Chemical Analysis Methods Research Articles

Effect of Microplastics and Phenanthrene on Soil Chemical Properties, Enzymatic Activities, and Microbial Communities

Microplastic and polycyclic aromatic hydrocarbon (PAHs) pollution have received increasing attention due to their ubiquitous distribution and potential risks in soils. However, the effects of microplastics-PAHs combined pollution on soil ecosystems remain unclear. Polyethylene (PE)/polypropylene (PP) and phenanthrene (PHE) were selected as the representatives of microplastics and PAHs, respectively. A 300-day soil microcosm experiment was conducted to study the single and combined effects of PE/PP and PHE on soil chemical properties, enzymatic activities, and bacterial communities (i.e., quantity, composition, and function), using the soil agricultural chemical analysis method and 16S amplicon sequencing technology. The interactions of soil properties, enzyme activities, and flora in the presence of PE/PP and PHE were analyzed. The results showed that the addition of PE/PP and PHE slightly changed the pH, available phosphorus (AP), and microbial quantity (i.e., bacteria, actinomycetes, and mold) but considerably increased the fluorescein diacetate hydrolase (FDAse) activity. There was a significant enhancement of soil organic matter (SOM) and urease activity in PE, PP, PHE-PE, and PHE-PP amended systems. PHE, PHE-PE, and PHE-PP obviously increased the dehydrogenase/neutral phosphatase activities and available nitrogen (AN) content. PHE had little effect on the microbial community. The PE, PP, PHE-PE, and PHE-PP addition influenced the microbial community to some extent. PE/PP and PHE showed positive effects on the energy production, growth, and reproduction of soil microorganisms and then accelerated the metabolism/degradation of pollutants and membrane transport. The changes in AN and SOM induced by PE/PP and PHE were the key factors affecting soil enzyme activities. Alterations in AN, AP, and pH were mainly responsible for the increase in microbial population. The changes in the microbial community were related to soil chemical properties and enzyme activities, and SOM had a significant effect on the microbial community. The presence of different carbon sources (PE/PP and PHE) in the soil and the microbial interaction also affected the microbiota. In conclusion, the addition of single or combined pollutants of PE/PP and PHE influenced the soil chemical properties, enzymatic activities, bacterial communities, and their interaction processes, thus facilitating the adaptation of the microbial community to pollutant stress.

A pH-enhanced resolution in benchtop NMR spectroscopy.

NMR spectroscopy is one of the most potent methods in analytical chemistry. NMR titration experiments are particularly useful since they measure molecular binding affinities and other concentration-dependent effects. These experiments, however, require a long series of measurements. An alternative to these serial measurements has recently been presented, exploiting a pH (or generally - a concentration) gradient along the NMR tube. The proposed experiment, although efficient, was based on the sensitivity- and hardware-demanding chemical shift imaging (CSI) method. Thus, it is practically limited to high-resolution NMR spectrometers. This paper proposes modifying and adapting the approach to the popular and cost-efficient benchtop NMR machines. Instead of CSI, we use a device that shifts the NMR tube vertically to measure the spectra of different sample volumes, which have different pH values due to the established gradient along the tube. We demonstrate the potential of the method on the test samples of L-tyrosine and 2,6-lutidine, and two real samples from the food industry - an infant formula and an energy drink. The proposed method boosts spectral resolution and allows for the sampling of a broader range of pH values when compared to the original approach.

Perfil físico-químico e proteico do soro de leite de cabra

ABSTRACT: The cheese after processing, generates whey, which is a residue that has potential benefit to human health. However, there are still few studies that seek to evaluate the composition and potential benefits of goat milk whey, even though it is a promising dairy source. Despite this, the large-scale generation of this waste can favor the environmental impact when improperly disposed of. Given this, the use of all content of dairy production can reverse this impact and increase the income of the dairy industry. Thus, this research prepared a powdered product based on goat’s milk whey from the spray drying technique and evaluate its physicochemical composition by chemical analytical methods and protein profile through polyacrylamide gel electrophoresis. The elaborated product had a higher carbohydrate content than protein, and the identification of protein fractions showed that the most expressive bands represented beta-lactoglobulin and alpha-lactoalbumin. Therefore, the elaborated product has the potential to generate novel products for human consumption and with potential health benefits.

