Purification Method Research Articles

Accurate determination of three new antihypertensive drugs illegally added to food using ultra-high performance liquid chromatography-tandem mass spectrometry

Effective strategies are required to address food safety issues related to the illegal addition of antihypertensive drugs to food and claims of antihypertensive function. In this study, a novel ultra-high performance liquid chromatography-triple-quadrupole mass spectrometry (UHPLC-MS/MS) method was developed for the simultaneous determination of three antihypertensive drugs (azilsartan, candesartan cilexetil, and lacidipine) in 12 food matrices (pressed candies, solid beverages, alternative teas, tea drinks, biscuits, jellies, mixed liquors, oral liquids, medicinal teas, tablets, hard capsules, and soft capsules). Initially, mass spectrometry parameters, such as the collision energies of the three antihypertensive drugs, were optimized. Subsequently, the response intensities and chromatographic separation conditions of the three drugs in different mobile phases were compared. In addition, to enhance the recoveries, various extraction solvents and purification methods, including solid-phase extraction (SPE) columns and the QuEChERS technique, were investigated. In the developed method, sample determination involved three steps. First, the sample was extracted using 0.2% (v/v) formic acid in acetonitrile and then filtered using high-speed centrifugation, in addition, the extracted solution of alternative tea and medicinal tea was purified using the QuEChERS technique. Second, the supernatant was diluted with water, and filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane. Finally, the analytes were separated on an Agilent Eclipse Plus RRHD C18 column (50 mm×2.1 mm, 1.8 μm) using a 5 mmol/L ammonium formate aqueous solution and acetonitrile as the mobile phases under gradient elution conditions and then detected using UHPLC-MS/MS with positive electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. Quantitative analysis was performed using a matrix-matched external standard method. Methodological validation showed good linear relationships for all three antihypertensive drugs in the investigated concentration ranges, with correlation coefficients (r2) greater than 0.996. The limit of detection (LOD) and limit of quantification (LOQ) of lacidipine were 0.02 mg/kg and 0.04 mg/kg, respectively, whereas those of the other two drugs were 0.01 mg/kg and 0.02 mg/kg, respectively. In the 12 food matrices, the average recoveries of the drugs ranged from 86.6% to 107.5% with relative standard deviations (RSDs) of 1.1%-10.9% (n=6) at low, medium, and high spiked levels. Furthermore, this method was successfully applied to the analysis of real food samples. Overall, the newly developed method is simple, rapid, sensitive, accurate, and suitable for the qualitative and quantitative determination of antihypertensive drugs in different food matrices. This work could provide technical support for food safety agencies in implementing measures against the illegal addition of antihypertensive drugs to food.

A novel carbon quantum dot (CQD) synthesis method with cost-effective reactants and a definitive indication: Hot bubble synthesis (HBBBS)

Carbon quantum dots (CQDs) are carbon-based biocompatible quantum dots that have low toxicity, are more soluble in water, have broad application areas, and the surface modification of these can be performed easily. In this study, we present a new CQD synthesis method with cost-effective reactants that can be easily found in laboratories are used. Besides, there is a definitive indication (bubble) for CQD production, unlike the other methods in the literature. The purification method of the CQDs was also optimized in this study. In the beginning of the synthesis, 3 times centrifugation (x3 CF) of the mixture was performed and the optimization of the purification method indicated that x3 CF before 3 days of dialysis membrane tubing (x3 CF & 3 DM) resulted in the formation of the purest CQDs. The characterization of the CQDs was done utilizing UV–VIS spectrophotometer, Fourier Transfer Infrared Spectroscopy (FT-IR), Zetasizer, fluorescence microscopy, Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). It was concluded that the CQD formation depends on the mixing of sulphuric acid:acetone (2:1) ratio in a hot (140-165 °C) and an inert environment, and bubble coverage of the mixture surface(30-60 s). The bubble formation due to the reaction between sulphuric acid and pure acetone at high temperatures gives the developed method’s name of “Hot Bubble Synthesis” (HBBBS).

