Hierarchical porous zeolitic imidazolate framework‑8 supported hollow-fiber liquid-phase microextraction of nine typical phenolic pollutants in water samples followed by electrophoretic analysis

Hierarchical porous zeolitic imidazolate framework‑8 (HpZIF-8) have not only good chemical and thermal stability, but also pore structures of different sizes. In this work, HpZIF-8 supported hollow-fiber liquid-phase microextraction (HpZIF-8@HF-LPME) co-modified with tributyl phosphate and 2-nitroethyl benzene was firstly developed for purification and enrichment of nine typical phenolic pollutants followed by electrophoretic separation and amperometric detection (CE-AD). The key enrichment parameters were optimized by full factorial experimental and central composite designs. Under the optimum conditions, the maximum enrichment factors for the nine analytes were 479 (phenol), 249 (2-chlorophenol), 821 (4-chlorophenol), 1253 (3-methylphenol), 1376 (2,4-dichlorophenol), 1078 (2,4,6-trichlorophenol), 200 (pentachlorophenol), 614 (4-nitrophenol) and1827 times (bisphenol A), respectively. The limits of detection were 0.060-1.5 µg L-1 (S/N = 3) in real sample matrixes. This proposed method has been successfully applied to water samples with high ionic strength, and the average recoveries were in the range of 80.2-118.0%. This developed method of HpZIF-8@HF-LPME/CE-AD needs no desorption and derivatization, providing an alternative for monitoring typical phenolic pollutants in water samples.

Benzoxazine Porous Organic Polymer as an Efficient Solid-Phase Extraction Adsorbent for the Enrichment of Chlorophenols from Water and Honey Samples

Porous organic polymers have gained great research interest in the field of adsorption. A benzoxazine porous organic polymer (BoxPOP) constructed from p-phenylenediamine, 1,3,5-trihydroxybenzene and paraformaldehyde was fabricated and explored as an adsorbent for solid-phase extraction (SPE) of four chlorophenols from water and honey samples. Under the optimized SPE conditions, the response linearity for the analysis of the SPE extract of the chlorophenols by high performance liquid chromatography-diode array detector was observed in the range of 0.2-40.0 ng mL-1 for water samples and 5.0-400.0 ng g-1 for honey samples. The method detection limits of the analytes were 0.06-0.08 ng mL-1 for water samples and 1.5-2.0 ng g-1 for honey samples. The recoveries of the analytes from fortified water and honey samples ranged from 84.8 to 119.0% with the relative standard deviations below 8.4%. The results indicate that the prepared BoxPOP is an effective adsorbent for the chlorophenols. The established method provides an alternative approach for the determination of chlorophenols in real samples.

Covalent Organic Framework as Fiber Coating for Solid-Phase Microextraction of Chlorophenols Followed by Quantification with Gas Chromatography-Mass Spectrometry

Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was adopted for the simultaneous determination of seven chlorophenols (CPs) from honey and canned-yellow-peach samples. A covalent organic framework made of 1,3,5-triformylphloroglucinol (Tp) and benzidine (BD) was used as the SPME fiber coating to preconcentrate the acetylation derivatives of the CPs. The main experimental parameters including derivatization conditions, extraction temperature and time, headspace volume, salt concentration, and desorption temperature were investigated. The fiber showed a high extraction capability for the CPs. The limits of detection (LODs) for the analytes were 0.3-0.7 μg kg^-1 for honey and 0.8-1.8 μg kg^-1 for canned-yellow-peach samples, suggesting good sensitivity for the method. The response linearity was 2.4-250 μg kg^-1 for 2-CP and 3,4-CP and 1.0-150 μg kg^-1 for the other remaining analytes in the honey samples. For the canned-yellow-peach samples, the response linearity was 6.0-300 μg kg^-1 for 2-CP and 3,4-CP and 3.0-200 μg kg^-1 for the others. The correlation coefficients were higher than 0.9919. Good repeatability (RSD < 11.9%) for the method and high recoveries (70.2-113%) of the analytes were observed under the optimal conditions. The established method was satisfactorily applied for the analysis of honey and canned-yellow-peach samples.

Chrysanthemum-like 3D hierarchical magnetic γ-Fe2O3 and Fe3O4 superstructures: facile synthesis and application in adsorption of organic pollutants from water

Chrysanthemum-like 3D hierarchical magnetic γ-Fe₂O₃ and Fe₃O₄ superstructures were successfully fabricated by a facile additive-free solvothermal method, which possess a high adsorption capacity for chlorophenols.