Quantitative Determination Research Articles

Multi-omics analysis provides insights into the mechanism underlying fruit color formation in Capsicum

Fruit color is a crucial attribute of fruit quality in peppers (Capsicum spp.). However, few studies have focused on the mechanism of color formation in immature pepper fruits. In this study, the light-yellow color observed in immature CSJ009 fruits compared to CSJ010 could be attributed to decreased chlorophyll and carotenoid pigments. Through integrated analysis of the transcriptome and metabolome of CSJ009 and CSJ010, we identified 23,930 differentially expressed genes (DEGs) and 345 differentially accumulated metabolites (DAMs). Furthermore, integrated analysis revealed a strong correlation between the HCT-like gene and metabolite MWS0178 (chlorogenic acid). Paraffin section assay revealed that the epidermal cells of immature CSJ010 fruits exhibited a more compact arrangement with significantly greater length than those of CSJ009. Quantitative determination of carotenoids showed that lutein emerged as the predominant carotenoid in immature pepper fruits. Additionally, missense mutation of LCYB2 is likely to lead to a decrease in β-carotene content in immature CSJ009 fruits, whereas CCS may directly catalyze the conversion of lycopene to β-carotene in mature fruits. The null mutation in CCS promoted the biosynthesis of β,ϵ-branch carotenoids leading to lutein being the most abundant carotenoid found in orange CSJ010 fruits. These findings provide important insights into the mechanism underlying color formation in pepper fruits and establish a foundation for the further exploration of color-related genes.

Extraction of methamphetamine and pseudoephedrine by modified graphene oxide solid phase extraction method coupled to HPLC-UV in urine sample.

Methamphetamine, pseudoephedrine, and related drugs are among the first drugs used for the stimulation of the central nervous system. In this study, two adsorbents based on graphene oxide (GO) were synthesized and used for the analysis of methamphetamine and pseudoephedrine. The prepared nano-adsorbents based on GO in this study were coated by polyaniline (PANI) and Fe3O4/C-nanodot/GO (magnetic adsorbent). The average size of nanoparticles (GO/PANI) was 18.43nm. The specific surface area and pore size diameter of Fe3O4/C-nanodot/GO were 22.71 m2 g- 1 and 15.23nm, respectively. Experimental variables affecting the extraction efficiency of the analytes such as pH of the sample solution, amount of adsorbent, extraction time, and type of eluents were investigated and optimized by response surface methodology. Under optimum conditions, GO/PANI and Fe3O4/C-nanodot/GO were considered appropriate solid phase extraction adsorbents for HPLC-based analyses of the studied drugs in human urine samples. However, GO/Fe3O4 nano adsorbent (Fe3O4/C-nanodot/GO) showed superior working condition than GO/PANI. The validated proposed analytical methods can be used for the quantitative determination of methamphetamine and pseudoephedrine in actual samples.

Quantitative analysis of wool and cashmere fiber mixtures using NIR spectroscopy

Abstract The quantitative determination of wool and cashmere mixed fiber is an indispensable quality control link in the textile industry, crucial for improving international trade status, ensuring product quality, and safeguarding consumer rights. Therefore, the goal of this study is to develop a reliable method for estimating fiber contents in wool–cashmere blends based on near-infrared (NIR) spectroscopy. A total of 210 mixed samples of 21 different proportions of cashmere and wool are prepared in the experiment, and data are collected in the NIR spectral band of 1,000–2,500 nm. Convolution Savitzky–Golay (S–G) combined with the second-order derivative is then used for spectral preprocessing. The variable iterative space shrinkage approach (VISSA) optimizes the characteristic wavelengths, and 339 wavelength points are selected. The prediction model of the least squares support vector machine (LSSVM) is established by particle swarm optimization (PSO), fast positioning, and analysis of key information related to the target in complex spectral data. Finally, the training set and the prediction set are divided according to the ratio of 8 : 2. Experiments show that in terms of modeling and prediction, the PSO-LSSVM model based on the wavelength selected by VISSA has a prediction determination coefficient R-squared of 0.9821, a prediction root mean square error of 1.1263, and an mean absolute error of 0.6527. The hybrid modeling method of VISSA, PSO, and LSSVM based on NIR spectroscopy (VISSA–PSO–LSSVM) can provide a more accurate and stable method for the non-destructive detection of cashmere and wool blended fiber content.

