Vertical Diffusion Research Articles

Concurrence of Temperature and Humidity Inversions in Winter in Qingdao, China

AbstractConcurrence of temperature inversion (TI) and humidity inversion (HI) is a particular configuration of the atmospheric boundary layer with important implications for early warning of fog formation. With a microwave radiometer device deployed in a 2‐month winter campaign at a coastal island in Qingdao, China, we here examine the relationship between TI and HI, and investigate the underneath mechanisms. Cases of temperature inversion are further divided into surface‐based temperature inversion (SBTI) and elevated temperature inversion (ETI), which show different relationship with HI. SBTI typically occurs at night with its strength significantly and positively correlated with HI. ETI also shows a high degree of temporal overlap with HI, but its strength has no obvious relationship with HI. The main explanation for this phenomenon is that ETI may block the vertical diffusion of water vapor, resulting in the formation of HI.

Production and transfer of cosmogenous tritium in the Earth atmosphere in the «PARMA» model

The paper analyses contribution of reactions (n,X) and (p,X) on nitrogen and oxygen nuclei to the production and transfer of cosmogenic tritium in the Earth atmosphere. To calculate the fluxes of secondary protons and neutrons in the nuclear-electromagnetic cascade, the analytical model «PARMA» was used. The model is based on analytical approximations of both numerous experimental data and computer simulation data, and allows one to calculate the fluxes of various particles of secondary cosmic radiation (nucleons, muons, a- and b-particles) with the choice of a given energy range, atmospheric height, geomagnetic cutoff rigidity, solar activity. The problem of vertical turbulent diffusion of tritium in the Earth's atmosphere was solved and the dependence of its concentration on altitude was obtained. Numerical integration of the transport equations was carried out using the integro-interpolation method. An estimate of the total reserve of cosmogenic tritium in the Earth's atmosphere, balanced by turbulent diffusion, decay and cosmogenic formation, was given, which amounted to ~1.9∙1017 Bq. The calculation results show that the earth's atmosphere contains no more than 10% of all cosmogenic tritium. The results are generally consistent with earlier empirical and semi-empirical models confirming that man-made tritium currently accounts for the majority of the total tritium supply

A Validated IVRT Method to Evaluate Semisolid Dosage Form Containing Ximenynic Acid Using a Novel Approach

Purpose: Ximenynic acid (XMA) holds significant potential in the market, especially due to its widespread application in the cosmetics sector. As its various biological activities continue to be discovered, there is a sharp rise in demand for ximenynic acid. A novel analytical approach has been devised for an in-house product, comparable to the reference listed drug (Softalia, containing 30% ximenynic acid), utilized in gel formulations. This method is designed to conduct in-vitro release studies employing Franz vertical diffusion cell apparatus and analytical quantification via high-performance liquid chromatography (HPLC). Methods: The methodology has been assessed concerning specificity, linearity, the limit of quantitation (LoQ), limit of detection (LoD), inter-day precision, intermediate precision, accuracy, and solution stability. Following method development, the reference product containing 30% ximenynic acid underwent testing against the in-house XMA semisolid dosage form to accurately demonstrate “equivalence”, with results aligning with the applicable acceptance criteria falling within the range of 75 to 133.33%, as outlined in the FDA’s SUPAC-SS guidance. The in-vitro release assay has proven valuable for quality assurance, batch comparison, and monitoring the impacts of different formulations, scales, scaling up/down, methods, locations, and other variables. Results: This research fabricates specific IVRT techniques for performing assessments of semisolid dosage forms, which are required for many regulatory purposes.

