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Vol 80, No 6 (2025)
ORIGINAL ARTICLES
Turmeric identification and adulteration detection by digital colorometry and near-IR spectroscopy methods
Abstract
The possibility to identify and establish the fact of turmeric adulteration by simple and affordable methods using methods of infrared spectroscopy, digital colorometry and chemometric processing of spectral data was shown. Near-infrared spectroscopy was used to differentiate between samples of turmeric powder purchased in India, made by grinding the roots, and commercial samples, and to separate them from samples with impurities of flour, starch, breadcrumb and chalk by analyzing diffuse reflectance spectra using principal component methods, hierarchical cluster analysis and formal independent class analogy modeling. The same approaches were applied to the simpler and less costly colorometric method. Chemometric processing of the obtained data confirmed the lack of similarity of the analyzed turmeric samples with samples containing additives and allowed the determination of impurities using multivariate regression analysis algorithms. Comparison of the results obtained by IR spectroscopy and digital colorometry showed their equivalent efficiency, which allowed us to recommend the more affordable colorometric method for routine quality control and detection of turmeric adulteration.
Journal of Analytical Chemistry. 2025;80(6):533-544
533-544
Increasing the sensitivity of immunochromatographic assay for penicillin determination in milk due to oriented immobilization of penicillin-binding protein on the surface of colloidal gold
Abstract
The sensitivity of competitive immunochromatographic assay (ICA) for the determination of penicillin in milk using colloidal gold (CG) conjugates with recombinant penicillin-binding protein (PBP) prepared by two methods, passive non-oriented immobilization and oriented immobilization with antibodies to the histidine tag, was compared. The detection limit of the optimized ICA with non-oriented PBP immobilization was 5 ng/mL. It was possible to achieve a detection limit of 0.3 ng/mL with visual interpretation due to antibodies to the histidine tag with the use of oriented PBP immobilization. The analysis time was 10 min. The efficiency of two PBP immobilization methods was compared. It was shown that the sensitivity of the assay increased due to an improved PBP orientation and a simultaneous decrease in the number of binding sites on the CG. Thus, targeted immobilization of specific proteins on sensor surfaces using antibodies to the histidine tag can increase the sensitivity of the assay and simultaneously decrease the amount of biospecific reagents used. This approach can be applied to the simple conjugation of recombinant proteins with a histidine tag to nanoparticles.
Journal of Analytical Chemistry. 2025;80(6):545-557
545-557
CHROMATOGRAPHY–MASS SPECTROMETRY OF TRINITROTOLUENE ISOMERS IN THE NEGATIVE IONIZATION MODE UNDER RESONANCE ELECTRON CAPTURE
Abstract
For trinitrotoluene isomers by gas chromatography-mass spectrometry (GC-MS), the processes of chromatographic separation and formation of negative ion (NI) mass spectra in the mode of resonant electron capture, implemented by a minimal technical modification of the domestic serial GC-MS complex “Chromatech-Crystal”, were investigated and compared with the basic mode of positive ions (PI) under electron ionization. The chromatographic retention time of the isomers was found to increase in direct proportion to the dipole moment of the molecules, illustrating the significance of intermolecular dipole interactions between polar molecules of the analyte and the stationary phase. It is shown that the chromatograms of full current OI, which are recorded at fast constant scanning of ionizing electron energy in the low-energy range of 0-10 eV, well reflect the component composition of the analyzed sample, and the integral mass spectra of OI are characteristic and selective to isomers, being complementary in informativeness to the standard mass spectra of PI. This is due to the predominance of nitro-nitrite rearrangements and simple C-NO2bond breaking at negative ionization over H-shift reactions, which dominate in the formation of PIs from TNT isomers.
Journal of Analytical Chemistry. 2025;80(6):558-573
558-573
ION-SELECTIVE ELECTRODE FOR RAPID DETERMINATION OF CEFTRIAXONE IN BIOLOGICAL OBJECTS
Abstract
An ion-selective electrode for the rapid determination of ceftriaxone (Ceftr) in biological objects has been proposed, in which the ionic associate of octadecylamine (ODA) with Ceftr is an electrode-active component (EAC) of the Ceftriaxone-selective electrode (Ceftr-SE) membrane. In order to establish the mechanism of membrane function, the equilibria in the membrane-solution system were studied as a function of the acidity of the medium and the amount of EAC. At pH 6–9, the ionic associate (ODA)2+ -Ceftr2– is stable and the membrane responds selectively to ceftriaxone. The optimal membrane composition for Ceftr-CE, (wt. %) was selected: (ODA)(2)+ -Ceftr(2–) – 0.80, polyvinyl chloride – 33.06, ODA – 1.7 (100 mM), dioctyl sebacinate – 66.14, internal electrolyte Ceftr (0.01 M) + KCl (0.01 M). The electrochemical performance characteristics of the Ceftr-SE membrane were studied: linear range 1 × 10(–5) –0.1 M, steepness of the electrode function 24.9 mV/decade, detection limit of Ceftr 8.3 × 10(–6) M. The potentiometric selectivity coefficients of Ceftr-SE were determined by the method of bi-ionic potentials. The electrode was used for the determination of Ceftr in blood and saliva of covid patients. The correctness of the results of Ceftr determination was confirmed by the injected-found method.
