Suspended Stir Bar Sorptive Extraction Based on Zr-MOF-Modified Cotton Thread for Enrichment and Detection of Three Trace Quinolones in Fish Tissue

In this study, an efficient and practical method was established to enrich and detect three trace quinolones in fish tissue. Low-cost and environment-friendly cotton threads were coated with PCN-224 using a simple one-pot hydrothermal method. The PCN-224-modified cotton threads (PCN-224@CTs) were characterized to ensure that the crystal was successfully fabricated on the surface of cotton threads. The prepared PCN-224@CTs were wrapped around steel needles to form suspended bars. Key factors of extraction and desorption were optimized, and analytical performance was tested. Suspended bar sorptive extraction coupled with ultra-performance liquid chromatography (UPLC) with a photodiode array detector was used to analyze the quinolones in fish tissue. The detection limits of quinolones were 0.26–1.15 ng/mL, and the recoveries were achieved in the range of 81.31%–115.81%, indicating a simple method with high sensitivity and satisfactory practicability of enriching, separating, and detecting trace quinolones was successfully established.