Volume Of Buffer Research Articles

Tuning the Unloading and Infiltrating Behaviors of Li‐Ion by a Multiphases Gradient Interphase for High‐Rate Lithium Metal Anodes

AbstractThe random distribution of organic‐phases (OPs) and inorganic‐phases (IOPs) in native solid electrolyte interface (SEI) derived a sluggish Li‐ion de‐solvation and transmission, impairing the high‐rate performance of lithium metal anodes (LMAs). Herein, a multiphases gradient distribution hybrid interface is constructed on metallic Li by surface chemical reconstruction. Theoretical simulations and experiments verify that the Li‐ion unloading and infiltrating behaviors are tuned by functional complementary effects, enabling speedy kinetics. The upper OPs with polar functional group (─COO−) convert near‐surface solvation structure, pushing Li‐ion to unload the solvation cluster. Simultaneously, the bottom IOPs with plenty of crystal boundary accelerates Li‐ion infiltration. Moreover, flexible OPs cooperate with rigid IOPs to buffer volume fluctuation and suppress dendritic Li growth. Consequently, the lifespan of the composited electrode is significantly prolonged over 520 h at 5 mA cm−2. The full cells also exhibit an exhilarated rate performance and capacity retention even under a low N/P ratio (≈2.5). This work offers a characteristic insight for the rational design of gradient hybrid interface on the practical LMAs.

From Microsize Chromatographic Manufacturing for Fast Desalting to Its Characterization.

Microfluidic devices are becoming increasingly popular in protein analysis due to their ability to reduce sample and buffer volumes. However, there is a research gap concerning the coupling of this technology with ion mobility and mass spectrometry (IM-MS). This study aims to fill this void by introducing the manufacture and the characterization of a microsize exclusion chromatography (μSEC) module for fast desalting and its integration into microfluidics, along with its coupling to electrospray ionization and ion mobility mass spectrometry (ESI-IM-MS). To assess the feasibility of this approach, the desalting of α-synuclein (αS) was investigated using Bio Spin P6 gel as a stationary phase in the manufacture of a microfluidic device. αS detection by MS gives insight into the sample purity, while IM combined with MS provides information about protein structure. IM allowed both the recording of qualitative and quantitative information. The qualitative data provided a map of the conformers in equilibrium, while the calculation of the respective abundances (quantitative profile) of the conformers afforded the opportunity to describe the dynamics of the system. Our experiments, serving as proof-of-concept, demonstrate αS desalting, exchange buffer efficiency, and reduced solvent usage, without compromising the protein's structure.

Method Development and Validation for the Simultaneous Estimation of Lobeglitazone Sulphate and Glimepiride by HPLC Method.

A simple, precise, and accurate reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous estimation of lobeglitazone sulfate and glimepiride in bulk and tablet dosage forms. The method involved selecting various chromatographic parameters. Specifically, a new method was developed using a 250 mm × 4.6 mm (HSS) reverse-phase C18 column with 5 µm particle size (Shim-pack C18, 250 × 4.6 mm; 5 µm). The mobile phase consisted of 40 volumes of phosphate buffer (pH 3) and 60 volumes of acetonitrile, with methanol as the diluent, running as an isocratic elution. The flow rate was set at 1.0 mL/min, and UV detection was performed at 254 nm. The injection volume was 2 µL, and the total runtime was 10 minutes. The recoveries for lobeglitazone sulfate were found to be in the range of 101% to 100.6%, while those for glimepiride were in the range of 101.5% to 100%. The method’s accuracy is evident from these results. The inter-day and intra-day precision of the new method were both below the maximum allowable limit (RSD% ≤ 2.0), as per International Council on Harmonisation (Q2 R1) guidelines. The method exhibited a linear response, with correlation coefficient (r2) values of 0.9972% for pioglitazone and 0.998 for glimepiride. The validation parameters, such as accuracy, precision, linearity, specificity, stability in the analytical solution and robustness, met the acceptance criteria. Hence, this method can be effectively used for the simultaneous estimation of lobeglitazone sulfate and glimepiride in both bulk and pharmaceutical dosage forms.

