Synthesis of spindle-like amino-modified Zn/Fe bimetallic metal-organic frameworks as sorbents for dispersive solid-phase extraction and preconcentration of phytohormoes in vegetable samples.

Amino-modified Zn/Fe bimetallic metal-organic frameworks (NH2-Zn/Fe-MIL-88) were synthesized using a one-step solvothermal method with FeCl3·6H2O and Zn(NO3)2·6H2O as metal salts and 2-aminoterephthalic acid as organic ligand. The morphology of NH2-Zn/Fe-MIL-88 can be regulated from octahedral-like to spindle-like with changing molar ratios of metal salts. Using NH2-Zn/Fe-MIL-88 as sorbent, a dispersive solid-phase extraction with putting sorbents into sample solution to extract targets was developed to preconcentrate phytohormones in vegetables. To study the extraction efficiency, a series of NH2-Zn/Fe-MIL-88s with varying molar ratios of metal salts were prepared. The results indicated that NH2-Zn/Fe-MIL-88(1) presented the highest extraction efficiency (82.6 %-98.1 %) to phytohormones among all prepared NH2-Zn/Fe-MIL-88(x). The limits of detection were calculated at 0.07-0.15 ng/mL. The adsorption isotherms and kinetic parameters of NH2-Zn/Fe-MIL-88 for phytohormones were conformed to Langmuir and pseudo-second-order models. The NH2-Zn/Fe-MIL-88 as sorbent combined with HPLC was applied to detect phytohormones in cucumber and tomato samples.

Newly designed molecularly imprinted 3-aminophenol-glyoxal-urea resin as hydrophilic solid-phase extraction sorbent for specific simultaneous determination of three plant growth regulators in green bell peppers.

A method based on solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC) was developed to determine the content of 4-chlorophenoxy acetic acid (PCPA), naphthylacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in green bell peppers. A molecularly imprinted 3-aminophenol-glyoxal-urea resin (MIAGUR) was first synthesized as a specific SPE adsorbent, which exhibited special selectivity and multiple adsorption interactions including hydrogen bonding and π-π interactions. The quantities of PCPA, NAA and 2,4-D in green bell peppers from 20 samples scattered throughout Baoding city (Hebei province, China) were determined using the proposed method. The results suggested that the use of PCPA, NAA and 2,4-D in green bell peppers from Baoding's markets is almost in fair. Moreover, MIAGUR-SPE-HPLC is suitable for the specific simultaneous monitoring of PCPA, NAA, and 2,4-D in green bell peppers and has potential applications in determination of PCPA, NAA, and 2,4-D of other plant products.