Core–shell SiO₂‐coated Fe₃O₄ with a surface molecularly imprinted polymer coating of folic acid and its applicable magnetic solid‐phase extraction prior to determination of folates in tomatoes

Abstract

A novel core-shell magnetic surface molecularly imprinted polymer with folic acid as a template was successfully synthesized by the sol-gel method. To generate Lewis acid sites in the silica matrix for the interaction of the metal coordinate with the template, 3-aminopropyltriethoxysilane was used as a functional monomer, tetraethyl orthosilicate as a cross-linker, and aluminum ions as a dopant. The magnetite encapsulated by the silica shell plays an important role as a magnetic-coated polymer. The synthesized product was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and FTIR and UV/Vis spectroscopy. The powder X-ray diffraction patterns, FTIR and UV/Vis spectra confirmed the characteristics of the as-prepared silica coated magnetite and folic acid molecularly imprinted polymer. It was successfully applied for magnetic solid-phase extraction prior to the determination of folates in tomato samples using high-performance liquid chromatography with photodiode array detection. The detection limit of the proposed method was 1.67 μg/L, and results were satisfactory, with a relative standard deviation of < 3.94%.

Highly selective and efficient imprinted polymers based on carboxyl‐functionalized magnetic nanoparticles for the extraction of gallic acid from pomegranate rind

“…In recent years, molecular imprinting solid‐phase extraction has been extensively used to efficiently separate trace compounds from complex matrixes . For example, molecular imprinting solid‐phase extraction was used to extract thiabendazole from citrus , folates from tomatoes , bovine hemoglobin from the bovine blood , and GA from natural resources . Hu et al.…”

“…In recent years, molecular imprinting solid-phase extraction has been extensively used to efficiently separate trace compounds from complex matrixes [18][19][20][21]. For example, molecular imprinting solidphase extraction was used to extract thiabendazole from citrus [22], folates from tomatoes [23], bovine hemoglobin from the bovine blood [24], and GA from natural resources [25][26][27]. Hu et al prepared MIPs on magnetic mesoporous silica for the selective extraction and determination of GA from grape, apple, peach, and orange juices [25].…”

Surface modified‐magnetic nanoparticles by molecular imprinting for the dispersive solid‐phase extraction of triazines from environmental waters

“…All mixtures were prepared using a mixture of ACN/toluene (75/25, v/v) as porogen up to a final volume of 25 mL and subjected to thermal polymerization at 60 • C for 24 h. Once polymerization was complete, it was observed that polymerization did not occur for mixtures containing a 1:1 MAA/HEMA ratio (MMIP3 and NMIP3). It has been reported that the presence of hydrophilic monomers leads to polymers with insufficient rigidity [16]. In this regard, likely the large amount of HEMA used for the preparation of MMIP3 and NMIP3 did even prevent the polymerization process and consequently, such mixtures were discarded for further experiments.…”

“…It is clear that the incorporation of an MIP layer to magnetic nanoparticles presents significant advantages in sample preparation, taking into account the extraction efficiency provided by the surface modified magnetic nanoparticles and the extraction selectivity provided by MIPs [9,10]. At this regard, several works have reported the preparation of molecularly imprinted core-shell magnetic nanoparticles (MMIPs) to be used in magnetic dSPE and have been employed for the extraction of pesticides [11][12][13], triazophos [14], aflatoxins [15], and folates [16], among others. Analytes are selectively separated from the correspond-ing organic extract of different kind of samples although the application to water-based samples is rather scarce due to poor recognition abilities of MIPs in aqueous samples.…”

Molecularly imprinted polymers for the selective extraction of tiliroside from the flowers of Edgeworthia gardneri (wall.) Meisn

“…Attributing to the specific synthetic method, MIPs own a specific memory function and possess the performances of high selectivity and recognition ability to the target compounds . In recent years, MIPs have been widely used as separation media in SPE and SPME . They are also used in the fields of chromatographic separation , chemical sensor etc.…”