Journal of Analytical Chemistry最新文献

A simple, rapid, and highly sensitive method for the simultaneous determination of the main components of Rhodiola rosea (rosin, salidroside, rosarin, and rosavin) in a wide concentration range by hydrophilic chromatography–tandem mass spectrometry is developed. The conditions for the extraction (extractant type and composition, extraction time) of the main components from Rhodiola rosea root samples, chromatographic separation and detection of these compounds are selected, and the performance characteristics of the proposed approach are evaluated. The limits of detection are 250, 2.4, 2.3, and 5.4 ng/mL, and the linearity ranges are 1–100, 0.01–10, 0.01–10, and 0.01–100 μg/mL for rosin, salidroside, rosarin and rosavin, respectively. The developed approach is tested in an analysis of real samples of the pharmaceutical product and of plant raw material.

A new synthetic sorbent (S₁) was obtained based on a copolymer of styrene with maleic anhydride and norsulfazole (S) with subsequent modification by the reagent 4,4'-(ethane-1,2-diylbis(azanylidene))bis(pentan-2-one). The structure of the sorbent S was studied by IR and UV spectrometry. The sorption of Ag(I) ions on the sorbents S and S₁ was studied. The influence of various parameters on the sorption process was studied, i.e., pH, contact time, and initial concentration of the metal ion. The results of the conducted studies were presented by various models of adsorption isotherms and kinetic models. According to the results of the studies, sorption is best characterized by the Langmuir model and the pseudo-second-order kinetic model. The maximum static sorption capacity was 420.08 mg/g for sorbent S and 577.24 mg/g for sorbent S₁. For adsorption studies, a solution of Ag(I) of a concentration of 2 × 10^–3 M was used in the work. Static sorption studies were carried out at room temperature. At the final stage, the process of the desorption of the absorbed silver ions was carried out. For this purpose, mineral (HNO₃) and organic (CH₃COOH) acids were used in the concentration range 0.5–2.0 M. Synthetic sorbents S and S₁ were used to extract silver(I) from mushrooms. The results have shown that the modification of the chelating adsorbent with the reagent 4,4'-(ethane-1,2-diylbis(azanylidene))bis(pentan-2-one) was accompanied by an increase in the sorption capacity, i.e., a simultaneous increase in the efficiency of Ag(I) ion extraction by the obtained synthetic sorption material. Comparative characteristics of the maximum adsorption capacities q_max of various adsorbents with respect to Ag(I) showed that the adsorbents S and S₁ have higher sorption capacity.

This study describes a procedure for optimizing the following parameters: scanning rate, the duration of selective transition registration (dwell time), and the delay between transitions from one selective transition to another (pause time). The study employed a liquid chromatograph coupled with a triple quadrupole mass spectrometric detector (LC–MS/MS Shimadzu 8050). Chromatographic separation was carried out on a Phenomenex Kinetex C18 reversed-phase column. Mobile phase A consisted of a 0.1% solution of formic acid in water with an addition of 10 mmol/L ammonium formate. Mobile phase B consisted of a 0.1% solution of formic acid in methanol with an addition of 10 mmol/L ammonium formate. The optimal parameters for confirmatory methods were determined: the dwell time of the selective transition was at least 10 ms, the pause time between the transitions was 1 ms, and the scanning rate ranged from 1000 to 5000 scans per second. This procedure was successfully applied to routine chemical-toxicological studies of urine samples with low concentrations of various narcotic and pharmaceutical substances.

In this work, a reversed-phase high-performance liquid chromatography method is reported for the determination of methotrexate (MTX), an anticancer drug. The method was found to be simple, sensitive, accurate, and precise. It was validated for the determination of the drug in human serum samples. For this purpose, spiking of the drug and internal standard (IS) was performed in drug-free plasma to assess the method’s applicability. p-Aminoacetophenone was employed as an IS. Protein precipitation was carried out using 2 M trichloroacetic acid, followed by centrifugation. MTX and IS were isolated using a C18 analytical column. The interference of the method was evaluated using blank plasma from six different subjects, and no interference was observed. The method demonstrated a linear response in the range of 300–20 000 ng/mL, with limits of detection and quantification of 1.82 and 6.07 ng/mL, respectively. The method was validated according to FDA and ICH guidelines Q2(R2), with intra- and inter-day accuracy and precision values within allowable limits. Using this method, ≥50% recovery of the drug was achieved from human blood plasma.

