Effect Of Various pH Research Articles

A highly sensitive and green electroanalytical method for the determination of favipiravir in pharmaceutical and biological fluids

BackgroundFavipiravir is currently used for the treatment of coronavirus disease-2019 (COVID-19).ObjectiveA highly sensitive and eco-friendly electroanalytical method was developed to quantify favipiravir.MethodThe voltammetric method optimized a sensor composed of reduced graphene oxide / modified carbon paste electrode in the presence of an anionic surfactant, improving the favipiravir detection limit. The investigation reveals that favipiravir-oxidation is a diffusion-controlled irreversible process. The effects of various pH and scan rates on oxidation anodic peak current were investigated.ResultsThe developed method offers a wide linear dynamic range of 1.5–420 ng/mL alongside a higher sensitivity with a limit of detection in the nanogram range (0.44 ng/mL) and a limit of quantification in the low nanogram range (1.34 ng/mL).ConclusionThe proposed method was applied for the determination of favipiravir in the dosage form, human plasma and urine samples. The developed method exhibited good selectivity in the presence of two potential electroactive biological interferants, uric acid which increases during favipiravir therapy and the recommended co-administered vitamin C. The organic solvent-free method greenness was evaluated via the Green Analytical Procedure Index, The present work offers a simple, sensitive and environment-friendly method fulfilling green chemistry concepts.

Characterization and Adsorption Capacity of Modified Biochar for Sulfamethylimidine and Methylene Blue in Water.

In this study, a composite of pond mud and lanthanum- and nano-zero valent iron-modified-biochar was investigated for its ability to adsorb methylene blue (MB) and sulfamethazine (SMZ). La-modified attapulgite and nano-zero valent iron (surface area enhanced by 43.7% via Brunauer-Emmett-Teller analysis) were successfully loaded onto the straw-sediment biochar (BC) surface. With the increase in pyrolysis temperature, the biocompatibility yield, the H, O, and N content, and the ratio of carbon elements decreased, while the pH value, surficial micropores, C element, and ash content increased. The biocarbon small molecules were gradually and tightly ordered, and the organic groups such as hydroxyl, carboxyl groups, and carbon oxygen double bonds were gradually lost or disappeared. The original Fe-BC had more phenolic hydroxyl groups forming an intermolecular hydrogen bond than others with a higher adsorption capacity possibly through the Schiff base reaction. The effect of various pH (2-9), temperature (15-35 °C), and initial concentration (1-25 mg L-1) on adsorption was investigated. pH and temperature were the main factors governing the adsorption process. The maximum adsorption capacity was observed at pH 4. The adsorption performances for MB followed the order Fe-BC > La-BC > BC, and the maximum removal rate was over 98.45% with pH = 7. The three types of BC dosages between 0.2 (6.67 g L-1) and 0.4 g showed a removal rate of 99% for MB. The adsorption capacity of Fe-BC, La-BC, and BC for MB was 2.201, 1.905, and 2.401 mg L-1 with pH = 4, while 4.79, 4.58, and 5.55 mg g-1 were observed with BC dosage at 0.025 g. For SMZ, the higher the temperature, the better the adsorption effect, and it reaches saturation at approximately 25 °C. To further evaluate the nature of adsorption, Langmuir/Freundlich/Temkin models were tested and the adsorption capacities were evaluated on the surface of the BC composite. The three modified materials were physisorbed to SMZ, while MB was chemisorbed. For MB, the adsorption performance of BC is the best < 0.2 g (6.67 g L-1) at pH 7.0 at 35 °C. The Elovich model was more suitable for MB, while the Freundlich and Temkin models could better fit the adsorption process of MB. The preparatory secondary dynamics equation and Langmuir equation were more compliant for SMZ, and the saturated adsorption capacities of straw-modified, La-BC, and Fe-BC reached 5.699, 6.088, and 5.678 mg L-1, respectively.

Extraction and Characterization of Type I Collagen from Parrotfish (Scarus sordidus Forsskål, 1775) Scale solubilized with the Aid of Acetic Acid and Pepsin.

Waste from marine fish processing is an important source of valuable products. Fish collagen is considered a alternative biomaterial due to its excellent properties, and it is widely used for industrial purposes. Thus, this present study aimed to characterize acid and pepsin-soluble collagens from the waste of parrotfish (Scarus sordidus Forsskål, 1775) scales. The yields (p > 0.05) of acid-soluble collagen (ASC-PFS) and pepsin-soluble collagen (PSC-PFS) were 1.17 g/100 g and 1.00 g/100 g, respectively. Both collagen samples were categorized as type I owing to the presence of two alpha chain subunits (α1 and α1) after being confirmed by a sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Under the fourier transform infrared (FTIR) test, the triple helical structure of type I collagens from the ASC-PFS and PSC-PFS was maintained. Moreover, the study of UV visible spectra and X-ray diffraction (XRD) showed the similarity of collagens derived from different fish species, and the thermostability (T max) evaluation of all extracted collagens was in the range of 36.22-37.78°C, and their values were comparable to previous research on the fish scale collagens. The effect of various pH and sodium chloride (NaCl) treatments on solubility exhibited that the ASC-PFS and PSC-PFS were highly soluble in an acidic condition (pH < 5.0) and low concentration of sodium chloride (<30 g/L). Taken together, collagens extracted from parrotfish scale waste can be an alternative source for industries.