Construction and Application of Au NRs/4-MBA/PAM Ratiometric Surface-Enhanced Raman Scattering Substrate for Fish Veterinary Drug Residue Detection

Surface-enhanced Raman scattering (SERS) is widely used for trace detection of substances, and the key to this technology lies in the preparation of the substrate material. In this study, a composite SERS material of Au NRs/4-MBA/PAM was constructed and characterized to better immobilize the reference molecule 4-mercaptobenzoic acid (4-MBA). Electron transmission microscopy results demonstrated that the PAM film helps Au NRs to pack closely, enhancing the stability of the material structure and reducing the interference of external environmental factors on the response of 4-MBA, thus improving the accuracy of quantitative determination. Comparative experimental results with the Au NRs/4-MBA substrate showed that the relative standard deviations (RSDs) of the detection results for MG on different batches of Au NRs/4-MBA/PAM were less than 8.0%, and the RSDs of different points on the same material were less than 10.0%, indicating that the Au NRs/4-MBA/PAM has higher uniformity, better reproducibility, and higher sensitivity in detecting malachite green (MG). Applying this material in the recovery determination of fish extract showed that the recovery rates of MG were between 75.60% and 83.24%. Therefore, the Au NRs/4-MBA/PAM substrate can accurately detect and quantify veterinary drug residue in complex matrices such as food tissue.

Quantitative determination of tannins by titrimetry and spectrophotometry in raw materials of some representatives of the genus Rumex of three growing seasons

Introduction. Study of the chemical composition of medicinal plant raw materials and comparative analysis of the dynamics of accumulation of biologically active substances in related medicinal plants is necessary for the creation of highly effective and safe drugs. Similar metabolome to the officinal representative of the genus Rumex (hereinafter referred to as R.) – R. confertus – the metabolome of species widely distributed in Russia: R. crispus, R. obtusifolius, R. aquaticus, which determines the perspectivity of studying these species. Scientific and practical interest is represented by the study of the group of biologically active substances possessing antibacterial activity – tannins at different phenological stages of plant development.Aim. Quantitative determination of tannins by permanganatometry and spectrophotometry methods in underground organs of R. confertus, R. crispus, R. obtusifolius, R. aquaticus, harvested in different phases of vegetation: regrowth, flowering and withering periods.Materials and methods. Aqueous extracts from underground organs of the studied Rumex species were analyzed. Extractions and solutions obtained during the study were analyzed by permanganatometry, spectrophotometry and HPLC. The compounds from the group of tannins were identified by the wavelength of absorption maximum.Results and discussion. The quantitative content of tannins was evaluated by permanganatometry, spectrophotometry and HPLC.Conclusion. Tannins were detected and quantified in extracts from underground organs of R. confertus, R. crispus, R. obtusifolius, R. aquaticus and the dependence between their quantitative content and vegetation phase was analyzed.

Absolute Quantification of Phenylbutanoids in Zingiber cassumunar Roxb. Rhizome by Quantitative 1H NMR.

Quantitative determination of pharmacologically active constituents in medicinal plants is critical for quality control. Due to the chemical complexity of the crude plant extracts, the presence of interfering compounds is often problematic for the unambiguous quantitation of the designed bioactive compounds. Considering the method of quantification, quantitative NMR spectroscopy (qNMR) has gained substantial popularity as a powerful and effective technique for both qualitative and quantitative analyses of natural products. The aim of this study is to develop a quantitative NMR method for quantifying the bioactive phenylbutanoids in Zingiber cassumunar rhizome crude extract. Quantitative 1H NMR (qHNMR) measurements were performed on a 600 MHz NMR spectrometer using an internal standard for the determination of the absolute quantities of four phenylbutanoids in Z. cassumunar rhizome crude extract. The direct quantification of four characteristic phenylbutanoids, i.e., (E)-1-(3',4'-dimethoxyphenyl)butadiene (DMPBD), (E)-1-(2',4',5'-trimethoxyphenyl)butadiene (TMPBD), (E)-4-(3',4'-dimethoxyphenyl)but-3-en-1-ol, and (E)-4-(3',4'-dimethoxyphenyl)but-3-en-1-yl acetate, in crude extract by qHNMR using an internal standard was achieved, with high specificity and sensitivity. The selected 1H NMR signals could unambiguously be assigned and did not overlap with other resonances, including the highly similar compounds DMPBD and TMPBD. The method is linear in the concentration range of 0.70-14.52 mg/mL, with a limit of quantification of 0.46-0.68 mg/mL. The RSD values of intraday and interday precisions are in the range of 0.23%-0.74% and 0.29%-0.52%, respectively. The average recoveries are 99.54%-100.18%. A rapid, accurate, and precise method using 1H NMR for the simultaneous quantitation of four phenylbutanoids in the crude extract of Z. cassumunar rhizome was developed and validated.