For catching-by-polymerization oligo purification: scalable synthesis of the precursors to the polymerizable tagging phosphoramidites

The catching-by-polymerization (CBP) oligodeoxynucleotide (oligo or ODN) purification method has been demonstrated suitable for large-scale, parallel, and long oligo purification. The authenticity of the oligos has been verified via DNA sequencing, and gene construction and expression. A remaining obstacle to the practical utility of the CBP method is affordable polymerizable tagging phosphoramidites (PTPs) that are needed for the method. In this article, we report scalable synthesis of the four nucleoside (dA, dC, dG and T) precursors to the PTPs using a route having five steps from inexpensive starting materials. The overall yields ranged from 21% to 35%. The scales of the synthesis presented here are up to 2.1 grams of the precursors. Because the syntheses are chromatography-free, further scaling up the syntheses of the precursors have become more feasible. With the precursors, the PTPs can be synthesized in one step using standard methods involving a chromatography purification.

Enhanced Hg(II) reduction activity over two-dimensional n-n heterojunction MoS2/Bi2WO6 nanocomposites under visible light illumination

The engineering of band structure acts as an effective avenue to promote photocatalytic redox reactions, which can be achieved by fabricating heterojunction photocatalysts. Herein, MoS2 NPs were anchored on the surface of the mesoporous Bi2WO6 network through a facile sol-gel process to form heterostructure MoS2/Bi2WO6 nanocomposites. HR-TEM and XRD results of the obtained MoS2/Bi2WO6 nanocomposite verified the formation of the hexagonal phase of MoS2 and the Bi2WO6 in the orthorhombic phase. The MoS2/Bi2WO6 nanocomposites displayed enhancement harvest in the visible light domain and photocatalytic ability in comparison with the pristine Bi2WO6. The photocatalytic ability of MoS2/Bi2WO6 nanocomposites was assessed by the Hg(II) reduction upon visible light irradiation. The optimal 12% MoS2/Bi2WO6 photocatalyst displayed the superior reduction of Hg(II) about 99% after 50 min, and the rate constant reached 0.1220 min-1 according to pseudo-first-order kinetic, where it was larger three folds than pristine Bi2WO6 (0.0418 min-1). The outstanding photocatalytic ability of n-n heterojunction MoS2/Bi2WO6 photocatalyst was accredited to the huge surface area, wide photoabsorption, and high separation efficiency of photocarriers. The reduction ability of MoS2/Bi2WO6 photocatalyst remained at 94% in the recycle five times, indicating its good reusability and high stability. The obtained heterojunction with the S-scheme mechanism could inhibit the recombination of the photocarriers, thus leading to superb photocatalytic ability. This work emerges an efficient route to design S-scheme heterojunction Bi2WO6-based photocatalytic methods for energy conversion and environmental purification.

Separation of small extracellular vesicles (sEV) from human blood by Superose 6 size exclusion chromatography.

Extracellular vesicles (EVs) are valuable targets for liquid biopsy. However, attempts to introduce EV-based biomarkers into clinical practice have not been successful to the extent expected. One of the reasons for this failure is the lack of reliable methods for EV baseline purification from complex biofluids, such as cell-free plasma or serum. Because available one-step approaches for EV isolation are insufficient to purify EVs, the majority of studies on clinical samples were performed either on a mixture of EVs and lipoproteins, whilst the real number of EVs and their individual specific biomarker content remained elusive, or on a low number of samples of sufficient volume to allow elaborate 2-step EV separation by size and density, resulting in a high purity but utmost low recovery. Here we introduce Fast Protein Liquid Chromatography (FPLC) using Superose 6 as a matrix to obtain small EVs from biofluids that are almost free of soluble proteins and lipoproteins. Along with theestimation of a realistic number of small EVs in human samples, we show temporal resolution of the effect of theduration of postprandial phase on the proportion of lipoproteins in purified EVs, suggesting acceptable time frames additionally to the recommendation to use fasting samples for human studies. Furthermore, we assessed a potential value of pure EVs for liquid biopsy, exemplarily examining EV- and tumour-biomarkers in pure FPLC-derived fractions isolated from the serum of patients with pancreatic cancer. Consistent among different techniques, showed the presence of diseases-associated biomarkers in pure EVs, supporting the feasibility of using single-vesicle analysis for liquid biopsy.

