Zr-based metal-organic framework-modified cotton for solid phase micro-extraction of non-steroidal anti-inflammatory drugs.

A novel metal-organic framework UiO-66-modified cotton was prepared and applied to solid phase microextraction of non-steroidal anti-inflammatory drugs, namely ketoprofen, naproxen and flurbiprofen. UiO-66 was immobilized onto the surface of cotton by a polydopamine functionalized method. The resultant cotton@PDA@UiO-66 was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The solid phase microextraction conditions were optimized, including sampling flow rate, formic acid content of the eluent, pH value of sample solution, NaCl content and sample volume. By combining with HPLC, this method showed high extraction efficiency (the enrichment factors of ketoprofen, naproxen and flurbiprofen were 44, 49 and 45, respectively), wide linear range (0.1-500 ng/mL), good linearity with R ≥ 0.9996 and satisfactory sensitivity (LODs ≤ 0.03 ng/mL, LOQs ≤ 0.1 ng/mL), as well as good reproducibility (RSD ≤ 4.51%). This method was also successfully applied to extraction of NSAIDs in swine muscle sample. Good recoveries were obtained, ranging from 88.54% to 95.7% with relative standard deviations less than 3.77%.