The Modification of converting the basin liner to the reflector for vertical multiple-effect diffusion solar still coupled with basin still

ABSTRACT Vertical multiple-effect diffusion solar still (VMEDS) coupled with basin still (VMBS) consists of a triangular basin still and VMEDS. Distillation can be repeated by utilising the latent heat of condensation in VMEDS. The primary thermal input to VMEDS is direct solar radiation and latent heat of vapour evaporated from the basin liner and condensed on p1. However, VMEDS can hardly use the latent heat of vapour as a heat source during the winter season. To solve the problem, the conversion of the basin liner to a reflector is proposed and its effect was verified theoretically. The results show that thermal input to VMEDS can be increased by converting the basin liner to the reflector, and this can compensate for the disappearance of distillation in a basin still in winter. It was also predicted that the overall daily amount of distillate can be greater for modified VMBS than for conventional VMBS on the winter solstice.

On the contribution of the top and bottom walls in micro-pillar array columns and related high-aspect ratio chromatography systems

We report on a steady-state based, and hence highly accurate numerical modelling study of the effect of the top and bottom wall in the current generation of micro-pillar array columns. These have a mesoporous retention layer that not only covers the pillar walls but also the bottom wall. Our results show that the performance of these columns can in general not be improved by also covering the top wall with the same layer, despite the increased column symmetry this approach would offer. The reason for this is that the local species retardation caused by a retentive layer is much stronger than the pure flow arresting effect of an uncovered wall. At least, this has a crucial impact in high aspect-ratio systems such as micro-pillar array columns because these require a small inter-pillar distance to promote mass transfer together with a large channel depth to enable a sufficiently high flow rate. On the other hand, a notable improvement could be made if micro-pillar array would be produced without having a retentive layer at the bottom. At Péclet number Pe = 50 and aspect ratio AR = 5 for flow-channels, this gain amounts up to about 4.5 h-units at a zone retention factor k’’ = 2 and 1.75 h-units at k’’ = 16 (gain scales almost linearly with Pe).To verify these results, we also considered another high aspect-ratio system with a simplified geometry: the open-tubular channel with a flat-rectangular cross-section. This led to very similar observations, thus confirming the findings for the micro-pillar array.The results produced in the present study also allow us to conclude that the classic modelling paradigm adopted in chromatography, which is based on the independency and hence additivity of the hCm- and hCs-contributions, can lead to large modelling errors in chromatographic systems with a high aspect-ratio, even when their geometry is so simple as that of a straight open-tubular channel with constant cross-section. Indeed, when both zones are treated independently, the analysis misses how the vertical diffusion through the retentive layer helps suppressing the vertical gradients in the mobile zone. The diffusion through this layer occurs in a ratio of k’’Ds/Dm (Dm being the diffusion coefficient in mobile phase zone and Ds being the diffusion coefficient in stationary phase zone), such that at high retention factors this diffusion contribution even becomes the dominant one.

The Impact of Vertical Eddy Diffusivity Changes in the CMAQ Model on PM2.5 Concentration Variations in Northeast Asia: Focusing on the Seoul Metropolitan Area

The vertical eddy diffusion process plays a crucial role in PM2.5 prediction, yet accurately predicting it remains challenging. In the three-dimensional atmospheric chemistry transport model (3-D AQM) CMAQ, a parameter, Kz, is utilized, and it is known that PM2.5 prediction tendencies vary according to the floor value of this parameter (Kzmin). This study aims to examine prediction characteristics according to Kzmin values, targeting days exceeding the Korean air quality standards, and to derive appropriate Kzmin values for predicting PM2.5 concentrations in the DJFM Seoul Metropolitan Area (SMA). Kzmin values of 0.01, 0.5, 1.0, and 2.0, based on the model version and land cover, were applied as single values. Initially focusing on December 4th to 12th, 2020, the prediction characteristics were examined during periods of local and inflow influence. Results showed that in both periods, as Kzmin increased, surface concentrations over land decreased while those in the upper atmosphere increased, whereas over the sea, concentrations increased in both layers due to the influence of advection and diffusion without emissions. During the inflow period, the increase in vertically diffused pollutants led to increased inflow concentrations and affected contribution assessments. Long-term evaluations from December 2020 to March 2021 indicated that the prediction performance was superior when Kzmin was set to 0.01, but it was not significant for the upwind region (China). To improve trans-boundary effects, optimal values were applied differentially by region (0.01 for Korea, 1.0 for China, and 0.01 for other regions), resulting in significantly improved prediction performance with an R of 0.78, IOA of 0.88, and NMB of 0.7%. These findings highlight the significant influence of Kzmin values on winter season PM2.5 prediction tendencies in the SMA and underscore the need for considering differential application of optimal values by region when interpreting research and making policy decisions.

