A composite based on cellulose and hyper-crosslinked polystyrene (cellulose-HCP) was developed as a novel sorbent for micro-solid-phase extraction (μSPE) using spin columns. The composite was prepared via a simple, low-cost, and environmentally friendly procedure based on cellulose dissolution in NaOH solution. The extraction conditions were systematically optimized with respect to sorbent amount, centrifugation parameters, solution pH, and desorption conditions. Quantitative extraction of fluoroquinolones (98%, RSD ≤ 2%) were achieved at pH 5.8 using spin columns packed with three composite disks and centrifugation at 1500 rpm for 1 min. Efficient desorption was obtained using an acetonitrile-ammonia mixture (1:1, v/v). The method was validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of fluoroquinolones in human serum. Good linearity was observed in the range of 2.0-400 μg L-1 (R2 ≥ 0.9916) with limits of detection of 0.3-0.7 μg L-1. Matrix effects were negligible (ME ≤ ±16%), and satisfactory reproducibility was achieved (RSD < 18%). The total sample preparation took 24 min and required only a centrifuge without protein precipitation. The proposed approach combines simplicity, rapidity, and low solvent consumption, meeting the principles of green sample preparation and demonstrating its suitability for the determination of fluoroquinolones in human serum.

Magnetite nanoparticles are proposed as a selective magnetic sorbent for the extraction of tetracyclines from both aqueous and organic media, with the sorption behavior systematically investigated as a function of contact time, sorbent mass, solution volume, and sorbate concentration. Under the optimized conditions, 20 mg of nanoparticles effectively isolated 94-100% of the analytes from 10 mL of aqueous, acetonitrile, ethyl acetate, or methanol solutions. It was demonstrated that a 0.1 M aqueous tetramethylammonium hydroxide solution can be used as an eluent compatible with mass spectrometric detection for the desorption of tetracyclines. Based on these findings, a magnetic solid-phase extraction method coupled with HPLC-MS/MS was developed for the determination of tetracyclines in honey, involving dissolution of the sample in methanol to extract the analytes, followed by acetonitrile addition to precipitate sugars, dilution of the resulting extract with water, and subsequent purification using magnetite nanoparticles. The proposed method exhibited good reproducibility (RSD 4-16%), low matrix effects (79-108%), and high sensitivity, with limits of detection and quantification of 0.3 and 1 μg kg⁻¹, respectively.

The effect of various catecholamines on the luminescent properties of silica nanodots (SiNDs) was studied and the new method using SiNDs that represent a promising green alternative to other analytical techniques for the determination of catecholamines has been developed. A change in spectral properties of SiNDs in the presence of catecholamines occurs, depending on the nature of the substance. Dopamine causes a decrease in the luminescence intensity of SiNDs at 445 nm whereas in the presence of norepinephrine and epinephrine a maximum appears in the luminescence spectrum of SiNDs at 500 and 510 nm, respectively. The intensity at 445 nm or the ratio of the intensities at 500 (510) nm and 445 nm can be used as analytical signals for the determination of the corresponding catecholamines. Limits of detection for dopamine, norepinephrine and epinephrine are 2, 0.06, and 0.14 mu M, respectively.

An approach to the extraction-fluorometric determination of sulfonamides (sulfanilamide, sulfamethazine, sulfamethoxazole) using a common color-recording device - i1Pro2 monitor calibrator is proposed. The determination is based on the preliminary derivatization of sulfonamides with fluorescamine and subsequent extraction of the luminescent product into a small volume of a water-immiscible organic solvent. Applying a monitor calibrator for measurements makes it possible to carry out the determination without separating the extract from the aqueous phase. To do this a black polymer membrane with a density less than that of water and higher than that of the organic phase should be used as a phase separator: it spontaneously locates at the phase boundary and serves as a bottom of a new cuvette in which measurements are carried out. Extraction of the analytes from 12.5 mL of the aqueous phase into 2.5 mL of the organic phase makes it possible to reduce the detection limit from 0.9 to 0.7 mu mol center dot L- 1 for sulfanilamide, from 0.8 to 0.4 mu mol center dot L- 1 for sulfamethazine and from 1 to 0.3 mu mol center dot L- 1 for sulfamethoxazole, increasing the ratio of volumes of the aqueous and organic phases further decreases the detection limit. The proposed method is applicable for the determination of sulfonamides in honey.