Resonant Raman scattering on graphene: SERS and gap-mode TERS.

Nanoscale deformations and corrugations occur in graphene-like two-dimensional materials during their incorporation into hybrid structures and real devices, such as sensors based on surface-enhanced Raman scattering (SERS-based sensors). The structural features mentioned above are known to affect the electronic properties of graphene, thus highly sensitive and high-resolution techniques are required to reveal and characterize arising local defects, mechanical deformations, and phase transformations. In this study, we demonstrate that gap-mode tip-enhanced Raman Scattering (gm-TERS), which offers the benefits of structural and chemical analytical methods, allows variations in the structure and mechanical state of a two-dimensional material to be probed with nanoscale spatial resolution. In this work, we demonstrate locally enhanced gm-TERS on a monolayer graphene film placed on a plasmonic substrate with specific diameter gold nanodisks. SERS measurements are employed to determine the optimal disk diameter and excitation wavelength for further realization of gm-TERS. A significant local plasmonic enhancement of the main vibrational modes in graphene by a factor of 100 and a high spatial resolution of 10 nm are achieved in the gm-TERS experiment, making gm-TERS chemical mapping possible. By analyzing the gm-TERS spectra of the graphene film in the local area of a nanodisk, the local tensile mechanical strain in graphene was detected, resulting in a split of the G mode into two components, G+ and G-. Using the frequency split in the positions of G+ and G- modes in the TERS spectra, the stress was estimated to be up to 1.5%. The results demonstrate that gap-mode TERS mapping allows rapid and precise characterization of local structural defects in two-dimensional materials on the nanoscale.

Advancements in the preparation technology of small molecule artificial antigens and their specific antibodies: a comprehensive review.

Small molecules find extensive application in medicine, food safety, and environmental studies, particularly in biomedicine. Immunoassay technology, leveraging the specific recognition between antigens and antibodies, offers a superior alternative to traditional physical and chemical analysis methods. This approach allows for the rapid and accurate detection of small molecular compounds, owing to its high sensitivity, specificity, and swift analytical capabilities. However, small molecular compounds often struggle to effectively stimulate an immune response due to their low molecular weight, weak antigenicity, and limited antigenic epitopes. To overcome this, coupling small molecule compounds with macromolecular carriers to form complete antigens is typically required to induce specific antibodies in animals. Consequently, the preparation of small-molecule artificial antigens and the production of efficient specific antibodies are crucial for achieving precise immunoassays. This paper reviews recent advancements in small molecule antibody preparation technology, emphasizing the design and synthesis of haptens, the coupling of haptens with carriers, the purification and identification of artificial antigens, and the preparation of specific antibodies. Additionally, it evaluates the current technological shortcomings and limitations while projecting future trends in artificial antigen synthesis and antibody preparation technology.

ӨНЕРКӘСІПТІҢ ТЕХНОГЕНДІК ҚАЛДЫҚТАРЫ ҚҰРЫЛЫС МАТЕРИАЛДАРЫН ӨНДІРУГЕ БАҒАЛЫ ШИКІЗАТ

The growth of industrial production leads to an increase in the volume of waste generated and the costs of their storage, concentration, burial, disposal, capture or neutralization, especially in the non-fer-rous metallurgy of Kazakhstan. The metallurgical production system is based on technological processes that actively interact with the environment. The bulk of existing technological processes are built on the principle of open systems, on the one hand consuming raw materials and energy, and on the other – producing finished products and waste. Taking into account the current level of production, a significant period of time is still required to significantly reduce production waste associated with the improvement of technological processes. During these periods, waste accumulating in industrial and other territories continues to intensively pollute the soil, air and water sources.The purpose of the work: Utilization of man-made industrial waste and development of technologi-cal bases for the production of composite cements based on them. The use of waste “carbonate-barium tailings”, phosphoric and blast furnace slags in the production of composite cements, on the one hand, improves the ecological situation of the region, and on the other hand, allows us to save reserves of natural resources for future generations, especially non-renewable ones, and prevent the destruction of natural landscapes with natural self-development. In the course of the work, standard and generally ac-cepted research methods were carried out: chemical and mineralogical methods of analysis, scanning electron microscopy, physical and mechanical tests.

