Search Results (240)

This study developed and validated a stability-indicating high-performance thin-layer chromatography (HPTLC) method for the identification and quantification of gentamicin sulphate in an ointment formulation using silica gel 60 F254 HPTLC plates as the stationary phase and methanol: chloroform: ammonia solution (25%) (1:1:1, v/v/v) as the mobile phase. An ideal solvent ratio, chloroform: methanol (9:1, v/v), was used to dissolve the ointment sample before analysis. According to the guidelines of the International Council for Harmonisation (ICH), the HPTLC method was validated, demonstrating specificity by separating all three bands of gentamicin sulphate without interference from ointment excipients and/or degradation products resulting from photolytic, photolytic and oxidative, oxidative, acidic, and alkaline stress conditions. The findings of the study also revealed that the method has high levels of linearity within the range of 50–300 ng/band (R² ≥ 0.99), with detection and quantification limits of 7.10 ng, and 21.53 ng, respectively. Additionally, the method does not require any sample pre-treatment, such as extraction from the ointment base, making it simple and convenient for the quality control of gentamicin ointments. Full article

Background/Objectives: Adeno-associated viruses (AAVs) are widely used gene therapy vectors; yet their physicochemical stability and chromatographic behavior are highly sensitive to the solution conditions they are in. Effective separation of full (F), empty (E), and partially filled (P) capsids—most commonly achieved by anion exchange (AEX) chromatography—is essential for standard analytical characterization, process development, and product safety. However, conventional AEX methods rely on low-conductivity alkaline mobile phases with low salt, which promote capsid binding and therefore higher resolution, at the expense of structural stability. Conversely, formulations such as near-neutral buffers might preserve capsid integrity but often impair AEX retention and separation resolution. Methods: Here, we extend a mechanistic investigation using AAV8 capsids as a model system, focusing on detailed capsid interactions with strong AEX, and present novel AAV8 separation strategies on a weak AEX stationary phase. Results: By systematically varying buffer pH and ionic strength, we identify operational regimes that balance capsid stability with chromatographic separation efficiency. In parallel, we introduce an integrated two-dimensional (2D) in-line buffer exchange configuration that decouples AEX performance from sample formulation, enabling robust separation of stability-optimized, high-salt matrices without off-line desalting. Conclusions: By elucidating the roles of capsid charge modulation, ligand physicochemical properties, and local microenvironmental buffering, this study establishes practical design principles for stability-preserving chromatography. It lays a foundation for more reliable analytical and future preparative AAV workflows. Full article

Phosphate-solubilizing bacteria (PSB) are pivotal in the cycling of phosphorus within terrestrial ecosystems and hold great promise for sustainable agriculture. In this study, we report the isolation of HRY1—a highly efficient phosphate-solubilizing strain—identified as Escherichia coli, a bacterium not traditionally recognized for plant-beneficial traits. Under optimized conditions (glucose as carbon source, (NH₄)₂SO₄ as nitrogen source, pH 7.0, 1% inoculum, and 5 g/L Ca₃(PO₄)₂), HRY1 consistently solubilized ~16% of inorganic phosphorus, with peak activity coinciding with its stationary growth phase (14 h). Whole-genome sequencing revealed a comprehensive genetic toolkit for phosphorus mobilization, including eight genes implicated in organic acid-mediated mineral dissolution, five high-affinity phosphate transporter genes (pit and pst gene cluster), and three two-component regulatory systems responsive to phosphate starvation (e.g., phoBR). The functional integration of these systems suggests a multifaceted strategy combining acidification, active uptake, and adaptive regulation to thrive under phosphorus limitation. Our findings redefine the ecological scope of E. coli and uncover an unconventional yet potent PSB candidate with significant potential for biofertilizer development and soil phosphorus activation. This discovery reveals E. coli’s untapped potential for phosphorus solubilization, with HRY1’s novelty residing in its high efficiency under optimized conditions and its practical promise as a biofertilizer. Full article

