Vol 80, No 8 (2025)

Sample preparation of natural objects requires the development of highly sensitive and selective methods for extracting and concentrating biologically active substances. So-called smart materials, which are selected to solve specific analytical problems, are promising in this area. The review considers the main types of such materials (ionic liquids, eutectic solvents, nanomaterials, organometallic and covalent framework structures, molecularly imprinted polymers), their specific features and specific examples of application in chemical analysis for 2020-2025. The possibilities of using smart materials in the analysis of biological fluids and natural objects, available microextraction approaches and methods for subsequent determination are considered. The achieved advantages over previously proposed approaches are emphasized.

Prospects for the use of imidazolium ionic liquids (IL) as extractants of sex steroid hormones (estrogens and androgens) in microextraction methods (dispersive liquid-liquid microextraction, DLLME, and magnetic solid-phase microextraction, mSPME) are identified. The key parameters of DLLME using C₆MImNTf₂ IL, affecting the extraction efficiency, are optimized using the design of experiment method. High degrees of recovery (88–99 %) are achieved. An approach of dynamic IL immobilization on the surface of magnetic nanoparticles (MNPs) for steroid extraction under mSPME conditions is proposed. Two types of MNP pre-coating are studied: hydrophilic based on silica and hydrophobic with oleic acid. The capabilities of C₈MImBF₄ IL as a MNP surface modifier for efficient steroid extraction are revealed. Optimum conditions provided high degrees of recovery (83–97 %), with the exception of estriol (60 %). The detection limits are 0.26–1.29 ng/mL. Limitations of the method related to partial removal of IL from the surface of NPs are revealed, which reduces the reproducibility of the results for estriol.

A simple express procedure for gas chromatographic determination of ethanol in soft drinks is proposed (kvass, grape juice, non-alcoholic beer), based on headspace microextraction of the analyte into a drop (1 μL) of distilled water located above the surface of the analyzed liquid on the tip of the needle of a standard microsyringe for gas chromatography. The detection limit of ethanol is (3–6) × 10^–5 vol. %, the parallel determination time, including headspace extraction, does not exceed 5 min. Propanol-2, which is not detected in beverages, is used as an internal standard. The correctness of the procedure is confirmed by the added–found method, the relative standard deviation does not exceed 7 % at an ethanol concentration in the sample of 10^–2 vol. %.

Magnetic hypercrosslinked polystyrene (MHCPS) is proposed for group sorption isolation and preconcentration of quinolones. The conditions for magnetic solid-phase extraction are selected: 25 mL of solution (pH 6), sorbent mass 20 mg, sorption time 20 min. The analytes have been desorbed with 2 mL of methanol. It is shown that the sorbent provides quantitative isolation of all 23 studied compounds not only from aqueous solutions, but also from milk, bypassing the deproteinization stage. The determination is carried out by HPLC-tandem mass spectrometry using matrix calibration. The detection and determination limits of quinolones are 0.012–0.12 and 0.04–0.4 μg/L, respectively, which are below their maximum residue levels in milk.

Specific features of the preconcentration and determination of polycyclic aromatic hydrocarbons (PAHs) in humus-rich soils by gas chromatography–mass spectrometry (GC–MS) are studied. The QuEChERS technique and dispersive liquid–liquid microextraction (DLLME) were employed to extract PAHs from soils using acetone and binary extractants of various compositions, including acetonitrile–dichloromethane, acetonitrile–acetone, acetone–hexane, acetone–chloroform, acetone–dichloromethane, and ethyl acetate–dichloromethane. Recoveries of low- and medium-molecular-weight PAHs using these solvent mixtures reached approximately 100%, while the acetone–dichloromethane mixture yielded over 90% recovery for high-molecular-weight PAHs. Under optimized GC–MS conditions with QuEChERS extraction, the limits of quantification (LOQ) for fluoranthene, pyrene, chrysene, and triphenylene reached 5 μg/kg, and for the remaining PAHs, 10 μg/kg in humus-rich soils. It was shown that the reliable GC–MS determination of lower concentrations of PAHs requires both the elimination of the matrix effect and the preconcentration of the analytes. The sequential application of QuEChERS and DLLME techniques enabled a decrease in the limits of quantification by GC–MS to 1.8 μg/kg for fluoranthene, pyrene, chrysene, and triphenylene, and to 3.5 μg/kg for the remaining PAHs. The optimized procedure for PAH determination in humus-rich soils was validated using real chernozem samples.