Journal of Analytical Chemistry. 2025;80(6):574-581
574-581
Direct analysis of vegetable oils by atmospheric pressure laser plasma ionization combined with machine learning methods
Abstract
The atmospteric pressure laser plasma ionization (APLPI) method in combination with machine learning methods is investigated to solve the problem of classification of vegetable oils. Samples of olive oil, rapeseed oil, sunflower oil and linseed oil were studied. The samples were classified on the basis of mass spectrometric profiles of volatile organic compounds emitted by the oils. It was shown that when hierarchical cluster analysis (HCA) with pre-selection of features by analysis of variance (ANOVA) and reduction of the dimensionality of the response matrix by t-distributed stochastic neighbor embedding (t-SNE), each type of oil forms a distinct cluster. Using the example of olive and rapeseed oil blends analysis, it was demonstrated that the combination of the APLPI method with the multiple linear regression (MLR) method allows to quantify the share of oils in the studied blends. The developed approach allows for rapid, direct nondestructive analysis of vegetable oils without sample preparation and can be used for detection of adulterated products.
Journal of Analytical Chemistry. 2025;80(6):582-591
582-591
Application of polarization fluorescence immunoassay for the determination of flunixin in milk
Abstract
The technique of polarization fluorescence immunoassay for the detection of residual amounts of nonsteroidal anti-inflammatory drug flunixin used for prophylaxis and treatment in veterinary medicine and animal husbandry was developed. The optimal analysis time was 15 min taking into account sample preparation, the linear range was 20-5000 ng/mL, and the limit of detection was 2 ng/mL. High selectivity of immunoreagents with respect to the antigen under study was shown; cross-reactivity coefficients with preparations having structural similarity to flunixin did not exceed 0.01 %. The method of flunixin determination in milk was tested by the injected-found method, it was shown that the application of the developed method of sample preparation allows effective detection of the investigated antigen within the linear range. These results indicate the possibility of using the developed technique with the use of polyclonal antibodies for express and sensitive determination of flunixin in milk.
Journal of Analytical Chemistry. 2025;80(6):592-603
592-603
Determination of pesticide residues in wheat grain by the GC-MS/MS method after their isolation using the modified Quechers method and hyper cross-linked polystyrene at the purification stage
Abstract
Hyper cross-linked polystyrene was proposed for purification of extracts after sample preparation by QuEChERS method using multicomponent dispersive solid-phase extraction for determination of 19 pesticide residues in wheat grain by gas chromatography with tandem mass spectrometric detection. Sample preparation included extraction with water and acetonitrile and further purification of the extracts using hyper cross-linked polystyrene. The method provided quantitative separation of pesticides (degrees of separation ranged from 66 to 100 %). Pesticides were identified by selected transitions in multiple reaction monitoring mode. Determination was carried out by matrix graduation method and the limits of detection and determination were 0.03–0.3 and 0.1–1.0 µg/kg, respectively. The analysis of contaminated wheat samples showed that the results satisfactorily coincide with the data obtained by the classical QuEChERS method for determination of pesticide residues in agricultural products.
Journal of Analytical Chemistry. 2025;80(6):604-615
604-615
Errors and errors of instrumental research in determining the age of execution of details in documents by the relative content of volatile solvents in the strokes
Abstract
The paper considers the issues related to the influence of measurement error on expert errors in determining the age of execution of details in documents by the relative content of volatile solvents in the strokes. The influence of the relative standard deviation value for the output signal of 2-phenoxyethanol on the reliability of the obtained results is shown. A graphical relationship between the standard deviation and the mean value of the 2-phenoxyethanol output signal is given. Examples of erroneous data in expert conclusions are given.
Journal of Analytical Chemistry. 2025;80(6):616-623
616-623
ИСТОРИЯ АНАЛИТИЧЕСКОЙ ХИМИИ
THE DISCOVERY OF CHROMATOGRAPHY AND THE IMPERIAL ST. PETERSBURG ACADEMY OF SCIENCES
Abstract
The article reveals the role of the Laboratory of Plant Anatomy and Physiology of the Academy of Sciences created by Academician A.S. Famintsyn in the birth and development of the idea of the chromatographic method of analysis by M.S. Tsvet in 1897– 1901. On the basis of previously unknown documentary and other materials it is established that M.S. Tsvet in fact discovered chromatography in 1901, and not in 1903, as it is commonly believed, and not in Warsaw, but in St. Petersburg, and in many respects thanks to the assistance of the academic community and first of all academician A.S. Famintsyn. The data on the establishment and activities of the Laboratory, on the life and creative pursuits of M.S. Tsvet in St. Petersburg, on his communication with colleagues and on the attitude of the Academy of Sciences staff to his works are presented.
Journal of Analytical Chemistry. 2025;80(6):624-636
624-636
EVENTS
К юбилею профессора х. з. Брайниной
Journal of Analytical Chemistry. 2025;80(6):637-637
637-637
КОНЧИНА ИРИНЫ РУДОЛЬФОВНЫ ШЕЛПАКОВОЙ
Journal of Analytical Chemistry. 2025;80(6):638-638
638-638