Z-scheme CuO/Fe3O4/GO heterojunction photocatalyst: Enhanced photocatalytic performance for elimination of tetracycline

CuO/Fe3O4/GO, as a Z-scheme heterojunction catalyst, was successfully synthesized and used as a photocatalyst for removing tetracycline from aqueous solution. The CuO/Fe3O4/GO heterogeneous catalyst combines the narrow bandgap semiconductor CuO, oxygen vacancies of Fe3O4, and oxygen-containing reaction sites of GO. Without the addition of activators (persulfate or H2O2), the photocatalytic performance on decomposing tetracycline is very excellent. Compared with GO, Fe3O4, and CuO, CuO/Fe3O4/GO exhibits superior photocatalytic performance. Under visible light radiation, CuO/Fe3O4/GO generates h+ and ⋅O2−, which are the mainly responsible active groups for TC degradation. The effects of various pH, catalysts, and reuse on the degradation performance are evaluated, and the optimal conditions for CuO/Fe3O4/GO removal of tetracycline are obtained at pH 7, catalyst dosage 20 mg⋅L−1, TC at a concentration of 30 mg/L, nearly 97.3% of tetracycline is decomposed. This study has great potential in the treatment of wastewater containing various antibiotics.

VARIASI PH PADA MEDIA TUMBUH DAN SUHU FERMENTASI DALAM MEMPRODUKSI ETANOL OLEH ISOLAT BU3.111E1

The aim of this research was to determine the growth phase curve of BU3.111E1 and to determine the effect of various pH and temperatures on BU3.111E1 isolate growth media to produce ethanol. These experiment was carried out in stages, namely culture stock rejuvenation, culture grow and adjustment, measuring the effects of various pH and temperature in media upon fermentation followed by distillation. This study used two variations of pH (4.0 and 5.0) and three variations of temperature (18, 24 and 30°C) and two repetitions. The growth curve of BU3.111E1 isolate showed that the isolate grew in 33 hours, starting from the exponential phase, stationary phase to the death phase. The fermentation results showed that, pH 4.0 at 30°C produced the highest ethanol which was 15.05 mL with a total dissolved solids of 2.50 (?% brix). pH 5.0 at 18°C ??was produced the lowest ethanol, which was 3.47 mL with a total dissolved solids of 0.65 (?% brix). The results indicate that pH and temperature affect bacteria during fermentation to produce ethanol.

A preliminary assessment of pregabalin lactam mutagenicity and remarks on “An investigation of pregabalin lactamization process and effect of various pH on reaction: A computational insight”

A computational investigation into pregabalin lactamization has been recently published, confirming that the reaction depends on pH and allowing a reasonable pathway for the formation of the impurity pregabalin lactam (prega-L) to be proposed. However, without proof or regulatory criteria, that investigation assumed that the impurity pregabalin lactam (prega-L) has high toxicity potential, which is worrisome. The present communication reports on the preliminary assessment of the prega-L toxicity by computational methods. The principles outlined in the ICH guidance M7 are followed, and statistics- and rule-based methodologies (in silico models) are used; the mutagenicity potential is considered as endpoint, and implications for qualifying this impurity in drug substances and/or drug products are discussed.

Computational studies on binding, solvent, and pH effects on (S)-propranolol and methacrylic acid complex

Density functional theory methods have been applied to understand binding of (s)-propranolol, a template, to a methacrylic acid molecule acting as a functional monomer using basic 1:1 model. The model has been expanded to study the effect of various pH by adding hydronium and hydroxide ions solvated by water molecules to the template-monomer system, to mimic acidic and basic environments, respectively. This could be considered a model study towards a potential use of molecular imprinting method for the design of a transdermal patch for a topical and direct delivery of (s)-propranolol to hemangiomas. In addition, this study provides detailed binding site analysis of the template and functional monomer verified by the theoretical IR spectra analysis, as well as solvent and pH effects on template-monomer binding energy.

AKTIVITAS ANTIOKSIDAN EKSTRAK BUAH PARIJOTO PADA BERBAGAI PH PENGOLAHAN PANGAN

Food processing can be done in the pH range from acid to base. This research aims to study the effect of various pH of food processing on antioxidant activity and total phenol extract of Parijoto fruit. Testing was carried out at pH 2, 4, 7, 8, and 10. Analysis of antioxidant activity using the DPPH radical scavenging activity method. Whereas phenol analysis uses the Folin Ciocalteu method. The results showed that the pH difference significantly affected the antioxidant activity and the total phenol extract of Parijoto fruit. Increasing pH causes an increase in antioxidant activity and in line with an increase in total phenol. Application of processing products from parijoto at higher pH will produce antioxidant activity and total phenols which tend to be higher.