Self-grown carbon nanotubes supported fluorine-free Mo2CTx conductive layers for efficient potassium storage

Mo2CTx is relatively less studied among MXenes family, especially for rechargeable alkali metal ion batteries. Herein, a systematic investigation has been conducted to unlock its potential as electrode materials in potassium-ion battery (PIBs), including innovative fluorine-free synthesis strategy, construction of heterostructure, and exploration of suitable electrolyte systems. Firstly, Cetyltriethylammnonium bromide (CTAB)-assisted etching route was provided to fabricate high-quality multilayer Mo2CTx with expanded interlayer space (C-Mo2CTx). The as-obtained C-Mo2CTx demonstrates a large specific capacity of 200 mAh g−1over 300 cycles in potassium-ion battery, surpassing the HF etched counterparts (F-Mo2CTx) by about 300 %. Afterwards, Zeolitic Imidazolate Frameworks (ZIF-67) derived Co, N-codoped carbon nanotubes (Co@NCNTs) were homogenously grown on the surface of Mo2CTx, working as embedding spacer to open the stacked Mo2CTx conductive layers (Mo2CTx-Co@NCNTs). Mo2CTx-Co@NCNTs electrode represents stable reversible capacity of 280 mA h g−1 over 300 cycles. The highly conductive matrix constructed by the strong bond between CNTs arrays and Mo2CTx conductive layer could provide numerous K-ion-diffusion pathways, and buffer volume strain and facilitate electron transfer. The present work proves the potential of Mo2CTx in PIBs and gives the systematic research methodologies on Mo2CTx-based materials in alkali metal ion storage.

Facile fabrication of graphene aerogel/Cu/CuO for enhanced sodium storage performance

It is widely recognized that CuO experiences volume expansion and conductivity issues, leading to unsatisfactory performance in sodium-ion batteries. A feasible approach to mitigate these challenges is the combination of Cu/CuO nanosheets with porous reduced graphene oxide aerogel (GA). In this study, an innovative composite of Cu/CuO nanosheets encapsulated within a 3D GA structure (GA/Cu/CuO) was synthesized via an alkaline exfoliation-mild self-assembly method. The results reveal that the Na+ storage properties of Cu/CuO/GA significantly surpassed those of pure CuO. Specifically, the GA/Cu/CuO exhibited a capacity retention of 320 mAh g–1 after 220 cycles at a current density of 0.1 A g–1, and demonstrated an optimized rate capability of 225 mAh g–1 at a current density of 1 A g–1. The enhanced rate and long-cycle performances are attributed to the synergistic effects of Cu/CuO nanosheets and porous GA, which shorten the Na+ transfer pathway, improve electronic/ionic conductivity, and buffer volume expansion during the discharge/charge process. Furthermore, the facile and innovative design strategy presented could be applicable to the synthesis of other composites for energy storage applications.

Using CFD to model the distortion of pollutant concentration signal at exhaust lines

The present study introduces a method for generating the distortion of species concentration signals within exhaust lines, employing Computational Fluid Dynamics (CFD) modelling instead of experimental techniques. Understanding distortion is important when e.g. tailpipe pollutant signals need to be correlated to engine operation patterns and related correction models need to be built. The approach was initially applied on a typical exhaust line geometry of a car, demonstrating the ability of CFD modelling to simulate the CO2 signal distortion from engine out to tailpipe, and was validated against laboratory measurements. Comparisons for variable operating points, between simulations and experiments, presented a good agreement with a deviation of up to 0.04 s in the time required for the signal to reach 50 % of its final output value (t50), and of up to 0.1 s in the rise time (t90-10). The methodology was applied to a vehicular exhaust line comprising tubing and buffer volumes, simulating catalysts or mufflers. This investigation aimed to identify the parameters that influence the distortion of CO2, revealing that inlet exhaust gas velocity can significantly impact CO2 distortion. Inlet temperature variations of ± 50 K produce a negligible deviation in t50 of ± 0.01 s for low inlet velocities and of ± 0.001 s for high inlet velocities. CFD is a useful tool to characterize pollutants signal generation within exhaust line configurations not limited to cars. Such a technique can be used to any mobile or stationary combustion system to study species concentration distortions caused by the individual components.

