Covalent organic framework-graphene oxide composite: A superior adsorption material for solid phase microextraction of bisphenol A.

Novel materials with high adsorption and desorption efficiencies are significant for studying compounds at ultra-trace level. Herein, covalent organic framework-graphene oxide (COF-GO) composite materials are synthesized, and tested for solid phase microextraction (SPME) of bisphenol A (BPA) at ultra-trace level. With GO modified successively by 3-aminopropyltriethoxysilane, 1,3,5-triformylphloroglucinol (Tp), and different ratios of COF monomers (Tp and benzidine (BD)), the composites of TpBD-GO-n (n = 1-4) are synthesized. By coating the composites on a glass fiber, the extraction performances of the composites for BPA are tested with constant flow desorption ionization mass spectrometry (CFDI-MS). The extraction efficiency of the composite TpBD-GO-2 is 2.2 and 4.7 times higher than those of TpBD and GO, respectively. The chromatographic separation becomes a non-essential step for detection of BPA, the analysis time for each sample is reduced to 8 min. The limits of detection and quantification of MS for BPA analysis are improved to be 22.2 and 73.9 ng L-1. The linear range is extended to be 10.0 μg L-1 (R2 = 0.9990), and the relative standard deviations of one fiber (n = 11) and fiber-to-fiber (n = 8) are 4.3% and 5.6% (1 μg L-1), respectively. With this method, ultra-trace levels of BPA present in river water and sea water samples can be successfully detected and quantified. The results indicate that the TpBD-GO-n composites possess superior extraction performance, and their various applications could be expected.