PEGylation of magnetic multi-walled carbon nanotubes for enhanced selectivity of dispersive solid phase extraction

Magnetic carbon nanotubes-molecularly imprinted polymer coupled with HPLC for selective enrichment and determination of ferulic acid in traditional Chinese medicine and biological samples

A molecularly imprinted polymer (MIP) with magnetic carbon nanotubes (MCNTs) as carrier was synthesized and used for the enrichment and determination of ferulic acid (FA) by high-performance liquid chromatography (HPLC). The morphology and structure of the FA magnetic carbon nanotubes-molecularly imprinted polymers (MCNTs@FA-MIPs) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results demonstrated that the prepared MCNTs@FA-MIPs had excellent magnetic properties and uniform appearance. The adsorption properties of the novel MIP were studied by kinetic, and isothermal adsorption experiments. The results showed that the MCNTs@FA-MIPs exhibited relatively good uptake kinetics (equilibrium time, 2 h), high adsorption capacity (50 mg⋅g-1), fast separation, and good selectivity for the template molecule with a separation factor α of 1.73. The MCNTs@FA-MIPs combined with HPLC were successfully applied to the separation, enrichment, and determination of FA in a Ligusticum chuanxiong extract and in plasma of rats which had been administered with Taitai beauty essence. The recoveries for FA were 95.53-100.03 % with relative standard deviations (RSDs) less than 5.5%. The results confirmed that the proposed MCNTs@FA-MIPs offered efficient extraction of FA from traditional Chinese medicinal preparations and blood samples and with high specificity.

Recent Materials Developed for Dispersive Solid Phase Extraction

Solid phase extraction (SPE) is an analytical procedure developed with the purpose of separating a target analyte from a complex sample matrix prior to quantitative or qualitative determination. The purpose of such treatment is twofold: elimination of matrix constituents that could interfere with the detection process or even damage analytical equipment as well as enriching the analyte in the sample so that it is readily available for detection. Dispersive solid phase extraction (dSPE) is a recent development of the standard SPE technique that is attracting growing attention due to its remarkable simplicity, short extraction time and low requirement for solvent expenditure, accompanied by high effectiveness and wide applicability. This review aims to thoroughly survey recently conducted analytical studies focusing on methods utilizing novel, interesting nanomaterials as dSPE sorbents, as well as known materials that have been only recently successfully applied in dSPE techniques, and evaluate their performance and suitability based on comparison with previously reported analytical procedures.

Multi-mycotoxins analysis in liquid milk by UHPLC-Q-Exactive HRMS after magnetic solid-phase extraction based on PEGylated multi-walled carbon nanotubes

A simple and rapid magnetic solid-phase extraction (MSPE) method using PEGylated multi-walled carbon nanotubes magnetic nanoparticles (PEG-MWCNTs-MNP) as absorbents is proposed for isolation and enrichment of aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁), aflatoxin G₂ (AFG₂), aflatoxin M₁ (AFM₁), aflatoxin M₂ (AFM₂), ochratoxin A (OTA), zearalenone (ZEA), zearalanone (ZAN), α-zeralanol (α-ZAL), β-zeralanol (β-ZAL), α-zeralenol (α-ZOL), and β-zeralenol (β-ZOL) from liquid milk. Combined with ultra-high performance liquid chromatography Q-Exactive high resolution mass spectrometry, simultaneous qualification of these mycotoxins was achieved with sensitivity and specificity. The proposed method showed a good linearity (R² ≥ 0.995), high sensitivity (limit of detection in the range of 0.005-0.050 μg/kg and limit of quantification in the range of 0.015-0.150 μg/kg), adequate recovery (81.8-106.4%), and good repeatability (intra-day precision in the range of 2.1-8.5% and inter-day precision in the range of 3.9-11.7%). It has been successfully applied to the determination of 13 mycotoxins in real liquid milk samples.