The possibility of luminescent and colorimetric determination of norepinephrine using silica nanodots (SiNDs), which are easily synthesized from available reagents, as well as using commercially available fluorescamine is demonstrated. Addition of epinephrine results in increasing luminescence for both types of the reagents that can be measured using a fluorometer or a smartphone. For the colorimetric determination, it is sufficient to use a budget smartphone costing about 20 USD with irradiation by an ultraviolet lamp with a wavelength of 395 nm. SiNDs used in both luminescent and colorimetric modes provide higher sensitivity compared to fluorescamine (detection limits are 0.06 and 0.1 mu M when using SiNDs and 0.3 and 0.5 mu M when using fluorescamine). The determination using SiNDs also has an advantage in terms of the cost of the reagents used and compliance with the principles of "green chemistry". A distinguishing feature of the studied approaches, compared with most methods currently known, is the increase of the observed fluorescent signal in the presence of a non-fluorescent analyte and without a quencher. To the best of our knowledge, it is the first colorimetric determination of norepinephrine using SINDs and fluorescamine. The proposed methods are applicable for the analysis of medicinal products.

An Erratum to this paper has been published: https://doi.org/10.1134/S1061934825010034

Сферические наночастицы серебра стали классическими нанообъектами, обладающими выраженными оптическими характеристиками, что привлекает к ним значительное внимание исследователей в области молекулярной абсорбционной спектроскопии, тест-методов и других сферах аналитической химии. Тем не менее сильное влияние морфологии на спектральные особенности наночастиц серебра создает благоприятную основу для изучения объектов несферической морфологии. Одним из интересных примеров таких объектов являются треугольные нанопластинки (ТНП). Их химические и спектральные особенности открывают обширные перспективы для исследований в области применения ТНП серебра в методах оптической молекулярной абсорбционной спектроскопии, дальнейшей интенсификации которых могут способствовать систематизация и обобщение основных сведений о вариантах получения и применения ТНП серебра в качестве аналитических реагентов. В статье, основывающейся на данных литературы и личном опыте авторов, представлена информация об основных способах синтеза этих нанообъектов, а также рассмотрены направления применения ТНП серебра и их композитных материалов в методах оптической молекулярной абсорбционной спектроскопии. Обсуждено влияние природы аналитов на характеристики их определения с помощью ТНП серебра, представлены примеры определения неорганических соединений и биологически активных органических веществ.

The magnetic hypercrosslinked polystyrene was used for the first time as a sorbent in effervescence-assisted magnetic solid-phase extraction. An effervescent tablet composed of magnetic hypercrosslinked polystyrene, sodium bicarbonate, and citric acid was used for extraction of nitroimidazoles and their metabolites from honey samples prior to their LC-MS/MS determination. In the proposed method, the dispersing of the sorbent occurs without the help of additional energy sources (such as ultrasound and stirring devices) due to the intensive release of carbon dioxide during dissolution of the tablet. The magnetic properties of the sorbent make it possible to separate it without the use of centrifugation or filtration. As a result, the extraction procedure takes only 3 min. The effects of important parameters, including the molar ratio of sodium bicarbonate to citric acid, mass of magnetic hypercrosslinked polystyrene, mass of the tablet, and desorption conditions, were systematically studied. The proposed method was validated using spiked honey samples. Under the optimum experimental conditions, the proposed method provided the limit of detection and limit of quantification of 0.3 and 1 μg kg−1, respectively. Precision values expressed as relative standard deviation were < 16

A magnetic solid-phase extraction method with the dispersion of magnetic hypercrosslinked polystyrene (MHCPS) by carbon dioxide is proposed for the extraction and preconcentration of amphenicols (chloramphenicol, florfenicol, and thiamphenicol) from honey and milk before their determination by HPLC–MS/MS. Effervescent tablets, consisting of sodium bicarbonate, citric acid, and MHCPS in the case of honey and sodium bicarbonate and MHCPS in the case of milk, were used. The conditions for obtaining tablets were selected (the amount and ratio of the acid, base, and MHCPS in the composition of a tablet and its mass), ensuring the quantitative release of amphenicols. Procedures for the determination of amphenicols in honey and milk with the dispersion of the sorbent by carbon dioxide and the subsequent determination of the compounds by HPLC–MS/MS are developed. The limits of detection are 0.3–1 and 0.02–0.05 μg/kg for honey and milk, respectively.