Hydrogen Separation Membranes: A Material Perspective

The global energy market is shifting toward renewable, sustainable, and low-carbon hydrogen energy due to global environmental issues, such as rising carbon dioxide emissions, climate change, and global warming. Currently, a majority of hydrogen demands are achieved by steam methane reforming and other conventional processes, which, again, are very carbon-intensive methods, and the hydrogen produced by them needs to be purified prior to their application. Hence, researchers are continuously endeavoring to develop sustainable and efficient methods for hydrogen generation and purification. Membrane-based gas-separation technologies were proven to be more efficient than conventional technologies. This review explores the transition from conventional separation techniques, such as pressure swing adsorption and cryogenic distillation, to advanced membrane-based technologies with high selectivity and efficiency for hydrogen purification. Major emphasis is placed on various membrane materials and their corresponding membrane performance. First, we discuss various metal membranes, including dense, alloyed, and amorphous metal membranes, which exhibit high hydrogen solubility and selectivity. Further, various inorganic membranes, such as zeolites, silica, and CMSMs, are also discussed. Major emphasis is placed on the development of polymeric materials and membranes for the selective separation of hydrogen from CH4, CO2, and N2. In addition, cutting-edge mixed-matrix membranes are also delineated, which involve the incorporation of inorganic fillers to improve performance. This review provides a comprehensive overview of advancements in gas-separation membranes and membrane materials in terms of hydrogen selectivity, permeability, and durability in practical applications. By analyzing various conventional and advanced technologies, this review provides a comprehensive material perspective on hydrogen separation membranes, thereby endorsing hydrogen energy for a sustainable future.

Toxicological and mechanistic insights into organic contaminants released from on-line membrane cleaning during ultrafiltration of algal-containing waters

Eutrophication has significantly challenged the treatment of algae-contaminated water. Ultrafiltration has become an essential method for water purification, though frequent on-line chemical cleaning is necessary to maintain membrane permeability. This study aims to systematically investigate the impact of various chemical cleaning agents on the release of dissolved organic matters and toxic by-products, particularly from algal cells. Through a series of controlled experiments, Microcystis aeruginosa cells were exposed to different cleaning agents (HCl, NaOH, NaClO), and the resulting DOM and by-products were characterized. Special attention was paid to the release of intracellular organic matter (IOM) and extracellular organic matter (EOM). Results revealed that NaClO significantly oxidized IOM, leading to the formation of humic-like substances and halogenated organic compounds (TOX), including 15 types of halogenated by-products detected by UPLC/ESI-tqMS. Furthermore, the release of toxic microcystin LR (MC-LR) was traced primarily to IOM. The removability of these contaminants by UF and reverse osmosis (RO) membranes was analyzed, revealing that over 50% of the toxic by-products passed through UF membranes, and 10% still penetrated RO membranes, raising significant concerns for downstream water quality and drinking water safety.

Zeolite-based absorbent: Polyacrylic acid loading for enhanced ferric(III) removal from aqueous solution

The process of adsorption shows promise as an effective method for water purification due to its cost-effectiveness, reusability, and adaptability in treating various metal ions. However, it has been noted that this method has limited Fe(III) removal capacity and is susceptible to interference from co-existing ions. To address this, a new adsorbent material (ZEO-PAA) was developed by loading polyacrylic acid (PAA) onto NaOH-treated zeolite using γ-Glycidoxypropyltrimethoxysilane (GPTMS) as a linker. In comparison to natural zeolite, ZEO-PAA demonstrates a strong affinity for Fe(III), exhibiting remarkable Fe(III) removal performance even in the presence of other common cations, such as Na(I), Ca(II), and Mg(II). Furthermore, ZEO-PAA maintains high adsorption performance for heavy metal ions such as Pb(II), Cu(II), Ni(II), Cd(II), and Cr(III). After 7 cycles of adsorption/regeneration, the Fe(III) removal rate of ZEO-PAA remains over 85 %. The adsorption process of ZEO-PAA for Fe(III) aligns with the Langmuir isotherm model and PSO Kinetics model, with a maximum adsorption capacity (qm) of 37.53 mg/g. This study provides valuable insights into the development of a reusable adsorbent material, demonstrating great potential for practical water treatment.

