A Review of the Analytical Methods for the Determination of 4(5)-Methylimidazole in Food Matrices

4(5)-Methylimidazole (4(5)MEI) is a product of the Maillard reaction between sugars and amino acids, which occurs during the thermal processing of foods. This compound is also found in foods with caramel colorants additives. Due to its prevalence in foods and beverages and its potent carcinogenicity, 4(5)MEI has received federal and state regulatory agency attention. The aim of this review is to present the extraction procedures of 4(5)MEI from food matrices and the analytical methods for its determination. Liquid and gas chromatography coupled with mass spectrometry are the techniques most commonly employed to detect 4(5)MEI in food matrices. However, the analysis of 4(5)MEI is challenging due to the high polarity, water solubility, and the absence of chromophores. To overcome this, specialized sample pretreatment and extraction methods have been developed, such as solid-phase extraction and derivatization procedures, increasing the cost and the preparation time of samples. Other analytical methods for the determination of 4(5)MEI, include capillary electrophoresis, paper spray mass spectrometry, micellar electrokinetic chromatography, high-performance cation exchange chromatography, fluorescence-based immunochromatographic assay, and a fluorescent probe.

Water compatible imprinted polymer prepared in water for selective solid phase extraction and determination of ciprofloxacin in real samples

A novel water compatible ciprofloxacin imprinted polymer is synthesized in water via a green, non-toxic and environmentally friendly polymerization process. Hydrophilic groups, including anionic chlorine, hydroxyl, and carbonyl oxygen provided by a bifunctional monomer comprising 1-allyl-3-vinylimidazole chloride and 2-hydroxyethyl methacrylate, are introduced into the imprinted material, which allows the polymer to interact strongly with imprinting molecule via hydrogen bonds, electrostatic and π-π dipole interactions in aqueous solution. Rebinding experiments show that the obtained molecularly imprinted polymer (MIP) presents special molecular recognition towards quinolone antibiotics (ciprofloxacin, levofloxacin and pefloxacin mesylate) in aqueous matrices. The adsorption process of ciprofloxacin on MIP and non-imprinted polymer (NIP) substrates involves spontaneous exothermic reactions, and the maximum rebinding capacities of ciprofloxacin on MIP and NIP at 25 °C are 19.96 and 8.86 mg g^-1, respectively. The excellent selectivity and hydrophilicity of this imprinted polymer makes it suitable for use as an adsorbent in solid phase extraction. Under the optimized conditions, the presented MIP-SPE protocol exhibits a wide linear range between 0.29 and 1.47 × 10⁵ μg L^-1 and has been successfully applied for the separation and enrichment of trace ciprofloxacin in real water, soil and pork samples with satisfactory recoveries of 87.33-102.50%. The proposed study implies the promising prospect of this green and water compatible MIP in highly effective recognition and separation of trace quinolones in complex matrics.