This review deals with methods for synthesis and fields of application of silicon-based nanoparticles (SiNPs). Physical, chemical and biogenic methods for the synthesis are systematized and described in detail, certain features of some approaches are highlighted, correlations between the synthesis conditions and SiNPs properties are discussed. The recent achievements in application of SiNPs for sensing of inorganic and organic compounds, improving the properties of detecting systems, creating sensors and visualizing cells are considered. The role and functions of SiNPs for solving some problems of analytical chemistry are elucidated.

Spherical silver nanoparticles have become classical nanoobjects with pronounced optical characteristics, which attracts considerable attention to them from researchers working in the field of molecular absorption spectroscopy, test methods, and other areas of analytical chemistry. Nevertheless, the strong influence of morphology on the spectral features of silver nanoparticles creates a favorable basis for studying nanoparticles of non-spherical morphology. An interesting example of such nanoobjects is provided by triangular nanoplates (TNP). Their chemical and spectral features open up broad prospects for research in the field of application of silver TNP in optical molecular absorption spectroscopy, the further intensification of which can be facilitated by the systematization and generalization of basic information about the variants for obtaining and using silver TNP as analytical reagents. This article, based on the literature data and the personal experience of the authors, provides information on the main methods for the synthesis of these nanoobjects, and also discusses the areas of application of silver TNP and their composite materials in optical molecular absorption spectroscopy. The influence of the nature of analytes on the characteristics of their determination using silver TNP is discussed, and examples of the determination of inorganic compounds and biologically active organic substances are presented.

Dispersive solid-phase extraction ( DSPE ) and magnetic solid-phase extraction ( MSPE ) are methods of solid-phase sorption preconcentration. Compared to classical solid-phase extraction, these methods have a number of advantages, such as reduced consumption of sorbents and solvents, extraction time, and cost of analysis. The popularity of the method among the analysts is evidenced by the large number of reviews we have summarized in this publication. Information is systematized on different versions of these methods, differing in the way the preconcentration process is carried out, the nature of the sorbents used, and their combination with methods for the subsequent determination of the preconcentrated substances; examples of using DSPE and MSPE for the separation of organic compounds in the analysis of environmental samples, food products and biological fluids are given.

A rapid multi-residue LC-MS/MS method for the identification and determination of banned veterinary drugs in honey was developed. A total of 31 investigated veterinary drugs belonging to 4 classes including nitrofurans metabolites, nitroimidazoles, amphenicols, and quinolones were quantified by LC-MS/MS with ESI using one single injection. The sample preparation included treatment with 5-nitro-2-furaldehyde (5-NFA) in a thermostated ultrasonic bath (80 degrees C, 0.5\M HCl, 20 min) to liberate matrix-bound residues of nitrofurans. Magnetic hypercrosslinked polystyrene (HCP/Fe3O4) was proposed for the solid-phase extraction and clean-up of target analytes prior to LC-MS/MS analysis. To evaluate and validate the performance of method, the criteria of the Decision (EC) no 2002/657 were applied. The LOQs of the examined analytes range from 0.3 to 1 mu g kg-1, which indicates good sensitivity to quantify the target compounds in honey. The recoveries of veterinary drugs from 1 g of honey with 50 mg of the sorbent are 97-109% for nitrofuran metabolites, 84-115% for nitroimidazoles, 86-103% for amphenicols, and 97-118% for quinolones. The relative standard deviations of intra-day and interday precision analyses (RSD) are less than 16%. This methodology was applied to real honey samples and trace levels of some veterinary drugs were detected.

The second and final part of the review. Provides general information about sub- and supercritical extraction (pressurized liquid extraction, subcritical water extraction, supercritical fluid extraction), matrix solid-phase dispersion and the QuEChERS method. Based on an analysis of review works, information on the features of sample preparation using these methods is systematized, experimental parameters affecting extraction efficiency are considered, and examples of using these methods for isolating organic compounds in the analysis of solid environmental samples, food products, and plants are given.