A numerical research on transient transport of high-temperature particles associated with air gouging process

The high-temperature particles produced by air gouging processes are common pollutants in cleaning workshops, which could endanger workers’ health. In this research, a two-way coupled Eulerian-Lagrangian method based on discrete phase modelling (DPM) was used to investigate the transport characteristics of high-temperature particles generated from air gouging processes. The particle group in the movement was divided into core zone and boundary zone, and the kinetic mechanism of particles in different zones was analysed. The results show particles in the boundary zone are more susceptible to the vortex entrainment effect than particles in the core zone, and some particles could be moved from the vortex diffusion zone to the vortex recirculation zone. The smaller the particle size, the better the followability to the hot airflow. The slower the temperature decay of particles, the more significant the thermophoresis effect, which could enhance the diffusion behaviour of the small particles. By analysing the average residence time of particles in the breathing zone, the influence of different factors on the average vertical diffusion height [Formula: see text] of particles is summarized, and a nonlinear regression prediction model of [Formula: see text] is established. The results can contribute to health risk assessment and industrial ventilation design.

Formulation and optimisation of Ozenoxacin topical nano-emulgel including a comprehensive methodology to qualify and validate the critical parameters of an in-vitro release test method and ex-vivo permeation test

Objective The purpose of this study was to formulate, optimize Ozenoxacin topical nano-emulsion using factorial design followed by to prepare and evaluate nano-emulgel using validated in-vitro release testing (IVRT) technique for determination of Ozenoxacin release rate along with ex-vivo permeation testing (EVPT). Significance: Nano-emulgel is a proven delivery system for poorly soluble substances works by enhancing the solubility and bioavailability. Factorial design provides a systematic and efficient means to study the effect of multiple factors on responses. IVRT is an USP compendia technique utilized for performance analysis of semi-solid formulations. Methods Nano-emulsion formulation optimization was done with factorial design, evaluated for globule size and % entrapment efficiency (EE). Nano-emulgels were characterized for assay, organic impurities, rheological behavior, IVRT, EVPT, and skin retention studies. IVRT validation was executed using vertical diffusion cells (VDCs). Results Ozenoxacin nano-emulsion was optimized with 1:1 ratio of Oil: Smix, 3:1 ratio of Surfactant:Co-Surfactant, and 15000 RPM of homogenization speed which resulted 414.6 ± 5.2 nm globule size and 92.8 ± 2.1% entrapment efficiency. Results confirmed that IVRT and Reversed Phase – High Performance Liquid Chromatographic techniques were validated as per regulatory guidelines. In-vitro, ex-vivo drug release, and skin retention from the optimized nano-emulgel formulation was comparatively higher (∼1.5 times) than that from the innovator (OZANEXTM) formulation. Conclusions Based on these results, Ozenoxacin nano-emulgel can be considered an effective alternative and was found to be stable at 40 °C/75% RH and 30 °C/75% RH storage condition for 6 months.