ФОРМУВАННЯ КОМПОЗИТУ ПРИ ВАРІЮВАННІ ДИСПЕРСНОСТІ НАПОВНЮВАЧА ТА ВИДУ ЗВ’ЯЗУЮЧОГО

The aim of this study was to investigate polymer composites based on andesite of different dispersion as a filler with different types of polymer matrix for further development of production technology. Varying the types and concentration of mineralfillers of different genesis, including volcanic rocks, is one of the ways to modify polymer composite materials. The choice of filler type is an important factor influencing the structure formation and properties of the resulting composite. At the same time, varying the particle size distribution of the filler and its quantitative ratio with the matrix makes it possible to adjust the performance properties of the resulting composite materials within a wide range. In addition, the surface properties of thefiller particles and the chemical nature of the polymer matrix are of great importance. The possibility of expanding the range and increasing the operational reliability of composite materials when using new types of natural raw materials determine therelevance of this research. To achieve this goal, a set of modern methods of physical and chemical analysis and standardised testing of materials was used in the study. The object of the study was composite materials using andesite screenings as a fractionated filler and copolymers as a matrix. Changes in the physical and mechanical properties of the composites were determined by varying the content (55-85 wt.%) and granulometry of the filler and the type of polymeric binder. According to the test results, it is possible to adjust the parameters of the properties of polymer composites, while the range of their changes is as follows: water absorption 2.2-14.9 %, density 1.24-1.96 g/cm3, abrasion 0.005-0.1 g/cm2, elastic modulus 41-83 Pa/mm2, which indicates the prospects of manufacturing and practical use of the obtained wear-resistant composites in construction

Nova HPLC metoda za istovremeno određivanje empagliflozina i dapagliflozina - razvoj, validacija, testiranje robusnosti i procena ekološke prihvatljivosti

Empagliflozin (EMPA) and Dapagliflozin (DAPA) are mainly recommended for the treatment of type 2 diabetes mellitus and heart failure. Based on the principles of green analytical chemistry, a simple, rapid and robust HPLC method was developed for the determination of both analytes in bulk. An isocratic protocol was developed using a C18 column, with a mobile phase consisting of just 30% organic modifier (ACN), while the remaining 70% was HPLC water. The run was completed within 4 min, with a flow rate of 1.20 mL/min, while UV detection took place at 230 nm. The method was then validated according to the ICH Q2 (R1) guidelines, and all the parameters examined were within the specified limits. Furthermore, the robustness of the method was evaluated by employing a factorial experimental design. Finally, the environmental friendliness of the proposed method was assessed by using the Analytical GREEness (AGREE) metric tool. The proposed method can be used for analysis of EMPA and DAPA in bulk, with potential application to the relevant pharmaceuticals.

Exploring the mechanism of Si-Ni-San against depression by UPLC-Q-TOF-MS/MS integrated with network pharmacology: experimental research.