Kinetic Bacterial Endotoxin Testing Methods: Specifics of Analytical Conditions Exemplified by Medicinal Products from Different Classes

INTRODUCTION. Kinetic bacterial endotoxin (BE) testing methods based on amoebocyte lysate from the haemolymph of the horseshoe crab can quantify BEs in parenteral medicinal products across a broad range of concentrations. To develop a specific analytical procedure that is based on these methods and can be implemented into pharmaceutical quality control and standardisation, it is required to ascertain the conditions for its use, in particular, to determine the lowest product dilution that would neutralise interfering factors.AIM. This study aimed to develop an analytical procedure for the quantitative determination of BEs by the kinetic chromogenic method.MATERIALS AND METHODS. The study examined samples of medicinal products containing active substances from different classes, including a monoclonal antibody (mepolizumab) and a direct-acting anticoagulant (nadroparin). The BE limits for mepolizumab and nadroparin were ≤20 EU/mL and ≤95 EU/mL, respectively. The samples were tested at different dilutions, which did not exceed the maximum valid dilution. The measurements were performed using a BioТek EL×800 photocolourimeter and EndoScan-V software.RESULTS. The results for mepolizumab samples show that the kinetic chromogenic method can quantify BEs in mepolizumab medicinal products in the dilution range of 1:10 to 1:40. The study detected BEs in quantities of 0.0078–0.224 EU/mL within this dilution range. However, at a dilution ratio of 1:50 or higher, the method is suitable only for qualitative BE tests. For nadroparin medicinal products, the quantitative determination of BEs should start at a dilution of 1:1000 (the study demonstrated no influence of interfering factors at this dilution).CONCLUSIONS. The authors developed analytical procedures for the determination of BEs in mepolizumab and nadroparin medicinal products by the kinetic chromogenic method (method D). When developing analytical procedures for the quantification of BEs in individual medicinal products, the developer should determine the lowest sample dilution that would neutralise interfering factors. Subsequently, the dilution should be specified in the documentation for the analytical procedure. This approach can enhance assay accuracy and save time and resources in routine testing.

Development and Validation of an Analytical Procedure for Determining Convallatoxin in Medicinal Products Containing Cardiac Glycosides of Lily of the Valley

INTRODUCTION. The safe use of lily-of-the-valley medicinal products requires adequately controlling the content of cardiac glycosides. The State Pharmacopoeia of the Russian Federation stipulates that the content of cardiac glycosides in lily-of-the-valley medicinal products should be quantified using bioassays and spectrophotometry. However, the determination of cardiac glycosides needs more accurate and selective physicochemical methods, such as high-performance liquid chromatography (HPLC).AIM. This study aimed to develop and validate an HPLC analytical procedure for the quantitative determination of cardiac glycosides (convallatoxin) in lily-of-the-valley herbal medicinal products.MATERIALS AND METHODS. The study examined the Lily-of-the-Valley Tincture, Zelenin Drops, Valocormid, Carniland®, and Lily-of-the-Valley Extract Reference Standard samples. The content of cardiac glycosides was determined by comparison with a reference standard for convallatoxin by HPLC and spectrophotometry. The samples were prepared as outlined in Monograph 3.4.0003.18 Lily-of-the-Valley Herb Tincture of the State Pharmacopoeia of the Russian Federation. Mixed cardiac glycosides were separated on a Luna 5 µm C18(2) column by gradient elution with 0.1% orthophosphoric acid in water and acetonitrile. The analysis was performed using an autoinjector with sample cooling to 5 °C.RESULTS. The developed analytical procedure met the acceptance criteria for specificity, intermediate precision, linearity (correlation coefficient of 0.99985), and repeatability (relative standard deviation of convallatoxin measurements of 1.61%). The analytical procedure is suitable for the quantitative determination of convallatoxin in lily-of-the-valley herbal medicinal products because it produces reliable and repeatable results.CONCLUSIONS. The authors developed a highly sensitive and selective HPLC analytical procedure for the quantitative determination of convallatoxin in lily-of-the-valley herbal medicinal products. The content of convallatoxin ranged from 0.012 to 0.018 mg/mL in the liquid active substance Lily-of-the-Valley Tincture, from 0.004 to 0.013 mg/mL in the medicinal product Zelenin Drops, and from 0.005 to 0.007 mg/mL in the medicinal products Carniland® and Valocormid. For the Lily-of-the-Valley Extract Reference Standard, the content of convallatoxin amounted to 0.029 mg/mL.