A holistic model for microplastic dispersion in a free-surface wetland flow

The holistic model for microplastic dispersion is essential to conserving natural wetlands and enhancing the sewage treatment efficiency of constructed wetlands. A holistic mode is presented to analyze the microplastic transport caused by a continuous point-source discharge of substances into a wetland with an exposed water surface. The microplastic cloud's total quantity and centroid movement over each streamline are rigorously derived using the method of separation of variables and integral transform, and its longitudinal dispersion, skewness, and kurtosis are numerically analyzed using the finite difference method. Three dimensionless groups for the microplastic movement in wetland are presented. The relative importance of autonomous movement to the vertical diffusion coefficient can noticeably influence the mass center velocity and the longitudinal spread of the microplastic cloud, and its augments can enhance the amplitude of skewness and kurtosis in the initial transport stage. For the transient stage of transport during which microplastic cloud develops, the pulsating term of emission intensity shows little effect on skewness and kurtosis. The oscillation of skewness and kurtosis show less obvious for the long term evolution of microplastic cloud when the time scale across the water depth by diffusion is much larger than the oscillatory period.

The fastest growing modes in rotating magnetoconvection with anisotropic diffusivities and their links to the Earth's core conditions

ABSTRACT The fastest growing modes in anisotropic rotating magnetoconvection (RMC) processes are presented. After reminding the state of the art, we present our new approach that applies to isotropic as well as anisotropic diffusivities' conditions. We describe three cases: T (only temperature perturbation is time dependent), Q (temperature and velocity field perturbations are time dependent, but magnetic field perturbation is time independent) and G (temperature, magnetic and velocity field perturbations are time dependent). Isotropies as well as anisotropies are further distinguished by values of molecular and turbulent diffusivities. We show that T case does not describe properly convection in the Earth's outer core conditions, because it implies too huge Ekman numbers for the transition between the RMC modes of weak and strong magnetic field types. In G case, the convection is usually much more facilitated than in the T case: instabilities may arise with much smaller values of Ekman number and, in general, all types of convections occur with values of the physical parameters of the Earth consistent with the most reliable estimations. We demonstrate (and indicate) that Q and G cases can be well suited for the magnetic field of the Earth (and for other planetary magnetic fields), but only G case may correspond to turbulent stay of the Earth's core. We prove that, analogously like in the marginal modes, the value of anisotropic parameter α (the ratio between horizontal and vertical diffusivities) crucially influences the convection. The cases of α < 1 ( 1 $ ]]> α > 1 ) strongly decrease (increase) the Ekman numbers at which the RMC modes of weak and strong magnetic field types change between each other. Finally, we show and stress that not all types of anisotropies in the fastest growing modes can be equally strong. More specifically, we show that a fixed Rayleigh number puts a constraint on the maximum value of α, but do not put any lower positive limit on the minimum value of α. This special constraint is given by the necessary positiveness of the growth rate of the fastest growing modes. Our RMC approach allows to easily deal with very huge wave numbers and Rayleigh numbers as well as with very small Ekman numbers, what is usually not possible in the standard geodynamo simulations.

Characterization of percutaneous absorption of calcium, magnesium, and potentially toxic elements in two tailored sulfurous therapeutic peloids: a comprehensive in vitro pilot study

Pelotherapy treatments in thermal spas, which utilize peloids composed of clay minerals mixed with saltwater or mineral-medicinal water, can have various effects on spa users, ranging from therapeutic to potential adverse reactions. Despite the widespread use of peloids, comprehensive information on the penetration and permeation of essential and potentially toxic elements into deeper layers of the skin during pelotherapy is limited. Understanding the concentrations of these elements is crucial for evaluating therapeutic benefits and ensuring safety. This study investigates the in vitro availability and absorption of calcium, magnesium, and potentially toxic elements in two peloids, considering their formulation matrix. To replicate the pelotherapy methodology, an in vitro permeation experiment was conducted using a vertical diffusion chamber (Franz cells) and a biological system with human skin membranes from five Caucasian women, age range between 25 and 51 years. The experiment involved heating the peloids to 45℃. The results emphasize the possible transport properties of chemical elements in peloids, providing valuable information related to potential therapeutic efficacy and safety considerations. Despite no apparent differences between peloids’ chemical composition, the method identified permeation variations among chemical elements. The methodology employed in this study adheres to the guidelines outlined by OECD for analyzing skin absorption through an in vitro approach. Furthermore, it aligns with the associated OECD guidance document for conducting skin absorption studies. The replicability of this methodology not only facilitates the analysis of peloids pre-formulation but also provides a robust means to evaluate the effectiveness of therapeutic elements during topical administration, particularly those with potential toxicity concerns.