Depression is becoming an urgent mental health problem. Si-Ni-San has been widely used to treat depression, yet its underlying pharmacological mechanism is poorly understood. Thus, we aim to explore the antidepressant mechanism of Si-Ni-San by chemical analysis and in-silico methods. Compounds in Si-Ni-San were determined by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). Then, bioactive compounds were obtained from Traditional Chinese Medicines for Systems Pharmacology Database and Analysis Platform and SwissADME, and the potential targets of which were acquired from SwissTargetPrediction. Depression-related targets were collected from GeneCards. The intersection between compound-related targets and depression-related targets were screened out, and the overlapped targets were further performed protein-protein interaction, biological functional and pathway enrichment analysis. Finally, networks of Si-Ni-San against depression were constructed and visualized by Cytoscape. One hundred nineteen compounds in Si-Ni-San were determined, of which 24 bioactive compounds were obtained. Then, 137 overlapped targets of Si-Ni-San against depression were collected. AKT1, PIK3R1, PIK3CA, mTOR, MAPK1 and MAPK8 were the key targets. Furthermore, PI3K-Akt signalling pathway, serotonergic synapse, MAPK signalling pathway and neurotrophin signalling pathway were involved in the antidepressant mechanism of Si-Ni-San. It showed that components like sinensetin, hesperetin, liquiritigenin, naringenin, quercetin, albiflorin and paeoniflorin were the mainly key active compounds for the antidepressant effect of Si-Ni-San. This study demonstrated the key components, key targets and potential pharmacological mechanisms of Si-Ni-San against depression. These results indicate that Si-Ni-San is a promising therapeutic approach for treatment of depression, and may provide evidence for the research and development of drugs for treating depression.

INCREASING THE EFFICIENCY OF LASER MEDICAL DEVICES WITH FIBER-OPTIC LIGHT GUIDES UNDER THE CONDITIONS OF EXTERNAL THERMAL EFFECTS

Study of the influence of the controlled parameters of the electron beam (the density of the thermal effect Fn and the speed of movement (scanning) along the treated surface V) on such important parameters of the quality of the end surfaces of the light guides as their cleanliness and micro-roughness, which have a significant impact on the transmission coefficient of IR radiation kl, are now limited. Therefore, the purpose of this work is to establish the regularities of the influence of the controlled parameters of the electron beam, to determine the optimal ranges of their application, which do not lead to the destruction of the treated end surfaces of light guides made of optical glass and maximize the IR transmission coefficient by increasing their purity and reducing micro-roughness, which makes it possible to increase the efficiency of devices in conditions of external thermal effects.The study of the thermal effect of an electron beam on optical glass elements was carried out on specialized electron beam equipment protected by Ukrainian patents. Modern methods of physical and chemical analysis were used to conduct experimental research. The obtained experimental data were processed in dialogue mode and in real time on a PC using modern methods of mathematical statistics and standard application programs. At the same time, the relative measurement error of the considered parameters does not exceed 5...7 %.Experimental studies were carried out and optimal ranges of electron beam parameter changes were established (thermal action density Fn = 3∙106...7∙108 W/m2; scanning speed V = 6∙10-3...4∙10-2 m/s), within in which the most significant improvement in the quality parameters of the processed end surfaces of light guides is observed (increasing the cleanliness of the surfaces and reducing their micro-roughness), which leads to an increase in the spectraltransmittance of IR radiation. As a result, the maximum allowable range of propagation of laser radiation in light guides increases and provides better diagnostics, therapeutic and surgical treatment, which contributes to increasing the efficiency of laser medical devices, especially when they are operated taking into account external thermal effects.

Stability of Alizarin for Aqueous Organic Redox Flow Batteries

The intermittent nature of renewable energy sources like solar and wind requires suitable large-scale energy storage technologies to properly respond supply and demand of energy. Aqueous organic redox flow batteries (AORFBs) have demonstrated great potential to revolutionize grid-scale energy storage as a result of their low-cost, safety and ability to separate energy and power1. However, most of the organic compounds suffer from lack of sufficient long-term stability.Alizarin (1,2-dihydroxyanthraquinone) is a low-cost, nontoxic, and industrially accessible dye which could potentially be used as an affordable redox-active negative electrolye (negolyte)2. Here, we present an in-depth investigation on the long-term cycling stability of Alizarin. Furthermore, we implement an aggressive cycling conditions to investigate the degradation of the cycled negolyte within just a single day, achieving an equivalent capacity fade percentage as electrolyte cycled for over two weeks3. The capacity fade of alizarin was partially mitigated by the employment of a SOC restriction strategy which was able to decrease the capacity fade rate by more than 60 %.4 Capacity fade measured via cycling is corroborated by ex situ chemical analysis methods.

