Synthesis of Magnetic Azo-Linked Covalent Organic Polymer for Rapid Extraction of β-Agonists in Swine Urine Samples

The illegal use of β-agonists as feed additives can harm animal-derived food safety. In this study, a detection method for β-agonists in swine urine was established by the combination of azo-linked covalent organic polymer-miniaturized magnetic solid-phase extraction. The main factors that affect the extraction procedure were optimized. The designed adsorbent had good reusability, reproducibility, and stability. Under optimal conditions, the method achieved a good linear correlation coefficient (> 0.99) and a low detection limit (0.01 µg/L). The recoveries of the proposed method in swine urine samples for the simultaneous determination of β-agonists were in the range of 84.3%-99.4%, and the relative standard deviations were less than 6.5%.