MDMB-4en-PINACA is a new synthetic psychoactive compound that has been widely distributed in Russia since at least 2020 and has high activity against the human cannabinoid receptor CB1. Its distinctive feature is the presence of an N-pentene residue, which is rare for this group of compounds. The significant hydrophobicity of MDMB-4en-PINACA, like most other synthetic cannabimimetics distributed on the world markets, causes almost complete biotransformation of the original compound and its extremely low content in urine. Hence, it follows that its metabolites should be identified, the detection of which would indicate the use of MDMB-4en-PINACA. To solve this problem, gas and liquid chromatography–mass spectrometry analysis was used, including high-performance chromatography–mass spectrometry with a quadrupole time-of-flight detector and a three-dimensional ion trap detector equipped with an electrospray ionization source. A number of putative metabolites of MDMB-4en-PINACA were detected in human urine, which were identified as products of hydrolysis, mono- and dihydroxylation, reduction, dihydrodiol formation, carboxylation, carboxylation with elimination of the methylene group, N-dealkylation, and combinations of these processes. A number of metabolites were found in the form of glucuronides. The results obtained are in good agreement with published data. The search for the products of hydrolysis, dihydroxylation, and dihydrodiol formation is optimal for routine chemical toxicological and forensic chemical analysis of urine by gas chromatography-mass spectrometry, while it is also recommended to detect glucuronides of hydrolysis products and dihydrodiol formation with the use of liquid chromatography–mass spectrometry.

Short-chain fatty acids (SCFAs), produced by the gut microbiota, play a crucial role in maintaining the immune status of a body. Chronic kidney diseases are associated with a reduction in microbial diversity in the gut and a disruption in SCFA production. In chronic kidney diseases, the level of SCFAs in the circulating blood decreases; so, the development of highly sensitive methods for determining SCFAs in serum is necessary. We have developed a method for determining SCFAs in serum and tested it in a comparative study of serum samples from healthy volunteers and patients with diagnosed chronic kidney diseases. The determination of SCFAs (acetic, propionic, butyric, valeric, caproic, iso-butyric, and iso-valeric acids) in blood serum was carried out by gas chromatography–mass spectrometry (GC–MS) and gas chromatography–tandem mass spectrometry (GC–MS/MS). The limits of detection for the investigated SCFAs by GC–MS range from 0.05 to 0.09 µg/mL, while the limits of detection by GC–MS/MS range from 0.002 to 0.007 µg/mL. In the serum samples of patients with chronic kidney diseases, the concentrations of all the investigated SCFAs were lower compared to the control group and fell below the limits of detection of the GC–MS method.

This paper describes a two-step algorithm for detecting muscarine, ibotenic acid, and muscimol in urine samples. A two-step procedure was developed for detecting muscarine, muscimol, and ibotenic acid using a data-dependent mode of MRM analysis with the simultaneous full mass spectrum recording of the target substances. Analytes were detected by HPLC coupled with a triple quadrupole mass spectrometric detector (LC–MS/MS Shimadzu 8050). Chromatographic separation was performed in a Phenomenex Kinetex C18 reversed-phase column. At the first step, muscarine was detected in a diluted urine sample. At the second step, muscimol and ibotenic acid were found using a bimolecular dansylation method. The procedure has been successfully applied to routine chemical and toxicological analyses of urine samples from patients suspected of mushroom poisoning.

The list of regulated contaminants for the food safety ensurance is very extensive: drugs (antibiotics, non-steroidal anti-inflammatory drugs, coccidiostatics, antithyroid drugs, β-adrenergic stimulants, anthelmintic agents, etc.), pesticides, toxic elements, hormones, polychlorinated biphenyls, dioxins, natural toxins (zoo-, phyto-, and mycotoxins, toxins of bacterial origin, and biogenic amines), etc. Laboratory control is the main means of determining contaminants in food raw materials and food products when establishing their compliance with hygienic standards. Mass spectrometry has been the most effective tool for laboratory control both in Russia and abroad for over 20 years. This review considers the procedures developed by the Federal State Budgetary Institution “The Russian State Center for Animal Feed and Drug Standardization and Quality” (FGBU “VGNKI”) with the use of mass spectrometry; these procedures are of greatest interest from the point of view of implementing food safety monitoring in the Russian Federation. Promising areas of research work are also considered taking into account the main problems and achievements in the field of mass spectrometry.

The antibiotics ceftriaxone and cefotaxime, both in their pure forms and in pharmaceutical formulations, were determined spectrophotometrically using tartrazine dye. The method is based on the bromination of these drugs by a known excess of N-bromosuccinimide (NBS) in an acidic medium. The remaining NBS bleaches the lemon-yellow azo dye color of tartrazine, which was measured at 426 nm. The decolorization of the dye is proportional to the residual amount of NBS, which is, in turn, proportional to the concentration of the drugs. Lineovery percentages of 100.13 and 99.18%, molar absorptivity values of 1.07 × 10⁵ and 8.2 × 10⁴ L/(mol cm), and relative standard deviation of ≤1.789% for ceftriaxone and cefotaxime, respectively. The method is sensitive, simple, precise, accurate, and free from excipients. The developed method was successfully applied to determine these drugs in their pharmaceutical formulations, and the reaction mechanism was proposed.