As a result of the assessment of the thermal stability of components of essential oils of Mentha piperita, Lavandula angustifolia, and a linalool sample, it is shown that most of them are sufficiently stable under the conditions of gas-chromatographic analysis at injector temperatures up to 300°C. The assessments were performed using an algorithm involving sigmoidal approximation (otherwise, logistic regression) of the dependences of the relative peak areas on the injector temperature. A slight decrease in amount was detected only for the γ-terpineol impurity in the linalool preparation. In addition, an increase in the γ-terpinene content was recorded as a result of the thermal decomposition of other components. Unexpectedly interesting results were obtained for the essential oil of Lavandula angustifolia, in which significant amounts of a low-volatile matrix—low-molecular polyethylene glycols—were found. This proves useful in revealing an important feature of the algorithm itself for characterizing the thermal stability of analytes. It was shown that an increase in the relative areas of chromatographic peaks with increasing injector temperature can be not only due to the formation of thermal decomposition products of unstable precursors, but also due to the presence of non-volatile or low-volatile matrix components in the samples. A sign of such an anomaly is provided by the ascending dependences of the peak areas of all components in the absence of analytes with descending dependences.

Oxidative stress occurs due to an imbalance between the production of reactive oxygen and nitrogen species and the body’s antioxidant defenses, resulting in molecular and cellular damage associated with many diseases. This review systematically examines oxidative stress biomarkers, their molecular foundations, detection techniques, and novel advances that enhance the clinical and research applications of redox biology evaluations, thereby advancing precision medicine in oxidative stress disorders. The biochemical foundation and clinical significance of critical markers are investigated, including malondialdehyde, 4-hydroxynonenal, protein carbonyls, 8-hydroxydeoxyguanosine, and antioxidant enzymes, as well as advancements in detection methodologies such as chromatography, mass spectrometry, immunoassays, electron spin resonance, and novel biosensor technologies. Moreover, omics-based multi-marker panels and integrated analytical methods provide improved sensitivity, specificity, and mechanistic understanding, facilitating the advancement of precision medicine applications. Challenges such as biomarker specificity, stability, and standardization are examined, with future outlooks emphasizing the potential of modern technologies to enhance oxidative stress evaluation for disease diagnosis, prognosis, and therapy monitoring.

As an antibiotic, tetracycline (TC) is widely used and plays an important role in anti-infection treatment, so the quantitative detection of TC is of great significance. The purpose of this research is to develop a novel synthesis of silver nanoclusters stabilized with non-thiol small molecules and their application in the detection of tetracycline. Silver nanoclusters (AgNCs) were synthesized under optimized conditions using Acid Red 94 as a stabilizer, silver nitrate solution as the raw material, and sodium borohydride as the reducing agent. The optimal excitation wavelength of the synthesized AgNCs was 330 nm, and the optimal emission wavelength was 435 nm. It was found that TC could significantly quench the fluorescence of the synthesized AgNCs. The quenching value (ΔF) of the fluorescence intensity of the AgNCs has a good linear relationship with the TC concentration in the range of 10.0–50.0 μmol/L, and the detection limit was 2.3 μmol/L. Therefore, a method for TC detection was established, which was further verified by the spiked recovery method in water samples. The spiked recovery rate ranged from 101.7 to 103.8%, indicating that the established method has potential application value for the quantitative detection of TC in water samples. Additionally, a visual quantitative detection method for TC was achieved based on smartphone and colorimetric analysis software using AgNCs as fluorescent probes.

The formation of positive and negative ions in the homologous series of trinitrobenzene, trinitrotoluene, and trinitroxylene was studied by mass spectrometry. Positive and negative ion mass spectra were acquired through electron ionization and resonant electron capture methods on a quadrupole mass spectrometer within a GC–MS system. The ionic compositions of the opposite-sign spectra display both similarities and complementary differences that aid in compound identification. These features are interpreted through quantum chemical calculations of the thermal effects associated with molecular ion fragmentation. For trinitrobenzene, close correspondence between the composition of positive and negative ion peaks in the spectra reflects comparable energy requirements for nitro group elimination via the simple C–N bond cleavage and the nearly equal exothermicity of NO release through the nitro–nitrite rearrangement. In contrast, the methyl-substituted compounds, trinitrotoluene and trinitroxylene, exhibit pronounced differences: their positive ion spectra are dominated by products of multistage decays initiated by the exothermically favorable release of a hydroxyl group due to the ortho effect, whereas the analogous processes in negative ions demand additional energy input. The observed abundance of exothermic fragmentation pathways provides insight into the relative stability of molecular ions and suggests parallels with the mechanisms of explosive transformations.

The paper presents procedures for the direct analysis of table wines by microwave induced plasma optical emission spectrometry (MIP OES) and inductively coupled plasma optical emission spectrometry (ICP OES) using matrix matched reference standards. K, Na, Ca, Mg, B, Si, Al, Fe, Cu, Mn, Ba, Sr, Li, and Zn are quantified from a single dilution with an relative standard deviation of no more than 10% (n = 2). The range of constant analytical signals upon varying the concentrations of potassium, alcohol, and sucrose during an MIP OES analysis is determined. No reduction in the background signal is demonstrated upon replacing nitrogen with air in the intermediate gas flow, and improved analytical performance is demonstrated using yttrium as an internal standard in MIP OES. The results are confirmed by capillary zone electrophoresis, spike experiments, and a comparison of the results of ICP OES and MIP OES analyses.

