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.

Simultaneous determination of Se, trace elements and major elements in Se-rich rice by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) after microwave digestion.

A quick and accurate method was devised to determine Se, As, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn in Se-rich rice samples by microwave digestion and inductively coupled plasma-mass spectrometry (ICP-MS). Spectral interferences on Se were eliminated using methane as a reaction gas in the dynamic reaction cell (DRC). Rhodium was used as an internal standard to compensate for sample matrix effects. A rice-certified reference material (CRM) (GBW 10010) was used to verify the accuracy of the method. The method detection limits were 0.001-0.03 mg/kg, analyte recoveries were 85-108% and precisions (RSDs) ranged from 2.1% to 5.8%. Correlation analysis showed that the Se concentrations in the Se-rich rice samples correlated well with the Cu concentrations (r=0.53, p<0.05).