Development of a liquid chromatography method for the analysis of oil extract of artemisia cina

Introduction. The problem of development and implementation of own drugs in Kazakhstan today is acute and urgent. The solution to this problem is possible through the use of own resources – domestic medicinal plant raw materials. A promising medicinal raw material is Artemisia cina – an endemic medicinal plant of the of the Turkestan region of Kazakhstan.Aim. Designing a liquid chromatography methodology to analyze the oil extract obtained from Artemisia cina.Materials and methods. Standard sample (SS) of santonin, Artemisia cina’s oil extract. The substance was identified and quantitatively determined using an Agilent Technologies 1200 liquid chromatograph (USA) equipped with ChemStation software.Results and discussion. The main active substance of the oil extract was analyzed using high-performance liquid chromatography (HPLC) method. Choosing the separation conditions for the column involves determining the best composition of the mobile phase and the rate of elution. There were used a reversed-phase system with sorbent C18 and a mobile phase consisting of acetonitrile and a phosphate buffer with a pH of 6.8. Chromatographic studies of the substance were carried out in a gradient mode at an analytical wavelength of 237 nm. The retention time of the standard sample (SS) of santonin matched the retention time (tR) of santonin isolated from the oil extract of Artemisia cina and amounted to 14.3 minutes.Conclusion. A liquid chromatography method has been established for the identification and quantitative determination of the oil extract, focusing on the main active substance, santonin.

Low-cost digital colorimetric sensor for rapid on-site determination of ascorbic acid in vegetable- and fruit-based purees and juices

Ascorbic acid is essential for human health due to its potent antioxidant properties; however, excessive intake can lead to adverse effects. This has created a high demand for simple and cost-effective analytical techniques to determine this analyte outside of laboratory settings for food quality control. In this study, a portable colorimetric sensor was developed for the quantitative on-site determination of ascorbic acid. The technique is based on the reduction of phosphorus heteropoly acid by ascorbic acid, resulting in the formation of a blue-colored product. The heteropoly acid was immobilized on a polymer template in the sensor's indicator zone with menthol used as an environmentally friendly extractant to enhance the device’s stability and extend its shelf life. The colorimetric sensor demonstrated reliable detection with a low limit of detection of 5mgkg-1, calculated based on a blank test using 3σ. Under optimized conditions, the linear detection range was 15-150mgkg-1. The disposable sensors were applied to determine ascorbic acid in fruit and vegetable juices and purees for baby food, with recovery rates between 88 and 110%. This easy-to-produce and ready-to-use technique presents significant potential for mass on-site screening of ascorbic acid in food samples.

Application of liquid chromatography-mass spectrometry for the determination of semaglutide in human serum in clinical pharmacokinetic studies

