Effective solid-phase extraction of chlorophenols with covalent organic framework material as adsorbent.

In this work, a porous extended network covalent organic framework designated as TP-NDA-COF was synthesized by the reaction of 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (TP) and 1,5-naphthalenediamine (NDA). The structure and morphology of the TP-NDA-COF was characterized by means of Fourier transform infrared spectra (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The TP-NDA-COF was applied as a solid-phase extraction adsorbent for the extraction of some chlorophenols from water and lemon black tea beverage samples prior to high performance liquid chromatography-UV detection. The main experimental parameters that affect the extraction efficiency including the type and volume of eluent, sample solution volume, sample loading rate and sample solution pH were investigated. Under the optimal conditions, the calibration curves were linear in the range of 0.30-60.0 ng mL-1 with the determination coefficients (R2) of 0.9996-0.9998 for water samples and in the range of 0.60-60.0 ng mL-1 with the R2 values from 0.9990 to 0.9996 for beverage samples. At the signal to noise ratio of 3 (S/N = 3), the method LODs for the analytes were 0.10-0.15 ng mL-1 for water samples and 0.20-0.50 ng mL-1 for lemon black tea beverage, respectively. Good repeatability was achieved with the relative standard deviations of less than 7%. The results showed that the SPE-HPLC method can be used for the determination of chlorophenols in environmental water and foodstuffs samples.

Facile synthesis of conjugated microporous polymer with spherical structure for solid phase extraction of phenyl urea herbicides.

A carbazolic conjugated microporous polymer (designated as CZ-CMP) was successfully synthesized through Scholl reaction of carbazole with 1, 3, 5-triphenylbenzene. The CZ-CMP was characterized by FT-IR spectrum, X-ray diffraction, nitrogen sorption isotherms, and scanning electron microscopy. The characterization results showed that the CZ-CMP had a spherical structure with high surface area and good microporosity. Its adsorption performance was investigated by applying it as an adsorbent for the solid phase extraction (SPE) of phenyl urea herbicides (PUHs) (metoxuron, chlortoluron, isoproturon, monolinuron and buturon) from tea drinks samples prior to high performance liquid chromatographic detection. The CZ-CMP displayed high extraction efficiency for the PUHs, and the primary factors affecting the SPE efficiency including the type and volume of the eluent, sample solution pH, sample loading rate and sample volume were optimized. Under the optimized conditions, a good linear response for the analytes was observed in the range of 0.10-80.0 ng mL-1 with correlation coefficients (r) from 0.9937 to 0.9997. The limits of detection were measured to be in the range of 0.02-0.30 ng mL-1 and the limits of quantitation were in the range of 0.06-0.9 ng mL-1. The developed method was successfully applied for the determination of the five PUHs in four different kinds of drinks with the method recoveries between 83.7% and 118% and the relative standard deviations between 1.0% and 10%. Besides, the application potential of the CZ-CMP was evaluated by using it to extract different types of the organic compounds including some phthalate eaters (PAEs), chlorophenol (CPs), nitroimidazoles and polycyclic aromatic hydrocarbons (PAHs). The results indicated that the CZ-CMP had strong adsorption ability for the compounds with more hydrogen bonding sites and moderate hydrophobicity.