Polychlorinated dibenzo-p-dioxins and furans: methods of analysis, distribution in the Moscow region and application of biotesting methods to them

The review presents data on chemical-analytical methods of PCDD, PCDF determination and biotesting methods used for toxicological assessment of pollutants. Distribution of PCDDs, PCDFs on the territory of Moscow is analyzed. Analysis of publications of Russian and foreign authors showed that the currently existing methods of biotesting are in fact untested for dioxins. In order to quickly establish the toxicological effect of persistent organic pollutants in soil, it is suggested to use biotesting methods, with inclusion of test organisms representing the main trophic levels of ecosystems: producers, consumers, and decomposers.

Detection of adulteration of Alpaca (Vicugna pacos) meat using a portable NIR spectrometer and NIR-hyperspectral imaging

Alpaca meat has high protein content; good tenderness and low intramuscular fat content, being more expensive than meat from other animals (e.g., beef). Hence, alpaca meat may face adulteration, which demands chemical analytical methods to be identified. In this study, chemical-free methods, e.g., portable NIR spectrometer and NIR-HSI were employed to detect adulteration of alpaca meat with pork, chicken, and beef (0 – 50% w/w). Spectral analysis revealed significant differences in the spectra of pure alpaca meat samples using NIR-HSI. Principal Component Analysis (PCA) grouped samples into pure and non-pure alpaca meat using both devices as sources of spectra. Next, we developed and validated one-class Data Driven Soft Independent Class Analogy (DD-SIMCA) models to authenticate pure alpaca meat. DD-SIMCA models using spectra acquired by both devices achieved 100% sensitivity and 100% specificity for external set of samples. Besides, Partial Least Squares Regression (PLSR) based on NIR-HSI outperformed the portable NIR spectrometer to predict the concentration of adulterant in alpaca meat. In conclusion, both devices supported by chemometric approaches can be implemented as screening methods to detect adulteration in alpaca meat.

METHODOLOGY OF SPECIFIC ENZYME BIOTEST-SYSTEMS IN VITRO APPLICATION IN HERBAL MEDICINES COMPLEX LABORATORY QUALITY CONTROL SYSTEM

Relevance. Improving methods for quality control of medicines, including those of plant origin, is one of the urgent tasks of modern pharmaceutical science and practice. The growing interest in herbal medicine stimulates not only the expansion of the diversity of raw materials and the development of new drugs, but also the constant improvement of approaches and methods for controlling their quality. The purpose of the study is to develop a methodology for the use of specific in vitro enzyme biotest systems (IBTS) in complex laboratory quality control of herbal medicines for additional assessment of their biological activity, which determines therapeutic effectiveness, in addition to physical, physicochemical, and chemical indicators. Material and methods. We used in silico (PASS), in vitro (specific enzyme biotest systems) and in vivo (experimental models) methods. Results. A method has been developed for the use of specific in vitro enzyme biotest systems (IBTS) in complex laboratory quality control of medi-cines, as well as methods of physical, physico-chemical, and chemical analysis to assess their biological properties, which determine the therapeutic effectiveness of medicines. Conclusions. Specific enzyme biotest systems make it possible to identify the specific biological activity of research objects and confirm the feasibil-ity of their use in an in vitro quality control system for herbal medicines at different stages of their life cycle, as demonstrated by the example of ex-tracts from native and biotechnological raw materials, as well as experimental dosage forms, developed at FGBNU VILAR, and comparison drugs.

Optimization of post-annealing temperature for high-performance synaptic transistors based on In–Ga–Zn–O channel and trap layers