Full green assay of parenteral dosage forms of polymyxins utilizing xanthene dye: application to content uniformity testing

Due to the lack of other treatment options, a rebirth of polymyxins is urgently required. Colistin (also called polymyxin E) and polymyxin B are the only two examples of this antibiotic class that were effectively employed in such critical situations. In the present work, both of the two studied medications were quantified via a simple, green, and non-extracting spectrophotometric approach based on the formation of ion-pair complexes with Erythrosine B. Without using any organic solvents, the pink color of the created complexes was detected at wavelength = 558 nm. To achieve the highest intensity of absorbance, optimum conditions were established by the screening of many experimental factors such as pH, buffer volume, the volume of Erythrosine B, and the time consumed to undergo the reaction. For Colistin and Polymyxin B respectively, Beer-Lambert’s law was observed at the concentration ranges of 1–6, 1–9 µg mL− 1. The technique was approved and validated following ICH recommendations. Lastly, the suggested approach has been successfully implemented to quantify the cited medications colorimetrically, for the first time, in their parenteral dosage forms with excellent recoveries. Also, Content uniformity testing was implemented.

(Invited) From Solid-State Li-S to Polysulfide Flow Batteries: Challenges and Opportunities

Despite several decades of research and development work on Li-S batteries, there are still several fundamental issues that limits their performance and life. Controlling the polysulfide dissolution remains the major bottle neck in liquid electrolyte-based system. To alleviate this issue, there has been a steady progress in transitioning to quasi solid-state gel electrolytes and solid-state sulfur. The talk will cover some recent results on soft-chemistry approach by using a polymer gel electrolyte that has high ionic conductivity at RT and buffers volume changes during electrochemical activity. One example relates to fabrication a gel S-cathode on a carbon nanotube (CNT) matrix coated with a crosslinked network of polyethyleneimine -poly (ethylene oxide) (PEI-PEO), and solvated Li salt (LiTFSI). By optimizing the salt and polymer composition the conductivity of gel electrolyte exceeded 1x10-4 S/cm at RT. Design of high-performance solid-state sulfur cathode relies on effective ionic and electronic wiring with optimal composition of solid- electrolyte and electronic diluent such as carbon nanotube of highly graphitic carbon. Achieving high loading solid-state sulfur cathode is challenging due to limited ion-transport. The talk will cover recent work on catholyte design for sulfur cathodes using sulfide based solid electrolytes. In contrast, RT Li/Na polysulfide flow batteries provide a completely different geometry and architecture where the energy and power density is dictated by the solubility of the polysulfide species in the desired solvent and membrane design and stability. Acknowledgment This research is supported by Asst. Secretary, Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (VTO) through the Advanced Battery Materials Research (BMR) Program and Energy Storage Program, Office of Electricity, Department of Energy, USA.

Rigid-flexible mediated Co-polyimide enabling stable silicon anode in lithium-ion batteries

Silicon is considered as a promising electrode materials for the next generation of lithium-ion batteries. However, it’s commercial applications are hindered by significant volume changes. In this study, copolyimide binders with adjustable rigidity and flexibility were synthesized through simple copolymerization. The rigid segments containing adenine groups (p-APA) provide excellent mechanical strength and interface interaction, while flexible segments containing siloxane bonds and alkane chains (DS-NH2) can buffer volume changes through enhanced mobility and topological entanglement of molecular segments. Optimizing the copolymerization ratio helps minimize damage to the silicon electrode structure and stabilizes solid electrolyte interphase (SEI) growth. Compared to the rigid polyimide binders, rigid-flexible coupling strategy improves cycling stability, remaining a capacity of 2170 mAh/g at 2 A/g after 200 cycles and exhibiting stable cycling for over 750 cycles with a capacity limitation of 1500 mAh/g. The high mass loading silicon anodes, micron-sized silicon oxide electrodes and the full cells also exhibit favorable electrochemical performance. This research provides valuable insights for designing high-performance aromatic polymer binders for high energy density lithium-ion batteries.