First Determination in the Extended Corona of the 2D Thermal Evolution of a Current Sheet after a Solar Eruption

For the first time the evolution of the coronal reconfiguration after a coronal mass ejection (CME) was observed by the multichannel Metis Coronagraph on board the ESA–Solar Orbiter mission. The images acquired in visible light (VL) between 3.0 and 5.4 R ⊙ show the formation after a CME of a bright elongated radial feature interpreted as a post-CME current sheet (CS). The unique combination of VL and UV images allowed the time evolution of multiple plasma physical parameters inside and outside the CS region to be mapped in 2D for the first time. The CS electron temperature reached peak values higher than 1 MK, more than twice as high as the surrounding corona. An elongated vertical diffusion region, characterized as a region of much higher thermal pressure and lower magnetic pressure, is observed to slowly propagate outward during 13 hr of observations. Inside this region the Alfvénic Mach number is of the order of M A ≃ 0.02–0.11, the plasma β is close to unity, and the level of turbulence is higher than in the surrounding corona, but decreases slowly with time. All these results provide one of the most complete pictures of these features, and support the idea of a magnetic reconnection coupled with turbulence, thus allowing significant heating of the local plasma, despite the weakness of involved coronal magnetic fields in the considered altitude range.

Influence of Lee Wave Breaking on Far‐Field Mixing in the Deep Ocean

AbstractBreaking of internal lee waves generated by flow‐topography interaction is an important driving mechanism for abyssal mixing. By assuming that lee‐wave‐driven mixing is a local process, direct measurements in the past mainly focused on the water column over rough topography. In this study, a non‐local role of lee waves on remote mixing is investigated by using mooring observations in the northwestern Philippine Basin and a series of 2‐dimensional high‐resolution numerical simulations. We find that the breaking of lee waves can generate near‐inertial waves (NIWs) which can propagate away from their generation sites. The NIWs have strong vertical shear which can significantly elevate turbulent dissipation and mixing over remote uneven seafloor. Based on the topography perturbations numerical experiments, we find that for the remote gentle topography with inverse Froude number (Fr−1) between 0 and 0.5, the arrival of upstream NIWs can elevate the near‐bottom layer (0–1,000 m above bottom) dissipation rate and vertical diffusivity by 9.2 and 10.4 times, respectively at 30–50 km away from the NIWs source. For the remote rough topography with Fr−1 between 0 and 4, the corresponding increases are 3.5 and 4.4 times, respectively. The mechanism of upstream NIWs to elevate the downstream dissipation and mixing is through strengthening the shear instability over the far‐field topography, which is associated with NIWs' interactions with the topography and the generated lee waves therein. The results of this study will provide a foundation for improving the mixing parameterizations associated with current‐topography interactions.

Fire-Spread Characteristics and Evacuation Plan Optimization of Old Style Multi-Story Student Apartments

Fire is a major disaster event that can have a significant effect on public safety and social development. In a college or university, fire can seriously threaten the safety, lives, and property of those there due to the compact layout of apartment buildings and high population density. The ecological safety and sustainable development of buildings are also affected. In this study, PyroSim and Pathfinder software (version 2019) were used to simulate and analyze fire-spreading characteristics based on a multi-story university student apartment building. Additionally, the most effective safe evacuation plan from four fire evacuation drill schemes was identified by analyzing and comparing their performance. Results show that the spreading of fire smoke on different floors is significantly affected by the roof structure and the vertical and horizontal diffusion characteristics of smoke. While the smoke layer at the evacuation stairways has little effect on a safe evacuation, poor visibility due to smoke and ceiling temperatures has a significant effect. Safe evacuation becomes progressively more difficult at different floor levels from the top to the bottom of the building. The optimal safety scheme involves orderly evacuation through two open emergency exits. The number of emergency exits has a significant impact on the evacuation effectiveness. Measures and suggestions have been proposed to deal with apartment fires that address pre-event prevention, emergency loss reduction during the event, and post-event report-back. These proposals form an important theoretical reference for emergency evacuation and student apartment fire safety, providing important guidance for ecological safety protection of buildings and sustainable development.

