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The aromatic structure and the rich nitrogen content of polymers based on covalent triazine-based frameworks (CTF) and their unique hydrophilic-lipophilic-balanced adsorption properties make them promising candidates for an adsorbent that can be used for sample pretreatment. Herein, a new covalent triazine-based framework (CTF-DBF) synthesized by a Friedel–Crafts reaction was used for the determination of the content of nucleotides in commercial infant formula. It was shown that the synthetic materials had an amorphous microporous structure, a BET surface area of up to 595.59 m2/g, and 0.39 nm and 0.54 nm micropores. The versatile adsorption properties of this material were evaluated by quantum chemistry theory calculations and batch adsorption experiments using five nucleotides as probes. The quantum chemistry results demonstrated that CTF-DBF can participate in multiple interactions with nucleotides. All the analyses performed present good linearity with R2 > 0.9993. The detection limits of targets ranged from 0.3 to 0.5 mg/kg, the spiked recoveries were between 85.8 and 105.3% and the relative standard deviations (RSD, n = 6) were between 1.1 and 4.5%. All these results suggest that this versatile CTF-DBF has great potential for sample pretreatment. [ABSTRACT FROM AUTHOR]

A solid-phase extraction (SPE) method was established for fipronil and its metabolite residues (fipronil desulfinyl, fipronil sulphone and fipronil sulphide) in eggs with a covalent triazine framework (CTF) porous material as the adsorbent followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection. Multiple probes and quantum chemistry theory calculations were conducted to describe the versatile adsorption property directly and quantifiably. The conjugated structure of CTF and N-containing triazine generated π-π interactions and hydrogen bonds between the CTF and the targets, which led to high extraction efficiency and recoveries. The solid-phase extraction parameters, including amount of the adsorbent, type of eluent, amount of eluent and loading rate were investigated. Under the optimal experimental conditions, the recoveries of the analytes were between 85.5% and 103.2%, and the RSD (n = 5) was between 1.8% and 3.6%. The LODs and LOQs were 0.13–0.2 ng g−1 and 0.5–0.8 ng g−1, respectively. The sorbent can effectively reduce the interference of the matrix and meet the detection requirements of fipronil and its metabolites in eggs. These results imply that the CTF as adsorbents have great potential in the analysis of trace targets in samples with complex matrices. [ABSTRACT FROM AUTHOR]

A novel dual-shell magnetic nanoparticle coated with a cationic covalent organic framework, containing ethidium bromide, is easily prepared, characterized and applied as an adsorbent for fast, simple and highly selective capture of nine hydroxylated polycyclic aromatic hydrocarbons in urine samples of non-smokers and smokers who smoked cigarettes with different tar yields. This is the first time that a cationic crystalline framework with high thermal and chemical stability was used for magnetic solid phase extraction. Multiple probes and quantum chemistry theory calculations were conducted to describe the versatile adsorption property directly and quantifiably. A method using high-performance liquid chromatography with a fluorescence detector based on the prepared magnetic adsorbent was established and used to investigate differences in the exposure levels of OH-PAHs in non-smokers and smokers smoking cigarettes with different tar yields. All the OH-PAH analyses present good linearities in the range of 0.1–100 ng mL−1, with R2 > 0.9965. The LOD for the 9 OH-PAHs ranged from 0.0030 to 0.0096 ng mL−1 and the LOQ ranged from 0.096 to 0.030 ng mL−1. The recoveries of the 9 OH-PAHs ranged from 93.3 to 121.3% with the RSD ranging from 0.47 to 3.53%. These results imply that the versatile EB-DS MNPs as adsorbents have great potential in the analysis of trace targets in samples with complex matrices. [ABSTRACT FROM AUTHOR]

Abstract Calixarenes and their derivatives have been widely used in chromatographic studies due to unique host-guest recognition properties. However, stationary phases in hydrophilic interaction chromatography associated with them have yet to be studied because of their general hydrophobicity. In this paper, a tetra-proline modified calix[4]arene bonded stationary phase (DTPCSP) was prepared and characterized by FT-IR spectra, elemental analysis, solid state 13C NMR, SEM, EDS and thermogravimetric analysis. The chromatographic performance and retention mechanism of the developed stationary phase were validated in hydrophilic interaction mode and compared with a commercial column using a variety of hydrophilic or hydrophobic compounds including phenols, nucleosides and sulfonamides. The developed stationary phase exhibited better selectivity than conventional calixarene phases, and the retention behaviors of phenols on DTPCSP column were elucidated by the calculation of quantum chemistry using ODS as contrast. All the results indicate that the developed DTPCSP stationary phase can be beneficial for simultaneously separating complex hydrophilic samples with high selectivity. Graphical abstract fx1 Highlights • A novel tetra-proline modified calix[4]arene bonded stationary phase (DTPCSP) was prepared and characterized. • DTPCSP exhibited better selectivity and separation capacity than commercial HILIC column. • DTPCSP can be beneficial for simultaneously separating complex hydrophilic samples based on a multiple interaction. [ABSTRACT FROM AUTHOR]