This study aimed to develop and validate a rapid and robust reverse-phase high-performance liquid chromatography assay for amiodarone, creating an alternative to the previously established pharmacopeial method (retention time: 26 min). For method optimization, 20 mM of triethylamine (TEA) was added to the mobile phase buffer, followed by adjusting the organic solvent ratio and using a C18 column as the stationary phase. Under the optimized analytical conditions, the retention time of amiodarone was 5.51 min, which represents a reduction of approximately 80% compared to the previous method. Following the ICH Q2 guideline, the developed method was validated for key performance characteristics, including system suitability, specificity, linearity, accuracy, precision, and robustness. The method showed high linearity with a correlation coefficient (R² > 0.999) across a concentration range of 0.06–0.14 mg/mL (representing 60–140% of the target concentration of 0.1 mg/mL). The analytical method developed in this study significantly reduces analysis time and costs while providing reproducible results. Therefore, it is expected to be highly useful as a routine quality control test for amiodarone generic drug products. Full article

The use of white-rot fungi Pleurotus spp. and Trametes versicolor in continuous-flow fixed-bed systems has emerged as a promising and sustainable approach for the removal of different pollutants from aqueous media. This overview presents the most important design and operating parameters, the efficiency of fixed-bed systems using these fungi and their spent substrate, and the effect of operating parameters on changes in removal efficiency. After a literature screening based on the Scopus database, the overview focuses specifically on 55 studies that present the results of several hundred tests, meeting the criteria for continuous-flow fixed-bed systems, which include ensuring uninterrupted flow, constant adsorbent mass, and continuous interaction between the stationary and mobile phases. Results reported in the literature show the varying importance of biodegradation and biosorption processes in the removal of metals and organic pollutants (e.g., dyes, pharmaceuticals, pesticides, volatile compounds). The overview highlights the impact of operational parameters on removal efficiency, including bed depth, flow rate, type of polluted water, and initial concentration. It also determines that these fixed-bed systems using Pleurotus spp. and Trametes versicolor are primarily suitable for modelling the adsorption-based removal of given pollutants and the bioremediation of smaller amounts of municipal, industrial, or agricultural wastewater. Full article

Mid-sized Philippine cities commonly rely on fixed-time traffic signal plans that cannot respond to short-term, demand-driven surges, resulting in measurable idle time at stop lines, increased delay, and unnecessary emissions, while adaptive signal control has demonstrated performance benefits, many existing solutions depend on centralized infrastructure and high-bandwidth connectivity, limiting their applicability for resource-constrained local government units (LGUs). This study reports a field deployment of TrafficEZ, a lightweight edge AI signal controller that reallocates green splits locally using traffic-density approximations derived from cabinet-mounted cameras. The controller follows a macroscopic, cycle-level control abstraction consistent with Transportation System Models (TSMs) and does not rely on stationary flow–density–speed (fundamental diagram) assumptions. The system estimates queued demand and discharge efficiency on-device and updates green time each cycle without altering cycle length, intergreen intervals, or pedestrian safety timings. A quasi-experimental pre–post evaluation was conducted at three signalized intersections in El Salvador City using an existing 125 s, three-phase fixed-time plan as the baseline. Observed field results show average per-vehicle delay reductions of 18–32%, with reclaimed effective green translating into approximately 50–200 additional vehicles per hour served at the busiest approaches. Box-occupancy durations shortened, indicating reduced spillback risk, while conservative idle-time estimates imply corresponding CO₂ savings during peak periods. Because all decisions run locally within the signal cabinet, operation remained robust during backhaul interruptions and supported incremental, intersection-by-intersection deployment; per-cycle actions were logged to support auditability and governance reporting. These findings demonstrate that density-driven edge AI can deliver practical mobility, reliability, and sustainability gains for LGUs while supporting evidence-based governance and performance reporting. Full article

Many polar compounds of biochemical and pharmaceutical relevance exhibit low retention in reversed-phase liquid chromatography (RPLC), making their separation challenging. While hydrophilic interaction liquid chromatography (HILIC) columns are commonly used for such analyses, they require mobile phases with high organic solvent content. This work explores an alternative approach using RPLC with conventional C18 columns and mobile phases containing low percentages of acetonitrile, along with small amounts of the surfactant sodium dodecyl sulfate (SDS). This combination significantly enhances the retention of highly polar compounds. When the SDS concentration is sufficiently low, below the critical micellar concentration in water (8 mM), the retention increase follows a linear pattern. The retention behavior of polar compounds with different properties (nucleosides, methylxanthines, sulfonamides, and the diuretic hydrochlorothiazide) is examined using mobile phases in the submicellar region, with SDS concentrations ranging from 0 to 0.3 mM, acetonitrile contents between 10 and 20% (v/v), and temperatures varying from 25 to 55 °C. Changes in peak half-widths are also analyzed. Since SDS adsorbs onto the stationary phase, modifying its surface, the equilibration time has been investigated as a critical factor affecting retention reproducibility, influenced by the SDS concentration, acetonitrile content, and temperature. The results emphasize the need for complete equilibration to ensure reliable and consistent results. Full article