Dual Strategy of Morphology Optimization and Interlayer Expansion in VS2 Cathode Toward High-Performance Mg-Li Hybrid Ion Batteries.

Combining the merits of the dendrite-free formation of a Mg anode and the fast kinetics of Li ions, the Mg-Li hybrid ion batteries (MLIBs) are considered an ideal energy storage system. However, the lack of advanced cathode materials limits their further practical application. Herein, we report a dual strategy of morphology optimization and interlayer expansion for the construction of hierarchical flower-like VS2 architecture coated by N-doped amorphous carbon layers. This tailored hierarchical flower-like structure coupled with homogeneous N-doped amorphous carbon layers cooperatively provide more active sites and buffer volume changes, thus realizing the enhancement of capacity and structural stability. Moreover, the enlarged interlayer spacing caused by the cointercalation of polyvinylpyrrolidone and ammonium ions can effectively promote the charge transfer rate and facilitate the rapid ion diffusion, as further demonstrated by electrochemical results and theoretical calculations. These features endow the hierarchical flower-like VS2 cathode with superior specific energy density (644.4 Wh kg-1, average voltage of 1.2 V vs Mg2+/Mg) and excellent rate capability (181.1 mAh g-1 at 2000 mA g-1). Systematic ex situ characterization measurements are employed to reveal the ion storage mechanism, which confirms that Li+ storage plays a leading role in the capacity contribution of MLIBs. Our strategy is in favor of providing useful insights to design and construct MLIBs with high energy density and excellent rate performance.

Influence of Polypyrrole on Phosphorus- and TiO2-Based Anode Nanomaterials for Li-Ion Batteries.

Phosphorus (P) and TiO2 have been extensively studied as anode materials for lithium-ion batteries (LIBs) due to their high specific capacities. However, P is limited by low electrical conductivity and significant volume changes during charge and discharge cycles, while TiO2 is hindered by low electrical conductivity and slow Li-ion diffusion. To address these issues, we synthesized organic-inorganic hybrid anode materials of P-polypyrrole (PPy) and TiO2-PPy, through in situ polymerization of pyrrole monomer in the presence of the nanoscale inorganic materials. These hybrid anode materials showed higher cycling stability and capacity compared to pure P and TiO2. The enhancements are attributed to the electrical conductivity and flexibility of PPy polymers, which improve the conductivity of the anode materials and effectively buffer volume changes to sustain structural integrity during the charge and discharge processes. Additionally, PPy can undergo polymerization to form multi-component composites for anode materials. In this study, we successfully synthesized a ternary composite anode material, P-TiO2-PPy, achieving a capacity of up to 1763 mAh/g over 1000 cycles.

Impact of Mild Gestational Diabetes Mellitus on Maternal and Fetal Liver Histopathological Alterations

Background: Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications that can affect the organ systems of the body in both the mother and fetus. This study aimed to determine the impact of mild GDM on maternal and fetal liver histopathological alterations. Materials and Methods: In this experimental study, 20 pregnant Wistar rats were randomly allocated in control and diabetic groups. Mild hyperglycemia was induced by intraperitoneal injection of streptozotocin (40 mg/kg body weight) on the 5th day of gestation. The control group received an equal volume of citrate buffer. The diabetic state was confirmed by a blood glucose level of 120–300 mg/dL. Maternal and fetal liver samples were obtained on day 19 of gestation and stained with hematoxylin and eosin for histopathological investigation. Results: Liver sections of diabetic dams exhibited edematous hepatocytes and scattered pyknotic and necrotic cells with dilated sinusoids and congested central veins. The portal tracts showed the proliferation of bile ducts with mild chronic inflammatory cells infiltrating together with fibrosis beyond the limited plate which extends to the central vein (porto-central fibrosis). Liver sections of their fetuses revealed edematous hepatocytes with increased necrotic cells, with pyknotic nuclei, dilatation of the hepatic sinusoids, and their central veins. There was also a relative increase in megakaryocytes, which promoted fibrosis and distorted vascular beds of the hepatic tissue. The portal tracts also showed bile duct proliferation. Conclusion: This study highlighted the adverse effects of uncontrolled mild GDM on liver structure in rat dams and their fetuses.

