 QDs@MWCNT 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.

Phosphorene nanocomposite with high environmental stability and antifouling capability for simultaneous sensing of clenbuterol and ractopamine.

A series of phosphorene (BP) nanocomposites was prepared to realize simultaneous electrochemical determination of clenbuterol (CLB) and ractopamine (RAC). CLB and RAC are the most commonly used ß-agonists in animal-derived food. The BP nanohybrid was obtained by co-decoration with both mono(6-mercapto-6-deoxy)-ß-cyclodextrin and poly(3,4-ethylenedioxythiophene) nanoparticles. It displays high stability, antifouling capability, a large electrochemical active surface and good electrochemical response. The electrochemical assisted antifouling strategy was selected by further eliminating the fouling of the electrode surface using continuous cyclic voltammetry. The electrode was employed for electrochemical sensing of CLB and RAC at typical peak voltages of 0.8 and 1.0 V (vs. SCE). Responses are linear in the 0.3-90 µM concentration range for CLB, and from 0.3 to 9.4 µM for RAC under optimal conditions. The limit of detection are 0.14 and 0.12 µM, respectively. The sensor was employed for simultaneous determination of CLB and RAC in (spiked) beef, feed and bovine serum samples with acceptable recoveries. Graphical abstractAn electrochemically assisted anti-fouling method for simultaneous voltammetric nanosensing of clenbuterol (CLB) and ractopamine (RAC) in edible cattle product samples using high-stable and anti-foul phosphorene (BP) co-decorated with mono(6-mercapto-6-deoxy)-ß-cyclodextrin (S-ß-CD) and poly(3,4-ethylenedioxythiophene) (PEDOTNPs).