Background/Objectives: Previously reported analyses show that some androstane-3-oxime derivatives with picolyl and picolinylidene functional groups possess a significant anticancer activity towards various cancer cell lines. These findings suggest that these compounds have prominent biological potential and represent a good basis for further research. The present study aims to determine their anisotropic lipophilicity as a physicochemical parameter relevant to both prediction of chromatographic behavior and biological activity. Methods: Anisotropic lipophilicity was determined using reversed-phase ultra-high performance liquid chromatography (RP-UHPLC) systems equipped with three stationary phases (C18, C8 and phenyl) and three mobile phases composed of water with different modifiers (methanol, acetonitrile and a methanol-acetonitrile mixture). Capacity factors (logk) were obtained for all compounds across the chromatographic systems to describe their behavior in anisotropic environments. Chemometric analyses were performed using linear pattern recognition techniques (PRT), such as hierarchical cluster analysis (HCA) and principal component analysis (PCA), and non-linear clustering based on artificial neural networks (CANN). Results: The experimentally determined chromatographic parameters were correlated with in silico lipophilicity values (logP). This comparison allowed for examination of the concordance between experimental and computed data for the series of androstanes. The chemometric analysis resulted in models that provided an overview of the grouping of compounds in the space of the determined chromatographic parameters. Conclusions: The results demonstrate strong agreement between experimental and computational lipophilicity parameters. This very good data fit provides a reliable foundation for further studies exploring the relationships between lipophilicity and biological activity of the studied androstane derivatives. Full article

This study was designed for the analytical method development and validation for Calcium butyrate (CAB) using High-Performance Liquid Chromatography (HPLC). ¹H and ¹³C Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy analysis were carried out to examine the molecular structure. For HPLC analysis, a blend of acetonitrile and phosphoric acid solution (0.1%) (20:80) (v/v) was used as a mobile phase. A C18 column (5 µm, 250 × 4.6 mm) was used as a stationary phase. The eluent of CAB was monitored with a UV detector at a wavelength of 206 nm and a flow rate of 1 mL/min. According to the results, FTIR and NMR spectra were consistent with the structural characteristics of CAB, and the expected proton and carbon signals were observed. During the HPLC analysis, due to the ionization of CAB, three distinct retention times were observed in the chromatograms at 3.4, 4.5, and 7.4 min. The validation was performed according to ICH guidelines. The obtained results demonstrated that the analytical method was successfully validated, with LOD values of 1.211, 0.606, and 1.816 µg/mL, and LOQ values of 3.670, 1.835, and 3.676 µg/mL. The assay displayed a linear range of 5–1000 µg/L concentration and was found suitable for further formulation content analysis. Full article

Vulnerability is often analysed as a static condition of residents at a location, exposed to disaster and other risks. Studies on individual aspects of mobility and vulnerability exist, but comprehensive studies or guiding frameworks are lacking. The paper’s unique contribution compared to existing vulnerability models lies in emphasising vulnerability not only at fixed places, but also during transit, movement, and temporary phases. This paper highlights the current state of research on mobility vulnerability within disaster risk contexts. Through a systematic literature review, the study discovers a lack of research analysing specific vulnerabilities during mobility. Additionally, existing vulnerability frameworks are improved by incorporating (i) disaster risk and impact scenarios, (ii) different types of movements and mobilities linked to disaster risk situations, (iii) multiple localities, modalities, and temporalities, as well as multiple risks during sequences of movement and stationary phases, (iv) daily and occasional hazards, and (v) emic and etic perspectives on vulnerability. The findings of this study aim to inform future research on risk and vulnerability, supporting more effective responses amidst the changing dynamics of disaster situations. Full article

