Preparation of sheet-like covalent organic frameworks and their application for efficient preconcentration of 4-(tert-octyl)-phenol and 4-nonylphenol in textiles

• Published in: Journal of Chromatography A 2021-01, Vol.1635, p.461765, Article 461765
• Main Authors: Wu, Fang-Fang, Zhu, Yan, Zhao, Xu-Yang, Qian, Li-Qun, Wei, Yi-Li, Ma, Xiu-Juan, Ye, Ming-Li, Cui, Hai-Rong
• Format: Article
• Language: English
• Subjects: Alkylphenol; Covalent organic frameworks (COFs); Dispersive solid-phase extraction (dSPE); LC-MS/MS; Textiles
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2020.461765

•The novel sheet-like COFs have been designed and synthesized.•The dSPE procedure using COFs as sorbent has been developed.•Sheet-like COFs-II is more effective for the preconcentration of alkylphenol compared to sheet-like COFs-I.•LODs are significantly lower than other reported LC-MS/MS-based methodologies.•The method is efficient and promising for the applicability to routine analysis of alkylphenol. In the design of highly ordered (covalent organic frameworks) COFs with “ordered domains size and orientation” construction in a well-defined arrangement, the molecular monomers are the key factors. Here, the effect of molecular monomers on the construction of COFs has been studied, and two kinds of molecular monomers, i.e., ethanediamine (flexible amine ligand) and 4,4′-diaminobiphenyl (rigid amine ligand) have been used for developing sheet-like COFs-I and sheet-like COFs-II, respectively. Furthermore, they have been evaluated in the dispersive solid phase extraction (dSPE) procedure for textiles prior to the analysis of alkylphenol by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). The results showed that, the optimal usage amount of sheet-like COFs-II used in the dSPE procedure was less than that of sheet-like COFs-I, which may be explained by much higher adsorption capacity of sheet-like COFs via hydrogen-bonding and π-π stacking interactions. Rectilinear calibration graphs were obtained for 4-(tert-octyl)-phenol (4-tOP) and 4-nonylphenol (4-NP) in the range 0.2-20 µg/kg with determination coefficient (r2) higher than 0.9990, and the limits of detection (LODs) of 4-tOP and 4-NP were 0.039 µg/kg and 0.048 µg/kg, respectively. The developed method has been successfully applied to analysis of 50 textile samples, in which 4-tOP and 4-NP were found in six samples with concentrations in the range of 1.6 μg/kg-20.9 μg/kg.