Flooding Resiliency of Surigao del Sur, Caraga Region, Philippines Residences Through Rainwater Catchment and Storage System

Urbanised areas in Northeastern Mindanao have a problem of addressing flooding occurrences. This study primarily aimed to provide insights into how the rainwater catchment system of uptown communities and their cooperation could increase flood resiliency of downtown communities in the Surigao del Sur, Caraga Region, Philippines. This research employed quantitative analysis of the eleven (11) year (2010-2020) data from the Philippine Atmospheric, Geophysical, and Astronomical Services Administration - Hinatuan, Surigao del Sur station. The recommendable optimum rainwater storage capacities for a given number of household occupants, roof areas at run-off efficiency of 90%, and three (3) day rainfall characteristics at 36.9% averaged probability of exceedance were initially determined. Through scenario analysis, uptown communities emptying their rainwater storages before heavy downpour occurs could provide sufficient flood volume reduction and buffer time for downtown communities to prepare. The output of this research is vital in the environmental planning, management, and policies of cities and regions.

Success Of Cartilage Grafting with Mastoidectomy In Revision Tympanoplasty

Aims and Objectives: Candidates having non-cholesteatomatous chronic otitis media who have failed tympanoplasty in first attempt (graft used conchal or tragal cartilage) is at higher risk of failure in subsequent repair. The adjunctive use of mastoidectomy with cartilage tympanoplasty (tragal or conchal) in these patients has decreased the risk for subsequent failure. Aim of our study is to compare effect of mastoidectomy in revision cartilage tympanoplasty in terms of successful graft uptake, hearing improvement, and prevalence of other complications. The arguments in favor of mastoidectomy include the facts that the open mastoid cavity provides an improved volume and pressure buffer, rids the mastoid of diseased mucosa, and ensures adequate patency of the aditus (14– 16). Although this logic is sound and is supported in the literature, we believe that in many revision cases, reconstruction with a robust material such as cartilage provides the additional stability necessary to allow the middle ear and mastoid to revert naturally to a normalized environment.

Cycling performance of SiOx-Si-C composite anode with different blend ratios of PAA-CMC as binder for lithium sulfur batteries

Silicon (Si) -based materials have been identified as a potential alternative anode owing to their superior theoretical capacity compared to conventional graphitic carbon. Nevertheless, the huge volume change (approximately 300%) that occurs while cycling still hampers this system from 100% practical applications. Silicon-monoxide (SiOx)-based anode materials, on the other hand, are being explored extensively due to their unique properties such as high theoretical capacity, formation of Li2O and LiSiO4 during initial lithiation process that act as a natural volume buffer matrix to accommodate volume changes and formation of a stable solid electrolyte interphase layer, which improves the cyclability and capacity retention. Although poly (vinylidene fluoride) (PVdF) is widely used as a binder, the weak van der Waals forces between PVdF and silicon-based particles fail to bind particles effectively, when substantial volume change occurs. Herein, we prepare a series of SiOx-Si-C electrodes with different binders poly (acrylic acid) (PAA), carboxyl methyl cellulose (CMC) and their blends as binder. The prepared polymeric blends are subjected to thermal, morphological, mechanical and physico-chemical analyses. The Li/ SiOx-Si-C cell assembled with 100% PAA as binder delivered a discharge capacity of 1908 mAh g−1 on its first cycle and 724 mAh g−1 on its 100th cycle with a fade in capacity of 11.8 mAh g−1 per cycle. Upon the incorporation of CMC in the PAA blend the cycling performance was found to be poor. Among the various investigated compositions, the electrode with sole poly (acrylic acid) as a binder offers the highest discharge capacity and this is attributed to the high concentration of the functional (carboxylic) group which forms strong hydrogen bonds with - OH groups on the SiOx or carbon surface. The interfacial properties of the polymeric binders are thoroughly investigated by spectroscopies and electrochemical tests.Graphical abstract

