Solid-phase extraction of phenols using UiO-66-NH2 metal–organic framework coated frits

Abstract

Metal-organic frameworks have shown a great potential as adsorbents for analytical sample preparation. However, there is currently a shortage of straightforward and efficient methods that allow the integration of metal–organic frameworks onto low-pressure flow-through supports to serve this purpose effectively. This is limiting the further development of metal–organic framework applications as sorbents for cartridge-based solid-phase extraction. Herein, a simple strategy to incorporate metal–organic frameworks on commercial solid-phase extraction frits using polyvinylidene difluoride as polymer binder is presented. The performance of the prepared metal–organic framework-coated frits was evaluated using immobilized UiO-66-NH2 nanoparticles as a model metal–organic framework for the extraction and preconcentration of bisphenol A, 4-tert-octylphenol, 4-n-nonylphenol, 4-cumylphenol, and 4-octylphenol as model analytes. Under the optimal solid-phase extraction conditions, limits of detection were ranging from 0.04 μgL−1 to 0.67 μgL−1. RSDs for batch-to-batch reproducibility were in the range of 3.1 %-5.8 % for three metal–organic framework-coated frits prepared on different days. Analyte recoveries for spiked samples ranged between 94 % and 109 % for tap water, and 87 %-110 % for bottled drinking water. The resulting metal–organic framework-coated frits are directly fitted onto commercial solid-phase extraction cartridges, and the subsequent extractions can be carried out without the need for additional packed particles, or frits. The developed approach enables the development of analytical methods based on solid-phase extraction in cartridge format with no limitations regarding the particle size and shape of the selected sorbent.