Hierarchical Ti3C2Tx MXene@Honeycomb nanocomposite with high energy efficiency for solar water desalination

The utilization of solar-driven interfacial evaporation holds immense promise in enhancing energy efficiency and establishing sustainable methods for seawater desalination and water purification. While designing the materials to achieve high evaporation efficiency, the tuning of materials with porosity and surface chemistry is very crucial. Novel sustainable materials are of great importance for solar water desalination applications since clean water production is utmost important in the current era. There exists a lack of exploration in modifying the surface wettability states of solar evaporators to expedite the vapor generation rates. In this study, we showcase a hydrophilic Ti3C2Tx MXene-coated carbonized honeycomb (CHC) (Ti3C2Tx MXene@CHC) nanocomposite-based hexagonal-shaped evaporator surface. This is the first-time report on the effective utilization of hierarchical CHC for the preparation of solar absorber comprising of Ti3C2Tx MXene@CHC nanocomposite, particularly for the solar water desalination. The Ti3C2Tx MXene@CHC nanocomposite evaporator achieves an impressive water evaporation rate of 1.6 kg m−2 h−1 with 90% efficiency under 1 sun illumination. The augmented thickness of the water layer in the hydrophilic surface of the Ti3C2Tx MXene@CHC nanocomposite helps in facilitating the rapid escape of water molecules. The relatively elongated contact lines in the hydrophobic region simultaneously ensure substantial water evaporation, significantly enhancing the water desalination process. The Ti3C2Tx MXene@CHC nanocomposite exceeds stringent quality benchmarks, signaling its potential for solar water desalination.

Coupling crossflow microfiltration and nanofiltration for the concentration of aroma compounds in a raspberry hydroalcoholic extract

AbstractThis work investigated the coupling of microfiltration (MF) and nanofiltration (NF) to concentrate the volatile compounds in a raspberry hydroalcoholic extract. Enzymatic treatment increased the MF permeate flux by 30%–50%. The highest MF permeate flux was above 50 kg·h−1·m−2 at a mass reduction ratio of 5. MF allowed efficient clarification of the extract without significant retention of aroma compounds. Among the NF membranes tested using the MF permeate as feed, one membrane was clearly more effective in concentrating the extract in terms of flux (19 kg·h−1·m−2 at 35 bar), retention of aroma compounds (average retention of 85%), phenolic compounds (61%) and dry matter (90%). Three other membranes were of interest for the fractionation of volatiles in both permeate and retentate but with a lower permeate flux. Finally, one membrane retained few aroma compounds but showed 70% dry matter retention, making it a promising method for aroma purification versus dry matter content in the permeate.Practical ApplicationsIn this study, we investigated the coupling of crossflow MF and NF with a pectinolytic pretreatment, in order to concentrate the aroma compounds from a raw organic raspberry extract. The aim was to avoid aroma degradation and reduce the operating costs, compared to the conventional concentration thermal technologies. Few authors have studied aroma concentration by NF, which presents an interesting area of research for industrial applications. This work provides keys for flavor manufacturers to add value to their products at a low cost and with limited environmental impact, producing concentrated natural aroma extracts for food. Another originality of this work for industrial companies was to show that thanks to the same process, several fractionations could be achieved simply by modifying the operating conditions. Therefore, this work contributed to propose new applicable processing for the production of natural flavors in a context of high consumer and market demand for organic ingredients.

Highly pure measles virus generated by combination of salt-active nuclease treatment and heparin affinity chromatography

Highly purified virus preparations are essential for accurate activity and potency determination. This requires simple and efficient purification methods, especially in the early stages of research and development. While heparin affinity chromatography has been already successfully used for the purification of several enveloped viruses and virus-like particles, we extended its use to purification of very sensitive measles virus. The performance of heparin and heparin-like affinity chromatography was evaluated for the purification of recombinant measles virus, a large and labile enveloped virus used as vaccine or cancer therapy. Since DNA, particularly in the form of chromatin is a critical impurity in enveloped virus preparations, the effect of integration of an endonuclease (Benzonase® or M-SAN) treatment prior to chromatography was also investigated.Both, Capto™ DeVirS (heparin-like) and Capto™ Heparin were able to capture measles viruses directly from clarified cell culture supernatant. Despite capturing 100% of infectious measles virus, low recovery (8%) was observed for Capto™ DeVirS. For Capto™ Heparin recoveries up to 85% were observed. The combination of M-SAN with Capto™ Heparin enabled the production of highly purified measles virus with a yield of 62% and a final purity of 10.2 ng dsDNA per dose (1×105), outperforming the processes without endonuclease treatment with a yield of 18%, and a purity of 66.7 ng dsDNA/dose or using Benzonase® with a yield of 38% and a purity of 21.2 ng dsDNA/dose. As the developed method is simple and scalable it could also be integrated in a downstream process train for measles virus manufacturing.