Amorphous and crystalline Sb2S3 nanoparticles embedded in N/S co-doped carbon as anodes for potassium-ion batteries

Antimony trisulfide (Sb2S3) has emerged as a promising anode candidate for potassium-ion batteries (PIBs) owing to its low cost and high theoretical specific capacity. However, its large volume expansion upon K+ storage and sluggish kinetics result in poor cycling performance and rate capability. To address these challenges, rational structural design is highly desirable. Herein, we report the synthesis of amorphous and crystalline Sb2S3 nanoparticles embedded in N/S co-doped carbon composites (a-Sb2S3@NSC and c-Sb2S3@NSC) via a facile organic coating combined with subsequent carbonization and sulfidation processes. When used as a PIBs anode material, a-Sb2S3@NSC exhibits a high discharge specific capacity of 415.6 mAh g−1 after 50 cycles at 200 mA g−1 and a stable rate capability (224.8 mAh g−1 at 2 A g−1), which remarkably outperforms that of the c-Sb2S3@NSC with inferior specific capacity (311.5 mAh g−1) and poor rate capability (67.7 mAh g−1). The amorphous structure of Sb2S3 nanoparticles in a-Sb2S3@NSC provides abundant defects and structural disorder, which reduces the entropy energy and activation barrier associated with K+ incorporation, effectively facilitating the transport and storage of K+. Moreover, the synergistic interactions between amorphous Sb2S3 nanoparticles and N/S co-doped carbon can effectively improve the electron/ion reaction kinetics and buffer volume variations, thus leading to superior potassium storage performances.

Miniaturization study on helmholtz-based photoacoustic cell for PAS-based trace gas detection

In this study, the acoustic behavior and gas flow noise in a Helmholtz photoacoustic cell were simulated and optimized to study the influence of the cell dimensions and buffer structure. Numerical analysis using finite element analysis and experimental validation were performed in this study. A spindle-type photoacoustic cell with a resonator volume of 0.5 mL and buffer volume of 0.4 mL was selected for CH4 detection. Besides its strong photoacoustic enhancement, the spindle-type buffer structure has the best ability to eliminate flow noise compared to the other buffer structures. A linearity of 0.9992 was achieved over a wide concentration range of 0–10000 ppm in the CH4 measurement experiment. The 1σ equivalent detection limit for a response time of 10 s was measured to be 0.49 ppm. Allan deviation analysis indicated that a minimum detection limit of 17.9 ppb can be achieved by extending the integration time to 4760 s.

Multiscale structural engineering of Co0.85Se@porous carbon composite enables highly reversible lithium/sodium storage

Cobalt selenide (Co0.85Se) has been regarded as the most potential anode material for both lithium/sodium ion batteries (LIBs and SIBs) due to its high specific capacity and excellent pseudocapacitive effect. However, the inevitable volume expansion during conversion reaction and grievous dissolution of Se in electrolytes seriously undermine its reversibility and cycling stability. Combining the transition-metal chalcogenides with stable porous carbon networks is considered as one of the most effective strategies to improve electrochemical stability and conductivity of transition-metal chalcogenides. Here, we proposed a multiscale structural engineering strategy to encapsulate selenide nanoparticles in N-doped porous carbon to enable high-performance Co0.85Se@porous carbon composite for highly reversible lithium/sodium storage. Specifically, the Co0.85Se nanoparticles are tightly anchored to carbon network through substantial SeC bond, which effectively buffer volume expansion and inhibit the dissolution of Se in electrolytes. Additionally, the carbon pores with multilevel size help achieving the fast ions diffusion. The unique structure enables the Co0.85Se composite anode to exhibit excellent discharge capacities of 955.1 mAh g−1 at 100 mA g−1 after 100 cycles, 305.6 mAh g−1 at 1 A g−1 of full cells after 550 cycles in LIBs and 491.3 mAh g−1 at 100 mA g−1 after 100 cycles in SIBs.

