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We proposed a procedure for the rapid sample preparation of food samples for the determination of nitrofuran metabolites in them by HPLC-MS/MS, using 5-nitro-2-furaldehyde as a new derivatizing agent. Meat samples from broiler chickens treated with nitrofurans for 10 days were used to demonstrate that the time of hydrolysis-derivatization in a thermostated ultrasonic bath could be significantly shortened by raising temperature to 80°C and increasing the concentration of hydrochloric acid to 0.5 M. Metabolites of Furaltadone, Furazolidone, Nitrofurantoin, and Nitrofurazone in chicken meat, liver, stomach, and heart are determined using the developed procedure and an official method. The proposed method ensures the quantitative isolation of metabolites., Author(s): A. O. Melekhin [sup.1] [sup.2] , V. V. Tolmacheva [sup.1] , Yu. N. Kholyavskaya [sup.2] , E. S. Sedykh [sup.2] , S. G. Dmitrienko [sup.1] , V. V. Apyari [...]

5-Nitro-2-furaldehyde is proposed as a new derivatizing agent for determining four nitrofuran metabolites: 3-amino-2-oxazolidinone, 3-amino-5-methylmorpholino-2-oxazolidinone, 1-aminohydantoin, and semicarbazide in chicken eggs by HPLC with tandem mass spectrometric detection. The derivatization products were identified; they are the initial nitrofurans: furazolidone, furaltadone, nitrofurantoin, and nitrofurazone, respectively. Sample preparation includes acid hydrolysis, derivatization, fat removal by hexane extraction, and the further purification of the extracts on cartridges packed with Diapak P-3 hypercrosslinked polystyrene. The method ensures the quantitative isolation of metabolites (recovery rates are 95 to 106%) and good reproducibility (RSD [less than or equal to] 13%)., Author(s): A. O. Melekhin [sup.1] [sup.2], V. V. Tolmacheva [sup.1], E. G. Shubina [sup.2], S. G. Dmitrienko [sup.1], V. V. Apyari [sup.1], A. I. Grudev [sup.2], Yu. A. Zolotov [sup.1] [...]

Hypercrosslinked polystyrene is proposed for the multicomponent solid-phase extraction of residues of 63 veterinary preparations from various classes (sulfonamides, tetracyclines, quinolones, amphenicols, nitroimidazoles, [beta]-lactams, macrolides, lincosamides, and pleuromutilins) in their determination in chicken meat by HPLC-tandem mass spectrometry. Sample preparation includes the extraction of analytes with a McIlvaine buffer solution, fat removal by extraction with hexane, and the further purification of the extracts on cartridges with hypercrosslinked polystyrene. The method ensures the quantitative extraction of analytes (recovery rates are from 83 to 117%) and good reproducibility (RSD [less than or equal to] 12%). Veterinary preparations were identified by the exact masses of analyte ions formed in electrospray ionization on switching positive and negative polarity. The matrix effect for all veterinary drugs was below 20%. The determination was carried out by the method of matrix calibration; the limits of detection and determination were 0.01-0.3 and 0.02-1 ng/g, respectively. An analysis of contaminated chicken meat samples showed that the results are in satisfactory agreement with the data obtained by the methods adopted in the Russian Federation for the determination of various groups of antibiotics., Author(s): A. O. Melekhin [sup.1] [sup.2], V. V. Tolmacheva [sup.1], E. G. Shubina [sup.2], S. G. Dmitrienko [sup.1], V. V. Apyari [sup.1], A. I. Grudev [sup.2] Author Affiliations: (1) grid.14476.30, [...]

Single-drop microextraction (SDME) and hollow-fiber membrane microextraction (HFME) belong to methods of the liquid-phase microextraction preconcentration of organic compounds. These methods are characterized by the low consumption of organic solvents, high preconcentration factors, simplicity, low cost, ease of combination with various chromatographic methods; processes of preconcentration and sample injection are combined in a single device. Since the emergence of SDME (1996) and HFME (1999), a large number of versions have been developed that differ in the preconcentration technique, nature of the extractants used, and combinations with methods for the subsequent determination of the preconcentrated substances. The popularity of these methods among the analysts is evidenced by many reviews that we have summarized in this publication., Author(s): S. G. Dmitrienko [sup.1], V. V. Apyari [sup.1], V. V. Tolmacheva [sup.1], M. V. Gorbunova [sup.1] Author Affiliations: (1) grid.14476.30, 0000 0001 2342 9668, Department of Chemistry, Lomonosov Moscow [...]

Published data on various versions of the homogeneous liquid-liquid microextraction (HLLME) of organic compounds are generalized and systematized, and a classification of these versions is given. The main HLLME procedures are discussed. Examples of the application of HLLME to the separation of organic compounds in the analysis of environmental samples, food products, and biological fluids are given., Author(s): S. G. Dmitrienko [sup.1], V. V. Apyari [sup.1], M. V. Gorbunova [sup.1], V. V. Tolmacheva [sup.1], Yu. A. Zolotov [sup.1] [sup.2] Author Affiliations: (1) grid.14476.30, 0000 0001 2342 9668, [...]

