Synthesis of azo-linked covalent organic polymers for pipette tip solid-phase extraction of sedative residues from animal tissues samples.

Azo-linked covalent organic polymers (ACOPs) were synthesized by a simple azo reaction, with 2,2'-bis(trifluoromethyl)benzidine and 1,3,5-trihydroxybenzene as the monomers. The preparation process was mild, green, and environmental-friendly, avoiding the use of high temperature, metal catalysis, and harmful organic reagent. The obtained ACOPs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and Brunauer-Emmett-Teller. With the prepared ACOPs as adsorbent, a method of pipette tip solid-phase extraction-liquid chromatography-tandem mass spectrometry detection (PTSPE-LC-MS/MS) was proposed for the analysis of target sedatives in animal tissues. Furthermore, the parameters for the extraction of five sedatives, including the amount of adsorbent, pH value, ion strength, elution solvent and volume, were investigated. Under the optimized conditions, the linear dynamic range was found from 0.1 to 10.0 µg kg-1, and the limits of detection were ranged from 0.02 to 0.1 µg kg-1. The method was assessed by the analysis of target sedatives in animal tissues, and the recoveries for the spiked pork muscle and pork liver samples were 84-102% and 83-101%, respectively. The results show that the developed method of PTSPE-LC-MS/MS with ACOPs as adsorbent is efficient for the analysis of trace sedatives in animal tissues.

Does the institutional environment influence corporate social responsibility? Consideration of green investment of enterprises-evidence from China.

Green investment, as a socially responsible investment, conforms to the concept of ecological civilization. It is considerable to promote enterprises to make green investment. This article is based on 211 questionnaires for employees of various enterprises in China, using STATA.14 for descriptive statistical analysis, logistical regression analysis, and trend analysis. It aims to explore the impact of government-led institutional environment on enterprises from five aspects. This study examines that the institutional environment has a positive effect on enterprise' green investment from the legal and cultural aspects, but it has no significant impact from the political, economic, and financial aspects. Finally, this paper provides policy advice that can promote the construction of institutional environment to encourage enterprises to make green investment.

Detection of azithromycin residue in broiler feathers by liquid chromatography-tandem mass spectrometry.

In the study, a sensitive and reproducible method for the quantitative analysis of azithromycin in broiler feather samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. Feather samples were rinsed after being wrapped in medical gauze, then chopped and then added to 5% (v/v) ammonia in methanol solution for ultrasonic extraction. The extract was purified by the combination of commercial polymeric microparticles (Oasis MCX) and Fe3O4 nanoparticles. The LC separation was performed on an Agilent Eclipse plus C18 column. Multiple reaction monitoring was used for the selective detection of azithromycin. The good linearity curve of azithromycin in feather sample was in the range from 1.0 µg kg-1 to 100.0 µg kg-1 with 0.9935 of correlation coefficient. And the limit detection and limit of quantification was 0.5 µg kg-1 and 2.0 µg kg-1 in spiked feather samples. The recoveries of azithromycin were 85.2-94.7% with the relative standard deviation less than 10%. The established method is simple, rapid, sensitive and specific, and could meet the need of government and enterprises to monitor the illegal use of azithromycin in livestock and poultry breeding.