Boron-manganese-nitrogen co-doped three-dimensional porous carbon realizes superior capacitive lithium-ion storage

Three-dimensional (3D) porous carbon has sufficient specific surface area and anchor positioning points. The pore structure facilitates uniform charge distribution, and buffers volume changes during stripping. However, single carbon materials have limited theoretical capacity and short cycle life. Here, 3D porous carbon material BCN/Mn-6 (B,N and Mn co-doped porous carbon with 6 mmol Mn content) co-doped with manganese, boron and nitrogen was synthesized by heat treatment. Affective modulation of the material structure and surface functional groups was achieved by adjusting the amount of manganese doping. The metal element doping can promote the diffusion of lithium ions, and the formed vacancies and defects can be used as lithium storage sites. Nitrogen doping can improve the dispersion and stability of metals and oxides, and regulate the redox capacity. Co-doping of metals and heteroatoms synergistically improves electrical conductivity. Thus, BCN/Mn-6 exhibits excellent cycling stability (99.60 % Coulombic efficiency after 300 cycles) and specific capacity (779.9 mAh/g), and shows capacity rise. This study provides a new direction for the preparation of carbon-based electrode materials doped with heteroatoms and the study of capacitive energy storage mechanisms.

OPTIMIZATION OF DRIED BLOOD SPOT ASSAYS FOR HEPATITIS B VIRUS SURFACE ANTIBODY QUANTIFICATION.

Dried blood spot (DBS) cards can be used as an alternative sample collection method to plasma, however, there is no optimized elution protocol for DBS cards specifically for hepatitis B surface antibody (anti-HBs) testing. The study aimed to develop a DBS elution protocol for anti-HBs quantification. Our study sought to determine the ideal phosphate-buffered saline (PBS) buffer volume to use by comparing three PBS volumes (300uL, 450uL, and 500uL), and the optimal time to agitate DBS discs on a plate shaker (1hr, 2hrs, 3hrs, and 4hrs) to yield DBS anti-HBs concentrations that are comparable to corresponding plasma anti-HBs concentrations. The optimal DBS storage temperature (25°C, -20°C, and -80°C) was investigated to determine the ideal long-term storage temperature of the cards. Residual samples were used for optimization (2019-2021). A total of 50 DBS-plasma pairs was used throughout the study, with plasma anti-HBs concentrations being used as the golden standard to compare. The analysis of results was carried out by determining the p-values of the Wilcoxon sign rank. A two-way analysis of variance (ANOVA) was also performed to determine the impact of PBS elution volumes, elution time, and storage temperature on the anti-HBs concentration of DBS samples on STATA Version 15.0. No statistically significant difference between the DBS-plasma anti-HBs pairs was observed when using 450 or 500uL of PBS buffer and when samples were agitated for 3 hours (p=0.594, p=0.499 respectively). The optimal storage temperature for DBS cards was 25°C because the results showed no statistically significant difference between DBS-plasma anti-HBs titers (p=0.594). The two-way ANOVA analysis showed that elution volumes and time had no statistically significant impact on the DBS anti-HBs concentrations, p=0.948 and p=0.381 respectively. Storage temperature had a statistically significant impact on the DBS anti-HBs concentrations, p=0.002. The optimized DBS elution protocol for anti-HBs quantification will help monitor vaccine efficacy in infants due to the low sample volumes required compared to plasma and also can be used for anti-HBs testing in resource-limited areas around the country.