Introduction. Semaglutide preparations are an important therapeutic option for patients suffering from type 2 diabetes mellitus and obesity due to their high efficacy and the expected increase in the prevalence of these diseases. Consequently, there is a growing need for the development of domestic analogs of semaglutide requiring bioequivalence studies. This study proposes the use of high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) as an alternative to the widely used immunoassay for the quantitative determination of semaglutide in human serum.Aim. To develop and validate a method for the quantitative determination of semaglutide in human serum using HPLC-MS/MS.Materials and methods. Serum sample preparation was based on protein precipitation using an acetonitrile-methanol mixture. Liraglutide was selected as the internal standard. The mobile phase consisted of 0.3% formic acid in water and acetonitrile. The stationary phase was represented by a Phenomenex Kinetex C18 chromatographic column 100×3.0 mm, 5 μm, 100 Å. Ionization of semaglutide and liraglutide was performed in positive electrospray mode. Detection was carried out in multiple reaction monitoring mode (MRM).Results. The method demonstrated high accuracy and precision, with relative error and relative standard deviation values of less than 15% across all quality control levels. The confirmed analytical ranges of the method were 0.50–200.00 ng/mL and 1.00–800.00 ng/mL. Over 3.400 volunteer samples were analyzed as part of the studies. Compared to the ELISA method, the proposed method provides higher selectivity and reproducibility of measurements.Conclusions. The method has been developed that provides reproducible quantitative determination of semaglutide in human blood serum. The method was validated in accordance with EAEU requirements and was successfully applied in bioequivalence studies of semaglutide GP40331 (GEROPHARM LLC, Russia). The method is suitable for conducting pharmacokinetic studies of other semaglutide preparations.

A high-performance thin-layer chromatography densitometric method for the separation of isomeric ceftriaxone in powder for injection formulation

The aim of this study was to develop and validate a High-Performance Thin Layer Chromatographic (HPTLC) method for simultaneous determination of ceftriaxone and ceftriaxone e-isomer in powder for injection formulation. Ceftriaxone sodium injection is an antibiotic that used globally. It has Z/E geometrical conformation, in which ceftriaxone sodium and 3 ene-isomer have Z- conformation while (E)-isomer has E- conformation and the potential toxicity of ceftriaxone (E)-isomer has been reported. Thus, to safeguard the public health, a simple and easy to use, rapid and reliable method was developed for qualitative and quantitative determination of ceftriaxone sodium and its (E)–isomer. Samples were applied on HPTLC glass plates precoated with silica gel 60F254 by using Linomat semi-auto sampler. Separation was carried out using acetone, triethyl amine, water, chloroform and ethyl acetate as a mobile phase in different ratios. The Rf values of separated compounds were 0.51 ± 0.01 and 0.62 ± 0.01 for ceftriaxone sodium and ceftriaxone (E)-isomer respectively. The method was validated by studying Specificity, Linearity, Accuracy, Precision, Robustness, Limit of Detection (LOD) and Limit of Quantification (LOQ) and Solution stability. The developed method was successfully, sensitive, simple, precise, accurate, robust and applicable for the simultaneous determination of ceftriaxone sodium and ceftriaxone (E)-isomer in powder for injection formulation.

Benchtop NMR spectroscopy for quantitative determination of milk fat and qualitative determination of lactose: from calibration curve to deep learning

Benchtop NMR spectroscopy for quantitative determination of milk fat and qualitative determination of lactose: from calibration curve to deep learning

Comprehensive characterization of active components in Salvia miltiorrhiza using polarity-partitioned two-dimensional liquid chromatography coupled with mass spectrometry

Salvia miltiorrhiza, a widely used traditional Chinese medicine, contains a complex matrix of hydrophobic diterpenoids and hydrophilic phenolic acids, presenting significant challenges in comprehensive analysis. In this study, an online polarity-partitioned two-dimensional liquid chromatography coupled with mass spectrometry (2D-LC-MS) method was developed for comprehensive analysis of both lipophilic and hydrophilic active components in Salvia miltiorrhiza. The method integrated hydrophilic interaction liquid chromatography (HILIC) and reversed-phase liquid chromatography (RPLC), facilitating the efficient separation of compounds across a wide range of polarities. An online dilution strategy was implemented, minimizing sample loss and enhancing the method's utility for quality control and chemical characterization of complex herbal matrices. Compared with other LC methods, this approach significantly improved analyte coverage, resolution, and analysis efficiency. Under optimal conditions, 150 active components were successfully identified, including 33 compounds newly discovered in Salvia miltiorrhiza. Additionally, the validated online method was applied to the quantitative determination of 16 quality markers of Salvia miltiorrhiza from different sources. The results demonstrated the online method's potential as a superior alternative to existing techniques, offering broader applicability in traditional Chinese medicine research.