Synaptic transistors using an indium–gallium–zinc oxide (IGZO) charge trap layer (CTL) have great potential for high-performance neuromorphic applications due to their excellent stability and high linearity in conductance modulation. Since the high conductivity of the IGZO CTL enhances charge de-trapping performance, the post-annealing process, which directly affects the conductivity of the film, should be carefully conducted. In this study, we investigated the effect of post-annealing temperature (TPA) on the charge de-trapping performance of synaptic transistors. The synaptic transistor showed superior charge de-trapping performance at a TPA of 250 °C, resulting from the increased conductivity of the CTL. Through various electrical and chemical analysis methods, it was revealed that the hydrogen decrease within the CTL and the oxidation–reduction reaction at the interface between the tunneling layer and the CTL contributed to the significant increase in the conductivity of the CTL. The synaptic transistor with the optimal TPA exhibited high linearity of potentiation (αp: 0.56) and depression (αd: −0.65) with 64 conductance levels, enabling the spiking neural network simulation to achieve a high accuracy of 88.75% using a Fashion-MNIST dataset. This work shows that TPA is one of the critical process strategies for the high charge de-trapping performance of the synaptic transistor by inducing the chemical reaction at the CTL interface and hydrogen content change within the CTL.

Application of snail shells as a heterogeneous catalyst for rapeseed oil butyl esters production

ABSTRACT Synthesis of fatty acid butyl esters using snail shells is attractive and increases the share of renewable resources because the snail shells are a waste of the food industry and 1-butanol can be obtained from renewable resources. Chemical and instrumental analysis methods (XRDA, FT-IR, EDS) were used for the evaluation of the chemical composition of snail shells. It was found that composition slightly depends on the kind and growing conditions, but in all the cases the main component in raw shells is CaCO3. After calcination for 5 h at a temperature of 850 °C, almost pure CaO (93.69 ± 0.43% %) is formed, which is used as a catalyst in the triglyceride transesterification process. SEM studies showed that the structure of the shells becomes porous after calcination, which increases the efficiency of the process. The Response surface methodology was used for the optimization of rapeseed oil transesterification with 1-butanol. It was found that the optimum transesterification conditions when the reaction temperature is 110°C are the following: 1-butanol-to-oil molar ratio of 10.6:1, a snail shell content of 7.53 wt%, and a reaction time of 10.77 h. Under these conditions, the 99.25 wt% yield of rapeseed butyl esters was obtained.

Advancing forensic research: An examination of compositional data analysis with an application on petrol fraud detection

In recent years, numerous studies have examined the chemical compounds of petrol and petrol data for forensic research. Standard quantitative methods often assume that the variables or compounds do not have compositional constraints or are not part of a constrained whole, operating within an Euclidean vector space. However, chemical compounds are typically part of a whole, and the appropriate vector space for their analysis is the simplex. Biased and arbitrary results result when statistical analysis are applied on such data without proper pre-processing of such data. Compositional analysis of data has not yet been considered in forensic science. Therefore, we compare classical statistical analysis as applied in forensic research and the new proposed paradigm of compositional data analysis (CoDa). It is demonstrated how such analysis improves the analysis in petrol and forensic science. Our study shows how principal component analysis (PCA) and classification results are affected by the preprocessing steps performed on the raw data.Our results indicate that results from a log ratio analysis provides a better separation between subgroups of the data and leads to an easier interpretation of the results. In addition, with a compositional analysis a higher classification accuracy is obtained. Even a non-linear classification method - in our case a random forest - was shown to perform poorly when applied without using compositional methods. Moreover, normalization of samples due to laboratory/unit-of-measurement effects is no longer necessary, since the composition of an observation is in compositional thinking equivalent to a multiple of it, because the used (log) ratios on raw and log ratio transformed data are equal.Petrol data from different petrol stations in Brazil are used for the demonstration. This data is highly susceptible to counterfeit petrol. Forensic analysis of its chemical elements requires non-biased statistical analysis designed for compositional data to detect fraud.Based on these results, we recommend the use of compositional data methods for gasoline and petrol chemical element analysis and gasoline product characterization, authentication and fraud detection in forensic sciences.

