Preparation and Application of Polymerized High Internal Phase Emulsion Monoliths for the Preconcentration and Determination of Malachite Green and Leucomalachite Green in Water Samples

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.

MIL-101(Fe)-derived magnetic porous carbon as sorbent for stir bar sorptive-dispersive microextraction of sulfonamides

Using MIL-101(Fe) as the source of carbon and Fe, a magnetic porous carbon (MPC) material with Fe₃C nanoparticles encapsulated in porous carbon was prepared through one-pot pyrolysis under N₂ atmosphere. With MPC as adsorption material, a stir bar sorptive-dispersive microextraction (SBSDME) method was proposed to extract and preconcentrate sulfonamides (SAs) prior to HPLC-DAD determination. To investigate their extraction ability, different MPC materials were prepared under different carbonization temperatures (600, 700, 800, 900, and 1000 °C). The material prepared under 900 °C (MPC-900) exhibited the highest extraction ability for SAs. The as-prepared MPC materials were also characterized by Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, zeta potential, and other techniques. The main parameters that affect extraction were systematically studied. Under optimal conditions, favorable linearity (R² ≥ 0.9938) and detection limits (0.02-0.04 ng mL^-1) of sulfonamides were obtained. The average recoveries for spiked milk and lake water samples ranged from 76.9 to 109% and from 75.4 to 118% with RSDs of 3.10-9.63% and 1.71-11.3%, respectively. Sulfameter and sulfisoxazole were detected in milk sample. Sulfisoxazole was detected in the lake water sample. The MPC-900 material demonstrated excellent reusability. It can be reused 24 times with peak areas having no obvious decline. The method can be applied to extract ultra-trace compounds in complex sample matrices. Schematic presentation of a stir bar sorptive-dispersive microextraction (SBSDME) by using magnetic porous carbon (MPC) composites as sorbent combined with high-performance liquid chromatography for sensitive analysis of sulfonamides in milk and lake water samples.

Macroporous Polymer Monoliths in Thin Layer Format

Nowadays, macroporous polymer monoliths represent widely used stationary phases for a number of dynamic interphase mass exchange processes such as high-performance liquid chromatography, gas chromatography, electrochromatography, solid-phase extraction, and flow-through solid-state biocatalysis. This review represents the first summary in the field of current achievements on the preparation of macroporous polymer monolithic layers, as well as their application as solid phases for thin-layer chromatography and different kinds of microarray.