Interfacial synthesis of a three-dimensional hierarchical MoS2-NS@Ag-NP nanocomposite as a SERS nanosensor for ultrasensitive thiram detection.

Interfacial self-assembly of ordered nanostructures at oil-water interfaces towards the fabrication of nanofilms has attracted the interest of plenty of scientists, since its discovery in 2004. Herein, further developments have been achieved, and we report a new strategy for the synthesis of a three-dimensional (3D) hierarchical nanostructure, through an interfacial synthesis driven microemulsion process. Thus, the synthesis route has been simplified, with the rigorous experimental conditions of traditional compositing technology. Combined with a two-step seed-mediated growth method for preparing uniform Ag-NPs, a plasmonic 3D MoS2-NS@Ag-NP nanostructure was successfully developed as a Surface-Enhanced Raman Scattering (SERS) active substrate, with plenty of surface hot spots, leading to an enhancement factor (EF) of 1.2 × 108 derived from both electromagnetic mechanism (EM) and chemical mechanism (CM) effects. The 3D MoS2-NS@Ag-NP nanostructure can be applied to detect trace thiram in apple juice and local lake water, with a detection limit as low as 10 ppb (42 nM), which is much lower than the maximal residue limit (MRL) of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA). Furthermore, quantitative analysis was achieved in the range of 10 ppb-1 ppm with good homogeneity and selectivity.

[Determination of trace elements in mylabris before and after being processed].

OBJECTIVE: To discuss the processing principle of Mylabris by comparing the differences between the contents of 11 trace elements in Mylabris before and after being processed. METHODS: Used Flame AAS, Graphite Furnace AAS and Hydride generation AAS to determine the content of Cu, Mn, Zn, Fe, Mg, Ca, K, Pb, Cd, As and Hg elements in Mylabris samples. RESULTS: The sequence of 11 trace elements contents in the Mylabris samples from high to low was: K > Mg > Fe > Ca > Zn > Mn > Cu > Pb > As > Hg > Cd. In Mylabris after being processed, the contents of Pb, As, Hg, Cd and Fe elements decreased, Cu, Mg and Ca increased; In the head, legs and wings of Mylabris, the contents of Hg and Pb elements were higher than those of the other parts. The content of As in the inner wings was the highest. CONCLUSION: The traditional processing method, stir-frying with rice and removing head, legs and wings is scientific.

[Comparison of cinnamic acid contents in Rhizoma Typhonii before and after being processed].

OBJECTIVE: To compare the diversity of contents of Cinnamic acid in Rhizoma Typhonii before and after being processed. METHODS: RP-HPLC. RESULTS: There were great difference of the contents of Cinnamic acid in various batch. The contents degraded after had been processed. CONCLUSION: Cinnamic acid in Rhizoma Typhonii can be separated completely under the condition of RP-HPLC. Precision and reproduction of the method is preferable. The method is simple, convenient, reliability and can be as a kind of method to determine the contents for Rhizoma Typhonii.