Photodegradation of RB5 dye with modified zeolites: influence of temperature and UV irradiation

Abstract This study explores the photocatalytic degradation of Reactive Black 5 (RB5) dye using thermally modified natural zeolites, aiming to improve water purification methods. Zeolites were calcined at 250 °C, 350 °C, and 500 °C, and characterized through x–ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) to analyze their structural and morphological transformations. The results reveal that calcination significantly enhances the photocatalytic performance, particularly for ZNM500, which exhibited the highest efficiency, reaching a 60% removal rate of RB5. The degradation process follows a pseudo-first-order kinetic model at lower dye concentrations but adheres more closely to the Langmuir–Hinshelwood equation at higher concentrations, emphasizing the role of surface adsorption in catalysis. UV irradiation was a key factor in boosting reaction rates, with shorter wavelengths (254 nm) providing greater energy, leading to more effective dye breakdown by facilitating the generation of reactive hydroxyl radicals (·OH). These findings suggest that thermally modified zeolites, especially ZNM500, represent a promising solution for wastewater treatment, offering an efficient, cost–effective, and environmentally friendly approach to removing synthetic dyes from contaminated water sources.

Expanding sample volume for microscopical detection of nanoplastics

The extent of nanoplastic pollution has raised severe environmental and health concerns. While the means for microplastic detection are abundant, improved tools for nanoplastic detection are called-for. State-of-the-art microscopic techniques can detect nanoplastics down to tens of nanometers, however, only from small sample sizes (typically ∼10μl). In this work, we describe a method that enables sampling of 1 liter of seawater by the means of correlative Raman- and SEM-techniques. This is achieved by adapting common microplastic sample purification protocols to suit the nanoplastic study. In addition, we decorate a membrane filter with SERS-property to amplify the Raman signals. Together, the purification method combined with the use of the SERS-activated-membrane-filter enables identification and imaging of individual nanoplastic particles from significantly larger sample sizes than before. In the nanoscale the average recovery rate is 5 %. These results aim to provide useful tools for researchers in the fight against plastic pollution.

Ultrafast continuous flow-dialysis for nanoparticle-based drug delivery systems via microfluidic-multiple buffer injector

Nanoparticle-based drug delivery systems (NP-DDS) have emerged as promising carriers for bioactive organic molecules due to their potential in enhancing therapeutic effects. However, traditional purification methods like batch dialysis and diafiltration can alter NP-DDS bio-physicochemical properties due to the lengthy process, prolonged coexistence with organic solvents, and external forces. To address this challenge, we developed an ultrafast flow-dialysis microfluidic module with dual channels separated by a membrane layer. The module leverages multiple buffer injectors (MBIs) to accelerate dialysis by injecting fresh buffer into multiple dialysis zones of bottom channel, refreshing the concentration gradients over the mixture sample in the upper channel to maximize mass transfer efficiency. Using this method for a dual drug-loaded liposome sample containing doxorubicin and curcumin, impurities (such as ethanol and un-trapped drugs) removal and buffer exchange were rapidly terminated within 15 min, continuously operating for ∼ 6 hrs with sequential membrane regeneration process. Importantly, unlike traditional methods, the MBI process maintains the initial uniformity in the size and distribution of liposomes with no leakage of the encapsulated drugs. In vitro HeLa cell tests reveal that the liposomes purified by MBI exhibited significantly higher cellular uptake (1.13 ∼ 1.67 fold), presumably due to the small and uniform size of liposomes, leading to improved anti-tumor effects. Notably, the MBI platform’s versatility was further verified by purifying a mixture of laccase enzyme and by removing the used organic solvents from various carriers (e.g., lipid-based, polymeric, and protein nanoparticles). It is envisioned that the outstanding performance of ultrafast dialysis will enables a continuous-flow downstream process for diverse nano-carriers by intensifying with extra steps in the manufacturing of nanomedicnes, including targeted drug delivery and cancer therapy.