Abraham solvation parameter model: determination of experiment-based solute descriptor values for 3,5-dimethoxybenzoic acid based on measured solubility data

ABSTRACT A spectroscopic method of chemical analysis is used to determine the mole fraction solubilities of 3,5-dimethoxybenzoic acid dissolved in propanenitrile, in eleven additional alkanol solvents (1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-methyl-1-propanol, 2-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 4-methyl-2-pentanol, 2-ethyl-1-hexanol, cyclopentanol) and in three additional alkyl alkanoate solvents (isopropyl acetate, tert-butyl acetate, methyl butyrate) at 298.15 K. Results from our experimental measurements, combined with published partition coefficient and solubility data, are used to calculate the Abraham model solute descriptors of the monomeric form of 3,5-dimethoxybenzoic acid. In total 62 experimental data points were used in the computation. The calculated solute descriptors describe the experimental solubility and partition coefficient data to within an overall standard deviation of 0.064 log units.

Inversion analysis of soil nitrogen content using hyperspectral images with different preprocessing methods

Unmanned aerial vehicle (UAV) hyperspectral data can provide accurate and detailed spectral information on the surface of features, leading to a better understanding of the physiological characteristics and optical properties of objects. Compared to satellite hyperspectral, UAV hyperspectral has a greater image spatial resolution, but it also collects more impurity information along with more image detail information. The nitrogen (N) content in shallow soils is of great significance for crop growth, and most of its remote sensing inversions are currently based on satellite images, whereas relatively few studies have used hyperspectral UAV images in the near-infrared band for inversions. Based on this, we propose a high-accuracy inversion model based on UAV hyperspectral imagery using an elastic net (EN) dimensionality reduction algorithm combined with a decision tree (DT) model. In this study, a hyperspectral imager carried by a drone was used to acquire the surface soil spectral data of winter wheat in the study area after sowing and fertilizing, and the measured N content of the sampled soil was determined by chemical analysis methods. We used various pre-processing methods to denoise and reduce the dimensionality of the original hyperspectral images and utilized a DT regression model to construct an inversion model of N content with different preprocessing results. Then we compared the accuracy of the models and used the optimal model to obtain the spatial distribution map of soil N content in the study area. The results show that (1) the dimensionality reduction of hyperspectral data can effectively remove redundant information and prevent data overfitting. Among them, the successive projections algorithm and correlation analysis method are more suitable for analyzing pre-processed spectral data, whereas the Lasso and EN algorithms are more suitable for processing original spectral data. (2) For the original spectral images, the EN dimensionality reduction algorithm (R2 of the EN-Unt-DT inversion model is 0.930, RMSE is 0.045) performed better than the other three algorithms. For the pre-processed spectral images, the successive projections algorithm (R2 of the SPA-Pre-DT inversion model is 0.906, RMSE is 0.055) performed better than the other three algorithms. The constructed EN-Unt-DT inversion model had the highest fitting accuracy. The research results provide a corresponding technical reference for the inversion of soil N content using UAV NIR hyperspectral data.

Chemical Composition Analysis and Multi-index Component Content Determination of Compounds in Goupi Plaster Based on UPLC–Q-Exactive-MS and UPLC–MS/MS

ObjectiveThis study sought to evaluate and validate a method for chemical composition analysis and content determination of Goupi plaster components, a conventional prescription preparation of traditional Chinese medicine. This is geared toward providing a basis for quality control research and future development of Goupi plaster.MethodsUPLC–Q-Exactive-MS was used to qualitatively analyze the chemical components of Goupi plaster from different manufacturers in positive and negative ion modes. UPLC–MS/MS method was used to establish the determination methods for the detection of sinomenine, osthole, and cinnamaldehyde in Goupi plaster from different manufacturers.ResultsA total of 291 chemical components were identified in Goupi plaster from four manufacturers, including 97 chemical components with known source and pharmacological activity. Further, we determined the contents of sinomenine, osthole, and cinnamaldehyde.ConclusionIn summary, the UPLC–Q-Exactive-MS method was used to analyze the chemical components of Goupi plaster from different manufacturers. We established the UPLC–MS/MS method to determine the contents of sinomenine, osthole, and cinnamaldehyde in Goupi plaster from different manufacturers. The findings indicated that the method was comprehensive, rapid, and accurate, preliminarily revealing the material basis of Goupi plaster and providing a reference for follow-up development of Goupi plaster.