Adsorption of silver nanoparticles on polymers may affect the processes in which they participate, adjusting the analytical characteristics of methods for the quantitation of various substances. In the present study, a composite material based on silver triangular nanoplates (AgTNPs) and polyurethane foam was proposed for chemical analysis. The prospects of its application for the solid-phase/colorimetric determination of organic thiols were substantiated. It was found that aggregation of AgTNPs upon the action of thiols is manifested by a decrease in the AgTNPs’ localized surface plasmon resonance band and its significant broadening. Spectral changes accompanying the process can be registered using household color-recording devices and even visually. Four thiols differing in their functional groups were tested. It was found that their limits of detection increase in the series cysteamine < 2-mercaptoethanol < cysteine = 3-mercaptopropionic acid and come to 50, 160, 500, and 500 nM, respectively. The applicability of the developed approach was demonstrated during the analysis of pharmaceuticals and food products.

A possibility of using a monitor calibrator for the determination of luminescent compounds is shown on an example of quinine. The determination is based on the irradiation of a sample with broadband radiation in the visible and near UV spectral regions from a built-in source exciting phosphor molecules and the simultaneous registration of the radiation incident on the detector. Measurement conditions are selected. Quinine can be determined in the range of 60−750 µM, the limit of detection is 20 µM. The determination is not affected by common inorganic ions, as well as sweeteners and acidity regulators present in many beverages. The developed method of determination is applicable to the analysis of carbonated drinks and drugs. Compared to a traditional spectrofluorimeter, monitor calibrator is characterized by compactness, mobility, ability of detecting luminescence in cuvettes of various sizes and shapes, and lower cost.

Traces of medicinal formulations and their metabolites often remain in animal products. The presence of non-steroidal anti-inflammatory drugs (NSAIDs) in food is a factor of chronic human health effects. Therefore, improved methods for their determination are needed for food safety. Usually a complex sample preparation based on enzymatic, alkaline or acidic hydrolysis is applied to recover residual NSAIDs from their hydroxyl-, carboxyl-, glucuronide- and other derivatives to the original forms. This work focused on a systematic study and comparison of the sample preparation of real samples analysed for the presence of NSAIDs and their metabolites. The objects of analysis were meat and by-products obtained from chickens, which were given with preparations containing metamizole, diclofenac, ketoprofen, ibuprofen, meloxicam, phenylbutazone, and mefenamic acid together with their feed. The acidity of the extraction solution, the use of glucuronidase enzyme, different sorbents for purification by solid phase extraction were studied. By HPLC-MS, the hydroxyl- and carboxyl- metabolites were detected. It was shown that the long hydrolysis step during the sample preparation can be replaced with extraction into acetonitrile, making the full analytical procedure “whiter”.

Recently non-spherical nanoobjects attracted remarkable attention as promising reagents in optical molecular spectroscopy. One of the interesting types of non-spherical nanoparticles is silver triangular nanoplates (AgTNPs). They can be easily prepared and utilized for the development of sensitive probes for detection of various analytes. This review summarises different methods for the synthesis of AgTNPs. Both classical citrate and borohydride approaches and novel microwave/ultrasound-assisted methods, synthesis in organic solvents, photochemical, biological and biochemical methods are considered. The advantages and shortcomings of the main approaches are discussed in detail. The main areas of application of AgTNPs in optical molecular spectroscopy, such as UV-Vis spectrometry, diffuse reflectance spectroscopy and test analysis, are presented and compared. Methods for the determination of metal ions, anions, and organic compounds using AgTNPs are considered. The existing trends in these directions are outlined.

A possibility of the use of a common monitor calibrator as a portable and inexpensive tool for the fluorometric determination of sulfonamide drugs after their reaction with fluorescamine was examined. The luminescence measurements with a calibrator are based on irradiation of a test sample by the device lamp with a broadband spectrum in the visible and near UV regions and simultaneous registration of the secondary radiation by the device detector. Two types of cuvettes with black light absorbing sides eliminating the reflected self-radiation were tested. The commercially available Eppendorf-type black plastic microtubes ("LightSafe") were suggested as a good option for such measurements. It was shown that a monitor calibrator can be applied for optimization of the determination conditions. By the example of sulfanilamide and sulfamethazine, it was shown that the procedure should be carried out at pH 4-6 and fluorescamine concentration of 200 mu mol L-1, and 40 min of the interaction. The limit of detection of sulfanilamide and sulfamethazine using a monitor calibrator is 0.9 mu mol L-1 and 0.8 mu mol L-1, respectively, which is comparable with their spectrophotometric determination.