Analysis of the antigenic and immunogenic properties of the native rabies virus glycoprotein purified by Lens culinaris lectin affinity chromatography

Rabies virus glycoprotein (RABV-G) is responsible for the recognition of specific cell surface receptors and induces the production of neutralizing antibodies (VNA). Since RABV-G is a glycoprotein, this work aimed to evaluate Lens culinaris (LCA) chromatography as a simple and effective purification method. The purity and identification of the protein obtained were analyzed by SDS-PAGE, ELISA and lectin-binding assay. The antigenic properties of the purified RABV-G were evaluated by direct ELISA using human serum samples from individuals who had received rabies pre-exposurevaccination. For the immunogenicity study, Swiss Webster mice were immunized with purified RABV-G and the specific antibodies were measured by direct ELISA and RFFIT. As results, it was observed that the purified protein reveled a molecular mass of 55 KDa and the presence of carbohydrate; additionally, it was recognized by anti-rabies virus glycoprotein monoclonal antibody. Purified RABV-G induced high VNA titers (>50.0 IU/ml) in vivo, as detected by RFFIT, as well as RABV-G specific IgG1 (0.8 mean OD±SD) and IgG2a (0.3 mean OD±SD) antibodies, with a predominance of IgG1 (p< 0.001). In addition, it was observed that RABV-G was efficient in selectively detecting anti- RABV-G IgG in the sera of vaccinated individuals compared to the negative control. Therefore, LCA chromatography was efficient in preserving the native properties of RABV-G that are essential in inducing an adequate humoral immune response. In addition, the purified RABV-G presented analytical potential as an ELISA reagent.

Очистка торфяных грунтовых вод методом ультрафильтрации и ионного обмена

Purpose: assessing the effectiveness of peat groundwater purification using a combination of two methods of ultrafiltration and membrane purification. Identify specific characteristics of the composition of peat or groundwater, determine possible possible methods of treating these waters to ensure compliance with the requirements of SanPiN 2.1.3684–21 “Sanitary and epidemiological requirements for the maintenance of territories of urban and rural settlements, for water bodies, drinking water and drinking water supply to the population, atmospheric air, soil, residential premises, operation of industrial and public premises, organization and implementation of sanitary and anti-epidemic (preventive) measures” to the quality of drinking water. Determine the list of composition indicators that require cleaning. Conduct an assessment of wastewater treatment methods used to treat peat groundwater. Togo, Conduct research on the composition of purified groundwater before and after treatment, determine the effectiveness of the treatment methods used according to various indicators. Determination of the concentrations of groundwater composition components was carried out using approved methods in accordance with GOST R 57164-2010 clause 5; GOST R 57164-2010 clause 6; PND F 14.1:2:4.207-04; PND F 14.1.2:3:4.121-97; PND F 14.1:2:4.114-97; GOST 31594-2012 Method A; PND F 14.1:2:4.50-96; PND F 14.1.2:3:4.111-97; PND F 14.1.2:3:4.111- 97; PND F 14.1.2:3.154-99; PND F 14.1.2:3:4.123-97; GOST 31859-2012; PND F 14.1.2:3:4.4-95; GOST 31940-2012 clause 6; PND F 14.1.2:4.178-02; PND F 14.1.2:4.214-06. An analysis of the results of laboratory studies of the composition of peat groundwater before and after treatment was carried out, and the effectiveness of ultrafiltration and membrane water purification methods was determined. The results of studies of the effectiveness of purification of peat groundwater using ultrafiltration and membrane purification methods show that purified groundwater meets the sanitary and epidemiological requirements for the quality of drinking and domestic water supply established by SanPiN 2.1.3684-21. Practical significance: the results obtained from studies of the effectiveness of peat groundwater treatment using ultrafiltration and membrane treatment methods indicate the possibility of using these methods, because they ensure that water quality meets the requirements of SanPiN 2.1.3684-21.

