Voltammetric detection of carbofuran determination using screen-printed carbon electrodes modified with gold nanoparticles and graphene oxide.

Carbofuran is a highly toxic pesticide that is heavily used in agriculture due to its high effectiveness and low cost. Improved methods that are simpler and lower cost are needed for carbofuran detection in food and agricultural samples. Herein, we describe the development of a unique electrochemical method for carbofuran-phenol, which is the main hydrolysis product of carbofuran. We have successfully developed a highly accurate and precise method in a portable size using a screen-printed carbon electrode (SPCE) that is modified with graphene oxide (GO) and gold nanoparticles (AuNPs). Consequently, the developed electrode is highly sensitive to and selective for carbofuran. Using the central composite design (CCD) approach, we optimized the method for analysis parameters including the electrode surface loadings of GO and AuNPs as well as the working solution pH. The method exhibited a wide linear range of 1-250µM for analyte detection using differential pulse voltammetry (DPV) on AuNPs/GO-SPCE under the optimized conditions. The limits of detection and quantitation were 0.22 and 0.72µM, respectively. In addition, we also report the application of the method for carbofuran determination in real cucumber and rice samples. This sensitive and selective carbofuran detection method is very promising for simple and low cost analysis in real agricultural fields.

New furoquinoline alkaloids from the leaves of Evodia lepta.

Three new furoquinoline alkaloids, leptanoines A-C (1-3) along with three known compounds (4-6) were isolated from the leaves of Evodia lepta. Their structures were identified by interpretation of their spectroscopic data as well as comparison with those reported in the literature. In addition, all isolated compounds were evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities. Compound 4 showed the highest inhibitory activity towards BChE with an IC50 value of 47.9 µM. On the other hand, Compound 5 showed the highest inhibitory activity towards AChE with an IC50 value of 69.1 µM.