Task specific adsorbent based on porous monolith for efficient capture of synthetic colorants in beverages and preserved fruits prior to chromatographic analysis.

Efficient capture is an indispensable step in the highly sensitive quantification of synthetic colorants (SCs) in food industry. In this scenario, a new task specific adsorbent based on porous monolith (TSA) was conveniently fabricated and utilized as the adsorptive medium of multiple monolithic fibers solid phase microextraction (MF-SPME) for entrapment of SCs in beverages and preserved fruit samples. Various techniques were employed to characterize the prepared TSA and evidenced there were abundant functional groups, pores and satisfactory surface area. The introduced TSA/MF-SPME presented good entrapment performance towards SCs including sunset yellow, allura red and para red through multiple interactions. The enrichment factors were in ranges of 88-106 and 71-101 for beverage and preserved fruit, respectively. Under the optimized fabrication conditions of TSA and extraction parameters, sensitive and reliable method for the quantification of studied SCs in beverage and preserved fruit samples was developed by the combination of TSA/MF-SPME with HPLC/DAD. Limits of detection were 0.015-0.018 µg/L for beverage and 0.057-0.069 µg/kg for preserved fruit samples. The established approach also possessed some features such as wide linear ranges, good precision, low consumptions of sample and organic solvent. The applicability of suggestion method was verified by the quantification of investigated analytes in various beverage and preserved fruit samples, and good recoveries with different fortified concentrations were achieved.

Development of monolith/aminated carbon nanotubes composite-based solid-phase microextraction of phenoxycarboxylic acids herbicides in water and soil samples.

In this study, a new adsorbent based on monolith/aminated carbon nanotubes composite was facilely prepared and employed as the extraction phase of multiple monolithic fibers solid-phase microextraction for the capture of phenoxycarboxylic acids herbicides. The adsorbent was fabricated by mingling aminated carbon nanotubes in the poly (allylthiourea-co-ethylene glycol dimethacrylate) monolith. Various techniques were employed to characterize the morphology, structure, and pore size of the prepared adsorbent. The proposed microextraction method displayed satisfactory capture performance towards studied analytes through multi-interactions such as hydrogen-bonding, hydrophobic and π-π interactions. Under the optimized conditions, a sensitive and reliable method to quantify trace analytes in water and soil samples was developed. The limits of detection were in the ranges of 0.13-0.25 µg/L and 0.20-0.61 µg/kg for water and soil samples, respectively. The practicality of the introduced method was demonstrated by applying it to monitor the contents of studied analytes in environmental water and soil samples. Satisfactory fortified recoveries (76.4-119%) and reproducibility were obtained. The achieved results well demonstrated that the suggested microextraction technique can efficiently extract phenoxycarboxylic acids and the developed method exhibits a promising potential for reliable and sensitive quantification of trace analytes in complex samples.

Monolith/aminated graphene oxide composite-based electric field-assisted solid phase microextraction for efficient capture of phenoxycarboxylic acids herbicides in environmental waters.

Efficient capture of strongly polar, ionizable and trace phenoxycarboxylic acids herbicides (PCAHs) from aqueous samples is essential and challenging for environmental monitoring. In the present work, electric field-assisted solid-phase microextraction (EFA-SPME) based on monolith/aminated graphene oxide composite was developed for the first time to efficiently extract trace PCAHs prior to HPLC-tandem mass spectrometry (HPLC-MS/MS) quantification. First, poly (1-allyl-3-methylimidazole difluoromethanesulfonylamide salt-co-divinylbenzene/ethylene dimethacrylate) monolith/aminated graphene oxide composite (MAC) was prepared on the surface of stainless steel wire and employed as the extraction phase of SPME. After that, the MAC-based fiber and a stainless steel wire were connected to a DC power supply that allowed the implement of variable electric fields during adsorption and desorption processes. Various key factors influencing the extraction performance were inspected in detailed. Results well evidenced that the exertion of electric fields improved the enrichment performance, accelerated the trap and release procedures. The proposed MAC/EFA-SPME-HPLC-MS/MS method achieved wide linear ranges (0.005-50.0 µg/L), low limits of detection (0.54-1.3 ng/L) and good precision (2.7-7.0%) for the quantification of PCAHs. The related extraction mechanism was deduced. Additional, the current approach was successfully applied to monitor studied PCAHs at trace contents in environment waters, and the accuracy was confirmed by confirmatory experiments.

Development of magnetism-assisted in-tube solid phase microextraction of phenolic acids in fruit juices prior to high-performance liquid chromatography quantification.

Magnetism-assisted in-tube solid phase microextraction based on porous monolith mingled with Fe3 O4 nanoparticles was developed for capture of phenolic acids in fruit juices. First, poly (1-allyl-3-methylimidazolium bis [(trifluoro methyl) sulfonyl] imide-co-ethylene dimethacrylate) monolith embedded with Fe3 O4 nanoparticles was facile fabrication in a capillary and employed as microextraction column. Subsequently, a magnetic coil adopted to produce variable magnetic fields during extraction stage was twined on the microextraction column. The analytes contents in eluant were quantified by high performance liquid chromatogram with diode array detector. Various parameters affecting the extraction performance were inspected and optimized in detail. Results revealed that the exertion of magnetic fields in adsorption and desorption steps enhanced the extraction efficiencies of analytes from 44.9-64.0% to 78.6-87.1%. Under the optimal extraction factors, the limits of detection were between 0.012 and 0.061 µg/L, relative standard deviations for precision in terms of intra- and inter-day assay variability ranged from 1.9 to 9.8%. The introduced approach was successfully applied to simultaneously quantify the contents of five analytes in real fruit juices with satisfying fortified recoveries (80.1-116%). The obtained results well demonstrate the promising potential of the developed method in the highly sensitive quantification of trace phenolic acids in complex samples.