High-resolution NMR spectroscopic approaches to quantify PET microplastics pollution in environmental freshwater samples

Reliable identification and precise quantification of microplastics pollution of the environment are essential prerequisites to comprehend the impact of microplastics on Earth’s ecosystems. In this study, we propose a workflow to examine polyethylene terephthalate (PET) contamination of environmental surface waters by applying high-resolution nuclear magnetic resonance (NMR) spectroscopic approaches. The detection of PET by high-resolution NMR spectroscopy enables the unambiguous identification and - at the same time - precise quantification at atomic resolution independent from the size of the particles obtained from surface waters. Monitoring the properties of translational diffusion and relaxation of PET chains present in the samples obtained from Lake Constance water by filtration (‘Manta trawls’), extraction and dissolving, hints towards a rather heterogeneous distribution in length of the PET chains. The workflow developed here achieved a limit of detection of 192.2 ng PET and a recovery rate of 88 ± 25% for PET microplastics that was spiked to the Manta trawls. The NMR driven analysis led to a concentration determination of 335 ± 200 ng PET per cubic meter of Lake Constance water. The workflow developed here offers not only a simple and reliable quantitative determination of the mass of PET in environmental samples independent of particle size but is additionally providing insights into the inherent polymeric features of PET, which are not accessible through other established methods of microplastics detection. Therefore, a broad application of the NMR spectroscopic approach presented here can be assumed.

Solvent-Based and Matrix-Matched Calibration Methods on Analysis of Ceftiofur Residues in Milk and Pharmaceutical Samples Using a Novel HPLC Method.

The matrix effect is accepted as one of the critical factors that affect trueness, and it is especially important in the analysis of critical compounds, such as drugs, toxins and pesticides, in complex matrices. Ceftiofur (CEF) is a leading drug used in dairy industry for pulmonary infections. Because milk has a complex matrix, which is rich in fats, proteins and many other compounds, the determination of CEF in milk products deals with issues of trueness. On the other hand, pharmaceuticals also have a complex composition as they contain not only the active pharmaceutical ingredient but also many excipients, such as preservatives and pH modifiers. Due to its frequent use, its residues can be found in meat products or exist as an excreted compound in urine, milk and so on. The aim of this study was to investigate the effect of different calibration methods on quantitative estimation of CEF in milk and pharmaceutical samples. CEF was analysed using a new HPLC method, in which separation was achieved on a C18 bonded fused-core silica particle column by using isocratic elution; the method was optimized by testing different chromatographic conditions and validated according to the ICH Q2(R1) and United States Pharmacopeia guidelines. Interestingly, it was found that CEF signals in milk samples were higher than the ones at the same level prepared in calibration solutions with a ratio of 11.28:1. This finding reveals the necessity of matrix-matched calibration for accurate quantitative determination of CEF in milk samples. Moreover, the milk in the market and the most used pharmaceutical formulations were analysed using the current method.

Analytical Method Developement and Validation of Beclomethasone, Clotrimazole, Ofloxacin, Lidocaine by RP-HPLC in Combination Dosage Form

A rapid and precise method (in accordance with ICH guidelines) is required for the quantitative simultaneous determination of drugs in a combined pharmaceutical dosage form. The pursuit of desired quality is a continual challenge for pharmaceutical industries, necessitating a meticulous approach known as validation. Sensitive and specific RP-HPLC method involving UV detection was carried for determination and quantification of various drug in combination dosage form. The aim is "Analytical Method developement and Validation of Beclomethasone, Clotrimazole, Ofloxacin, Lidocaine by RP- HPLC In Combination Dosage Form " as per ICH guidelines. The developed method was validated for various parameters as per ICH guidelines like system suitability, specificity, linearity, system precision, method precision, accuracy, ruggedness and robustness. The separation method was carried out by using a mobile phase A consisting of Potassium dihydrogen phosphate buffer (0.05M): Methanol 45:55 v/v) pH 3.5 ± 0.1 and Mobile phase B comprises Acetonitrile in the ratio of 50:50 v/v. The detection was carried out by using UV detector at 300nm. The column was Agilent C 18 (250X4.6mm) 5µ. The flow rate was selected as 1.5 ml/min. The retention time of Ofloxacin, Lidocaine, Beclomethasone, and Clotrimazole, was found to be 5.67, 9.44, 18.29, and 21.85 respectively.