Dispersive liquid-liquid microextraction (DLLME) is one of the most promising methods of the microextraction preconcentration of organic compounds. This method is eco-friendly, simple, and universal; in comparison with conventional extraction, the consumption of the reagents and solvents, the time of extraction, and the cost of analysis in this method are reduced. For a short time from the moment of the appearance of DLLME in 2006, analysts developed numerous versions, differing by the method of dispersion, the nature of the extractant and by combinations with other methods of sample preparation and methods of the subsequent determination of the preconcentrated substances. The popularity of the method among the analysts is attested in a great number of reviews summarized in this publication., Author(s): S. G. Dmitrienko [sup.1], V. V. Apyari [sup.1], V. V. Tolmacheva [sup.1], M. V. Gorbunova [sup.1] Author Affiliations: (1) grid.14476.30, 0000 0001 2342 9668, Department of Chemistry, Lomonosov Moscow [...]

The use of hypercrosslinked polystyrene for the group sorption preconcentration of catecholamines is proposed. The conditions for the preconcentration of noradrenaline, adrenaline, and dopamine are optimized: a microcolumn (10 x 6 mm), mass of adsorbent 0.03 g, 25 mL of solution (pH ~ 8.5), and transmission rate of the solution 1.0 mL/min. Compounds were desorbed with 1 mL of 6 M acetic acid and determined in the eluate by reversed-phase HPLC with an amperometric detector (E = 0.8 V). Adsorption preconcentration ensures the reduction of the limits of detection for catecholamines by more than 20 times. The limits of detection were 0.7 ng/mL for dopamine and 1 ng/mL for noradrenaline and adrenaline. The procedure was applied to the analysis of model mixtures based on urine., Author(s): V. V. Tolmacheva [sup.1] [sup.2], D. I. Yarykin [sup.1], M. V. Gorbunova [sup.1], V. V. Apyari [sup.1], S. G. Dmitrienko [sup.1], Yu. A. Zolotov [sup.1] [sup.2] Author Affiliations: (1) [...]

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 °C, 0.5М НСl, 20 min) to liberate matrix-bound residues of nitrofurans. Magnetic hypercrosslinked polystyrene (HCP/Fe 3 O 4 ) 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 μg 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 inter-day precision analyses (RSD) are less than 16%. This methodology was applied to real honey samples and trace levels of some veterinary drugs were detected., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Objective: To assess the clinical efficacy and safety of Mexidol in patients in acute period of ishemic stroke in the vertebral-basilar system (iiVBS)., Material and Methods: An open randomized comparative study involved 52 patients. 32 of them received Mexidol (mail group, MG) and 20 received therapy without neuroprotective drugs. Assessment of the severity of clinical manifestations of iiVBS was performed using the Hoffenberth scale, stroke severity was assessed using the NIHSS, the modified Rankin Scale was used to assess the degree of disability in patients after stroke, neuropsychological examination of patients was performed using the Montreal Cognitive Assessment (MoCA), dynamics were compared on the Hospital Anxiety and Depression Scale (HADS), Subjective assessment scale for asthenia (MFI-20), the patients' quality of life was assessed using the EQ-5D., Results: The use of Mexidol in the form of long-term sequential therapy in the patients of the MG led to a 53.3% decrease in the severity of clinical manifestations of iiVBS and a 59.5% decrease in neurological deficit according to the NIHSS scale. By the end of Mexidol therapy, 96.9% of patients MG were able to manage their own affairs without assistance (modified Rankin Scale), which was accompanied by regression of emotional disturbances and improved quality of life of patients., Conclusion: Administration of Mexidol in therapy of patients with acute iiVBS can be considered the most justified, since it contributes to an earlier and more significant reduction of neurological deficit and improvement of patients' quality of life.

A quantitative multi-class multi-residue analytical method was developed for the determination of veterinary drugs in milk by high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS). A total of 132 veterinary drugs investigated belonged to almost 15 classes including sulfonamides, β-lactams, tetracyclines, quinolones, macrolides, nitrofurans, nitroimidazoles, phenicols, lincosamides, pleuromutilins, macrocyclic lactones, quinoxaline antibiotics, benzimidazoles, anthelmintics, coccidiostats and some others. A magnetic solid-phase extraction procedure was developed using magnetic hypercrosslinked polystyrene (HCP/Fe 3 O 4 ) for the sample preparation prior to HPLC-MS/MS without deproteinization step. The results indicated recoveries of 85-107% for 14 sulfonamides, 85-120% for 13 β-lactams, 89-115% for 4 tetracyclines, 82-119% for 14 quinolones, 82-115% for 8 macrolides, 97-109% for 4 nitrofurans, 84-115% for 10 nitroimidazoles, 89-114% for 3 phenicols, 86-111% for 3 lincosamides, 97-102% for 2 pleuromutilins, 72-88% for 4 macrocyclic lactones, 87-104% for 4 quinoxaline antibiotics, 76-119% for 21 benzimidazoles, 79-115% for 12 anthelmintics, 81-118% for 12 coccidiostats and 75-119 % for 5 unclassified drugs, with relative standard deviations (RSDs) of less than 20%, and the LOQs ranged from 0.05 to 1 μg kg -1 . This methodology was then applied to field-collected real milk samples and trace levels of some veterinary drugs were detected., (Copyright © 2022 Elsevier Ltd. All rights reserved.)