Parameter estimation for ocean background vertical diffusivity coefficients in the Community Earth System Model (v1.2.1) and its impact on El Niño–Southern Oscillation forecasts

Abstract. This study investigates parameter estimation (PE) to enhance climate forecasts of a coupled general circulation model by adjusting the background vertical diffusivity coefficients in its ocean component. These parameters were initially identified through sensitivity experiments and subsequently estimated by assimilating the sea surface temperature and temperature–salinity profiles. This study expands the coupled data assimilation system of the Community Earth System Model (CESM) and the ensemble adjustment Kalman filter (EAKF) to enable parameter estimation. PE experiments were performed to establish balanced initial states and adjusted parameters for forecasting the El Niño–Southern Oscillation (ENSO). Comparing the model states between the PE experiment and a state estimation (SE) experiment revealed that PE can significantly reduce the uncertainty of these parameters and improve the quality of analysis. The forecasts obtained from PE and SE experiments further validate that PE has the potential to improve the forecast skill for ENSO.

Improvement of Stable Atmospheric Boundary Simulation with High-Spatiotemporal-Resolution Nudging over the North China Plain

The WRF model often struggles to accurately replicate specific characteristics of the atmospheric boundary layer, particularly under highly stable conditions. In this study, we reconstructed an OBS-nudging module using meteorological data with high spatiotemporal resolution, then coupled it in the WRF model (WRF-OBS) to improve stable boundary layer (SBL) simulation over the North China Plain (NCP). The results showed that WRF-OBS improved the simulation of SBL characteristics and reduced the deviation from observations significantly. The correlations (R2) between WRF-OBS simulations and observations of 2 m temperature, relative humidity, and 10 m wind speed at 460 stations across the NCP were 0.72, 0.56, and 0.75, respectively, which were much higher than the values for results from the unassimilated WRF model (WRF-BS). The simulated vertical profiles of temperature, relative humidity, and wind were generally consistent with observations at Pingyuan station. The meteorological factors which caused heavy air pollution was also investigated based on WRF-OBS simulation. The SBL characteristics obtained from WRF-OBS showed that light wind persisted over the NCP region during the period of heavy pollution, and Pingyuan was affected by warm and humid air. Vertically, the persistent temperature inversion at Pingyuan station was one of the main drivers of the heavy pollution. The WRF-OBS simulation captured the characteristics of the two temperature inversion layers very well. The two inversion layers covered the NCP, with a horizontal scale of approximately 200 km, and created very stable conditions, preventing the vertical diffusion of pollutants and maintaining high PM2.5 concentrations.

An Analytical Target Profile for the Development of an In Vitro Release Test Method and Apparatus Selection in the Case of Semisolid Topical Formulations.

This study focuses on how to define an Analytical Target Profile (ATP) which is intended for use in practice and on facilitating the selection of in vitro release test (IVRT) technology for diclofenac sodium topical hydrogel and cream. The implementation involves incorporating the new draft guidelines of the International Council for Harmonisation (ICH Q14) and USP (United States Pharmacopeia) Chapter 1220. Four IVRT apparatuses were compared (USP Apparatus II with immersion cell, USP Apparatus IV with semisolid adapter, static vertical diffusion cell, and a new, in-house-developed flow-through diffusion cell) with the help of the ATP. Performance characteristics such as accuracy, precision, cumulative amount released at the end of the IVRT experiment, and robustness were investigated. We found that the best apparatus for developing IVRT quality control (QC) tests in both cases was USP II with an immersion cell. All four different IVRT apparatuses were compared with each other and with the data found in the literature.