The features of planar (thin-layer) chromatography of several linear non-ionic polysaccharides (amylose, pullulan), their visualization by post-chromatographic derivatization with iodine, and the factors influencing this process are described. It is shown that the coloration of pullulan results from the formation of pseudoclathrate complexes of molecular iodine–iodide–pullulan in short helical segments of the polysaccharide, as well as iodine absorption in the bends of the polymer chain. It was established that the shift of the spectral absorption maximum of amylose (λmax ~ 600 nm, blue coloration) to the shorter wavelength region (λmax = 560 nm, red-brown coloration) is associated with specific interactions of starch with silica and the formation of a molecular iodine–iodide–anion–amylose–silica gel complex. It was demonstrated that the intensity of iodine staining of high-molecular-weight polysaccharides does not depend on their degree of polymerization, and polysaccharide visualization by the iodine reaction in thin-layer chromatography is possible only on neutral forms of silica sorbent.

Medicinal plants are a valuable source of biologically active substances used to prevent and treat diverse diseases. The major classes of these compounds—alkaloids, glycosides, flavonoids, essential oils, tannins, polyphenols, and polysaccharides—exhibit broad pharmacological activities, including antimicrobial, anti-inflammatory, antiseptic, and antioxidant effects. Phytochemical screening of plant extracts plays a crucial role in identifying these compounds and supporting the development of new therapeutic agents. In this study, a spectrophotometric phytochemical screening was performed to evaluate alkaloids, tannins, flavonoids, phenolic compounds, steroid cardiac glycosides, and polysaccharides and the antioxidant activity of extracts from three medicinal plants from different families, milk-ripened oats (Avena sativa L.), madder root (Rubia tinctorum L.), and Scotch heather (Calluna vulgaris L.), was assessed. High-performance liquid chromatography was used to achieve a more detailed chemical profile. Both conventional solvents (methanol, ethanol, water-alcohol mixtures, water, acetonitrile) and a new class of solvents, deep eutectic solvents, were used as extractants. Ultrasound-assisted extraction proceeded at 40–80°C for 10–60 min. The optimal extraction conditions were found for the major compound groups: 80°C for 60 min with conventional solvents, 50°C for 30 min for Calluna vulgaris L. with deep eutectic solvents, and 60°C for 30 min for madder root and oats with deep eutectic solvents. The results demonstrate that deep eutectic solvents effectively extract the target bioactive substances under milder conditions, underscoring their potential as environmentally sustainable extractants in phytochemical research.

Procedures for the determination of 53 impurities, including rare earth elements, in boric acid by inductively coupled plasma optical emission spectrometry (ICP–OES) have been developed. To optimize analysis conditions, the variation of impurity element signals was studied at boron concentrations ranging from 0 to 5000 mg/L and plasma powers of 1000, 1300, and 1600 W under axial observation. Most impurity elements exhibited the maximum analytical signals at the highest plasma power and at the highest boron concentration in the test solution. Taking into account the significant effect of the matrix on impurity element signals starting from approximately 500 mg/L of the matrix element, calibration curves were constructed using the spike method. The accuracy of the analysis was confirmed by spiking with the analyte elements with recoveries of 85–115%. The limits of detection calculated by the 2s test ranged from n × 10–7 to n × 10–4 wt %.

A new complexing analytical reagent is synthesized by the condensation of salicylic aldehyde with isatin hydrazone. The dissociation constant of the reagent pK = 9.48 ± 0.03 is determined. The structure of the reagent is studied by X-ray diffraction and NMR spectroscopy. The complexation of palladium(II) with [(2-hydroxybenzaldehyde)-3-isatin]-bishydrazone (R) in the presence and absence of diantipyrylmethane (DAM), 8-hydroxyquinoline (8-HQ), and diphenylguanidine (DPG) is studied by spectrophotometry. Optimum conditions for complexation (λopt, pHopt) are selected. It is found that palladium(II) forms colored mixed-ligand complexes with the reagent in the presence of the third component, DAM, 8-HQ, or DPG. The Pd(II)–R complex exhibits the maximum absorbance at the wavelength 440 nm, and the Pd(II)–R–DAM, Pd(II)–R–8-HQ, and Pd(II)–R–DPG complexes, at 465, 490, and 450 nm, respectively. The molar absorption coefficients for Pd(II)–R are 6000 L/(mol cm), and for Pd(II)–R–DAM, Pd(II)–R–8-HQ, and Pd(II)–R–DPG they are 10 000, 8000, and 7500 L/(mol cm), respectively. The optimum pH value for Pd(II)–R is 4, for Pd(II)–R–DAM and Pd(II)–R–DPG it is 2, and for Pd(II)–R–8-HQ it is 3. The stability constants of the complexes are determined. The region of adherence to the Beer law is found. The equations of the calibration graphs are constructed using the least-squares technique. The ratio of components in the composition of homogeneous and mixed-ligand complexes is determined by the methods of isomolar series, continuous variations (Job’s method), and slope. All methods show that the ratio of the Pd(II)–R components in the binary complex is 1 : 2, and in the mixed-ligand complexes Pd(II)–R–8-HQ and Pd(II)–R–DPG – 1 : 1 : 1, Pd(II)–R–DAM – 1 : 2 : 1. The effect of some foreign ions and masking substances on the formation of homogeneous and mixed-ligand complexes of palladium(II) is studied. It is found that Na(I), K(I), Ca(II), Ba(II), Cd(II), Ni(II), Cr (III), Co(II), Pd(IV), platinum-group metals, and many anions do not interfere with the determination of Pd(II). The developed procedure is applied to the determination of trace amounts of palladium(II) in a nickel anode material.