STUDY OF THE BEHAVIOR OF ARSENIC IN COPPER ELECTROLYTE

Abstract. In industrial wastewater, arsenic is most often present in the trivalent state. An analysis of existing purification methods shows that in all cases, with a few exceptions, the most complete removal of arsenic is observed from solutions in which it is in the pentavalent state. This is explained by the significantly lower solubility of arsenates of heavy and alkaline earth metals compared to the corresponding arsenites. The chemical oxidation of As(III) in the following systems was studied: As(III)-H2SO4-H2O, As(III)-MeSO4-H2O, As(III)–H2SO4–MeSO4–H2O (where Me is Cu, Ni, Co, Mn, Zn). The influence of temperature, the amount of transition metal ions, the duration of the experiment, and the concentration of sulfuric acid on the degree of transition of As(III) to As(V) was studied. The effect of catalytic oxidation of As(III) in sulfuric acid solutions was discovered. The maximum degree of oxidation of trivalent arsenic (55-60%) is observed when transition metal salts are introduced into an arsenic solution in the presence of a platinum plate. It has been established that the nature of the studied transition metal salts (Cu2+, Ni2+, Co2+, Mn2+, Zn2+), process duration and temperature do not have a significant effect on the degree of As(III) conversion. The results obtained largely explain the predominance of pentavalent forms of arsenic in production solutions of non-ferrous metallurgy. Key words: copper electrolyte, arsenic, transition metals, catalytic role, instant oxidation effect, activated oxygen.

Graphene Quantum Dots from Natural Carbon Sources for Drug and Gene Delivery in Cancer Treatment

Cancer therapy is constantly evolving, with a growing emphasis on targeted and efficient treatment options. In this context, graphene quantum dots (GQDs) have emerged as promising agents for precise drug and gene delivery due to their unique attributes, such as high surface area, photoluminescence, up-conversion photoluminescence, and biocompatibility. GQDs can damage cancer cells and exhibit intrinsic photothermal conversion and singlet oxygen generation efficiency under specific light irradiation, enhancing their effectiveness. They serve as direct therapeutic agents and versatile drug delivery platforms capable of being easily functionalized with various targeting molecules and therapeutic agents. However, challenges such as achieving uniform size and morphology, precise bandgap engineering, and scalability, along with minimizing cytotoxicity and the environmental impact of their production, must be addressed. Additionally, there is a need for a more comprehensive understanding of cellular mechanisms and drug release processes, as well as improved purification methods. Integrating GQDs into existing drug delivery systems enhances the efficacy of traditional treatments, offering more efficient and less invasive options for cancer patients. This review highlights the transformative potential of GQDs in cancer therapy while acknowledging the challenges that researchers must overcome for broader application.

Effect of Different Blood Purification Methods on Residual Renal Function in Maintenance Hemodialysis Patients

Objective: This study aims to evaluate the efficacy of different blood purification methods in protecting residual renal function (RRF) in patients with maintenance hemodialysis (MHD). Methods: The study selected 50 patients receiving MHD between September 2023 and September 2024. Using the random number table method, patients were divided into the control group and the study group, each with 25 participants. The control group received hemodiafiltration, while the study group was treated with hemodialysis plus hemoperfusion. The RRF measures of the two groups were compared. Results: There were significant differences in the RRF measures (P &lt; 0.05). Conclusion: Combined hemodialysis and hemoperfusion therapy can effectively improve the RRF index of MHD patients with a significant curative effect.

Continuous Microreactor‐Based Synthesis of SnO2 Nanoparticles for Sensor Applications

Tin oxide nanoparticles are well‐established materials with a wide range of applications, including optoelectronic devices and solid‐state gas sensors. Conventional synthesis methods of these systems are often based on batch processes. In this study, we compare batch and continuous synthesis methods for tin dioxide nanoparticles using precipitation and sol‐gel processes. For the continuous processes we applied the so called microjet reactor method. The nanoparticles were characterized by TEM, elemental analysis and XRD and exhibited particle sizes of 1.7‐3.0 nm and crystallite sizes of 1.7‐2.3 nm, consisting of tetragonal (P42/mnm) and orthorhombic (Pbcn) phases. We have evaluated different post‐synthesis purification methods to remove impurities such as chlorides and carbon‐hydrogen species. Each purification method exhibited unique advantages and side effects, providing insight into selecting the most appropriate method for specific applications. We also demonstrated the potential of these SnO2 nanoparticles as ethanol gas sensing materials and compared their performance with a commercial sensor.