ВИТАМИН D3: ПОДРОБНАЯ ХАРАКТЕРИСТИКА СУБСТАНЦИИ И АНАЛИЗ

The article examines in detail the issues of standardization of the obtained vitamin D substance using its own original technological scheme, and the possibility of further use of the substance to create a standard sample (SS). The work traces the current problem associated with the lack of production of domestic vitamin D substance. The object of study is the vitamin D substance isolated from natural raw materials. To assess the quality of the obtained substance, quantitative and qualitative determination methods, high-performance liquid chromatography (HPLC) at a wavelength of 265 nm, IR spectroscopy in the emission range of the spectrum from 4000 cm-1 to 400 cm-1, organoleptic method, polarimetry, refractometry and other methods of analysis were used. The obtained vitamin D substance, according to its quality characteristics, can be confidently used not only as a material for the manufacture of SS, but also as a starting substance in the pharmaceutical, food and agricultural sectors of the national economy.

Highly Sensitive Determination of Copper Ions as MnO2 Etching Inhibitor in Single-Particle Nanoplasmonic Imaging.

Dark-field microscopy (DFM) imaging based on plasmonic metal nanoparticles has garnered significant attention. Here, we exploit the susceptibility of MnO2 to reduction to modulate the local dielectric environment of an Au nanoparticle core through the etching/antietching effects of specific targets on the encapsulated MnO2 shell. The presence of d-penicillamine promotes MnO2 etching, while the chelation of d-penicillamine with Cu2+ effectively inhibits this etching. By recording the Cu2+-induced color shift of scattered light from orange to bright green at the single-particle level and performing the statistical analysis of the green-to-red (G/R) values in DFM images, we achieved quantitative determination of Cu2+ with a wide linear range (0.1-10 μM) and a low limit of detection (4.55 nM). With the facile and reliable Cu2+ assay in real-world samples exemplifying the practicality of the single-particle nanoplasmonic imaging method, this work may inspire future DFM-based investigations of nanoshell etching inhibition processes.

USING RETROSPECTIVE DATA TO ASSESS THE UNCERTAINTY OF INDICATORS OF BIOLOGICAL SAFETY OF FOOD AND FEED RAW MATERIALS

The results of the analysis of the advantages and disadvantages of the use of retrospective data for the implementation of the evaluation of uncertainty in the measurement of indicators of biological safety of food and feed raw materials are given. The model measurement procedure used quantitative determination of genetically modified organisms by means of polymerase chain reaction in real time 250 measurement results of certified reference material with a content of 0.1% genetically modified soybean line obtained under conditions of intra-laboratory reproducibility and 10 results of relevant inter-laboratory comparisons with the participation accredited provider. The suitability of retrospective data was assessed by the Shapiro-Wilk criterion and statistical controllability analysis using standardized score charts and modified Shewhart charts, uncertainty by 4 methods described in general and branch international guidelines and regulations. The results of using a combination of modified Shewhart maps demonstrate the acceptability of this approach for establishing the suitability of retrospective measurement results as input data for uncertainty assessment. By integrating additional "fitness limits" to a set of standardized control limits, this analysis acquires the ability to simultaneously establish not only stability, through the interpretation of geometric patterns, but also compliance with specific criteria. Using this approach, objective evidence of the suitability of retrospective data for estimating measurement uncertainty was obtained. The distribution of retrospective data obtained under conditions of intralaboratory reproducibility is assumed to be normal. As a result of the assessment of statistical controllability and compliance with the established criteria, objective evidence of the suitability of the data for uncertainty assessment was obtained. Analysis of uncertainty intervals of subgroups with the volume of 25 measurements, using 4 assessment methods, demonstrated significant variability in the results of measuring biological safety indicators. The uncertainty interval could narrow or widen by almost 100% of the value within fifty measurements. Median values obtained using different uncertainty estimation methods were 2.69%, 22.69%, 39.23, and 43.08%. This variability is due to the limited coverage of sources of uncertainty, which is inherent in each of the analyzed methods. The most optimal method is the evaluation based on the routine measurement of the certified reference material. Retrospective results of routine measurement of certified reference material and interlaboratory comparisons are an effective source of input data for assessing the uncertainty of the results of measuring biological safety indicators of agricultural raw materials. There is a need for further research to establish an assessment model that will provide an opportunity to take into account the optimal number of influential sources of uncertainty that are inherent in biological systems and cannot be simultaneously taken into account using existing approaches offered by standard assessment methods.