Background: Compound lipophilicity is a fundamental physicochemical property for determining the pharmacokinetic and pharmacodynamic profiles of therapeutic substances. It is successfully used in the early stages of drug candidates’ design and development. Aim: Taking into account the importance of this parameter, we aimed to assess and compare the utility of a hybrid procedure based on calculation methods and an experimental one for rapid and simple estimation of the lipophilicity of selected neuroleptics such as fluphenazine, triflupromazine, trifluoperazine, flupentixol and zuclopenthixol and their potential new derivatives. Methods: Log P values of the studied compounds were predicted by means of different platforms and algorithms: AlogPs, ilogP, XlogP3, WlogP, MlogP, milogP, logPsilicos-it, logP_consensus, logP_chemaxon and logP_ACD/Labs. The experimental determination of lipophilicity was carried out by reverse-phase thin-layer chromatography (RP-TLC) using three types of stationary phases—RP-2F₂₅₄, RP-8F₂₅₄ and RP-18F₂₅₄—and mobile phases consisted of acetone, acetonitrile and 1,4-dioxane as organic modifiers. Results: Our results provide a confident proposal of optimal chromatographic conditions to experimentally determine the lipophilicity of neuroleptic drugs, including new derivatives. Conclusions: Additionally, for the first time, the paper shows the application of selected topological indices in determining lipophilicity factors and other ADMET parameters of neuroleptics and, in the future, the newly synthesized quinoline derivatives of the studied compounds. Full article

Olive leaves, the main byproducts of olive cultivation, are characterized by a plethora of bioactive metabolites with significant nutritional value. Their main pentacyclic triterpenes, Oleanolic Acid (OA) and Maslinic Acid (MA), are two high added-value compounds with remarkable activities. This study aimed to develop an efficient methodology for extracting and purifying OA and MA, utilizing Supercritical Fluid Extraction (SFE) and Centrifugal Partition Chromatography (CPC)—two modern, scalable, and green techniques. A total of 21 g of olive leaves were subjected to SFE using supercritical CO₂ and ethanol as co-solvent. The extraction employed a step gradient mode, starting with 100% CO₂ and incrementally increasing ethanol (0–10% w/w) every 20 min. Fractions rich in OA and MA (500 mg) were further purified via CPC, utilizing pH zone refining to exploit the protonation and deprotonation properties of acidic triterpenes. The biphasic solvent system consisted of n-hexane, ethyl acetate, ethanol, and water (8:2:5:5 v/v/v/v), with trifluoroacetic acid added to the stationary phase and triethylamine added to the mobile phase. This two-step process yielded 89.5 mg of OA and 28.5 mg of MA with over 95% purity, as confirmed by HPLC-ELSD and ¹H-NMR. Moreover, purified compounds and SFE fractions exhibited promising elastase and collagenase inhibition, highlighting them as dermocosmetic agents. Full article

β-carotene, a high-value carotenoid widely used in the food, pharmaceutical, and cosmetics industries, is naturally synthesized by the microalga Dunaliella sp. However, the efficient extraction and purification of β-carotene from microalgae biomass remain a technical challenge. This study presents the development of a scalable and efficient isolation method employing high-performance countercurrent chromatography (HPCCC) to recover β-carotene from Dunaliella sp. The separation process was optimized by integrating two elution strategies (reverse phase and extrusion) using a biphasic solvent system of n-heptane and methanol (1:1, v/v). The upper phase served as the stationary phase, while the lower phase was used as the mobile phase. Two consecutive injections of 800 mg of microalgal extract each resulted in the isolation of 225.4 mg of β-carotene with a purity of 97% and a recovery of 98%. The developed HPCCC approach represents an efficient method for β-carotene purification and serves as a promising model for future scale-up in microalgae-based production platforms. Full article

The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary phase (hydrophobic stationary phase, C18 and strong cation exchanger (SCX)) was our first choice. Design of Experiments (DoE) was used to estimate how various factors such as pH, mobile phase composition and flow rate influenced chromatographic performance. As a result, the separation was achieved in 24 min using an aqueous phosphate buffer phase (pH 7.20) and 20 mM triethylamine, with methanol being used as organic modifier (30%). Their retention mechanism was investigated. The new method was validated in term of linearity, limits of detection and quantification, precision, accuracy, and robustness. The method was applied to river water samples, and good results were obtained. Full article

The evaluation of the time spent by a solute exclusively in the mobile phase (dead time) is of fundamental interest for the interpretation of the retention data and obtainment of thermodynamic parameters for the HPLC process. This parameter depends on the volume occupied by the mobile phase and on the volume of the effective stationary phase from the HPLC column, and the measurement of these volumes poses a real challenge. This review discusses the evaluation of volumes of various phases involved in the retention process of solutes, which are related to the dead time, and the phase ratio for the separation. This paper attempts to cover as many points of view as possible regarding this topic in liquid chromatography, which is of importance for almost all separation mechanisms. Full article