Vertical Distribution Mapping for Methane Fugitive Emissions Using Laser Path-Integral Sensing in Non-Cooperative Open Paths.

Observing the vertical diffusion distribution of methane fugitive emissions from oil/gas facilities is significant for predicting the pollutant's spatiotemporal transport and quantifying the random emission sources. A method is proposed for methane's vertical distribution mapping by combining the laser path-integral sensing in non-non-cooperative open paths and the computer-assisted tomography (CAT) techniques. It uses a vertical-plume-mapping optical path configuration and adapts the developed dynamic relaxation and simultaneous algebraic reconstruction technique (DR-SART) into methane-emission-distribution reconstruction. A self-made miniaturized TDLAS telemetry sensor provides a reliable path to integral concentration information in non-non-cooperative open paths, with Allan variance analysis yielding a 3.59 ppm·m sensitivity. We employed a six-indexes system for the reconstruction performance analysis of four potential optical path-projection configurations and conducted the corresponding validation experiment. The results have shown that that of multiple fan-beams combined with parallel-beam modes (MFPM) is better than the other optical path-projection configurations, and its reconstruction similarity coefficient (ε) is at least 22.4% higher. For the different methane gas bag-layout schemes, the reconstruction errors of maximum concentration (γm) are consistently around 0.05, with the positional errors of maximum concentration (δ) falling within the range of 0.01 to 0.025. Moreover, considering the trade-off between scanning duration and reconstruction accuracy, it is recommended to appropriately extend the sensor measurement time on a single optical path to mitigate the impact of mechanical vibrations induced by scanning motion.

Three dimensions advection-diffusion equation in unstable condition

The advection-Diffusion Equation in three dimensions was solved using the Separation variable, Substitution and Laplace transform methods, taking into account that eddy diffusivity along the horizontal, lateral coordinates and wind velocity are constant respectively, while the vertical eddy diffusivity is a function of the vertical height "z", Monin- Obukhov length "L" friction velocity at different emission rate and operation of iodine (I-131) in an unstable condition. We took the measured data from Inshas, Cairo, Egypt and compared the concentration of the calculated results with the results obtained from the solution equation at heights of 0.7, 27, and 43 meters. We found that all models are within a factor of two with the observed data from statistical evaluations in unstable conditions, we found that all models fell into a factor of two with the observed data. Whereas with NMSE and FB, the current models correlate better with the observed data.

Reverse‐phase high‐performance liquid chromatography methodology for film‐forming mafenide spray: Compatibility, assay, and in‐vitro release evaluation using Franz vertical diffusion cell apparatus

AbstractThis paper described a short and precise reverse‐phase high‐performance liquid chromatography (HPLC) method for quantifying mafenide in a film‐forming spray and preliminary in‐vitro release study. Following the International Council for Harmonization guidelines Q2 (R1), the method was validated. The chromatographic separation was achieved using a 10 mM potassium dihydrogen phosphate solution (mobile phase A) mixed with HPLC‐grade methanol (mobile phase B) in an 85:15 v/v ratio. Inert Sustain C8 (4.6 × 250 mm), 5 μm column was selected as the stationary phase. The flow rate was set as 0.8 mL/min, and detection was carried out at a wavelength of 222 nm. The developed HPLC method showed an accuracy between 98% and 102%. The primary diffusion study of film‐forming spray was performed using the Franz vertical diffusion cell apparatus. It was observed that an average of 26.94% of drug releases at 24 h. This indicates the drug has a slower release rate and shows local pharmacological action. The Weibull dissolution model was more fitting with regression square 0.9953. Furthermore, the drug excipient compatibility study revealed no interactions as the only drug peak was found in the chromatographic method, indicating that the chosen excipients were appropriate for a stable formulation.