An investigation of pregabalin lactamization process and effect of various pH on reaction: A computational insight

The present work aims to provide a comprehensive insight into the lactamization reaction of pregabalin. Pregabalin which is an anticonvulsant drug can be degraded directly. This degradation reaction results in the generation of pregabalin lactam (prega-L) which is a highly toxic form. In this study, the geometry, energy landscape, kinetic and thermodynamic preference of this reaction were analyzed and investigated. The molecular dynamic (MD) simulations, density functional theory and the CBS-4M levels of theory were employed in order to carry out all the calculations. The lactamization reaction can be categorized as an intramolecular cyclization which after dehydration leads to the generation of pregabalin-lactam. The initial stage in this degradation reaction is the transformation of stable isomers into the unstable form, R∗. According to the calculations, there is a transition state close to the R∗. This transition state possesses 25.96 kcal/mol more energy than the ground state, R∗ (0.82 kcal/mol). Results of intrinsic reaction coordinates (IRC) calculations confirmed that this transition state ends up to pregabalin-lactam in one direction while it leads to the unstable R∗ in the other. Moreover, the values of energy were studied for both protonation and deprotonation forms of pregabalin to elucidate the role of different pH (acidic/basic) on this reaction. The obtained results confirmed that lactamization reaction depends on pH.

Study on the effect of solution conditions on heat induced-aggregation of human alpha interferon.

A major problem in the formulation of therapeutic proteins is the irreversible protein aggregation. Recombinant human interferon alpha2b (rhIFNα2b) has poor stability and undergoes physical degradation. The aim of this study was to investigate the effect of solution conditions on the heat-induced aggregation of rhIFNα2b. The protein was incubated for 1 h at 40-70 °C and for up to 240 h at 50 °C and its aggregation tendency was then studied using optical density (at 350 nm), SE-HPLC, dynamic light scattering and SDS-PAGE methods. The effect of various pH (5, 6 and 7) and buffer concentrations (10, 55 and 100 mM) on the aggregation of protein following incubation at 50 °C for 72 h was also evaluated. The results obtained for samples incubated at 50 °C for up to 240 h showed that OD350 and the amount of higher molecular weight aggregates (HMW) increased and the monomer content decreased significantly (p<0.05) as the incubation time increased. Following incubation at various temperatures, a significant increase in OD350, drop in monomer content and increase in the amount of HMW aggregates were observed (p<0.05). Data obtained from incubation of samples at 50 °C for 72 h confirmed that regardless of the buffer concentration, the percentage of monomer at pH 6 was significantly higher than that at pH 7 and pH 5 (p<0.05). At constant pH, although not significant, the same trend was observed when the buffer concentration increased to 100 mM. In conclusion, the change in solution conditions can influence the aggregation extent of rhIFNα2b.

The synthesis and spectroscopic characterization of nano calcium fluorapatite using tetra-butylammonium fluoride

Pure homogeneous nano sized biocompatible fluorapatite (FAp) particles were synthesized by a wet chemical procedure using water soluble tetra-butylammonium fluoride (TBAF) without using high temperatures and any purification processes. Combination of the Bragg's law and the plane-spacing equation for the two high intensity lines, namely, (0 0 2) and (3 0 0), gives a = 9.3531 Å, c = 6.8841 Å, confirms the identity of the highly crystalline synthetic material as well as its purity. The effect of various pH's in crystal formation and on their size was also evaluated. The calculated crystallinities were excellent with a rate around 5.0. The synthesized nano FAp was fully characterized by spectroscopic techniques (XRD, SEM, EDS, BET, FT-IR and ICP-AES). The nitrogen adsorption–desorption isotherm showed a type IV diagram and calculation of the surface area was investigated as well.

Silver sol immunoagglutination assay for determination of human IgG

Immunoagglutination properties of silver nanoparticles sensitized with antibodies to human IgG for determination of IgG were studied. Effects of various pH on sensitization and consequent immunoagglutination process were investigated. It was shown that the best results were obtained when sensitization and immunoagglutination were conducted at isoelectric point of IgG molecule. It was demonstrated that immunoassay with colloidal silver nanoparticles provides the detection of antigen in wide range of concentrations.

Self-Oscillatory Actuation at Constant DC Voltage with pH-Sensitive Chitosan/Polyaniline Hydrogel Blend

Hydrogels constructed from semi-interpenetrating polymer networks (semi-IPNs) of chitosan and polyaniline (CP) were prepared and the effect of various pH (1, 4, 7, 10) levels on the equilibrium water content (EWC) and electromechanical response were investigated. In swelling experiments, the freeze-dried membranes exhibited a high EWC value in acidic conditions. The electromechanical behavior of the CP membranes was also measured in a direct current electric field in pH buffer solutions. The electric potential induced bending actuation in the membrane, with the direction of bending being reversed in acidic and basic solutions. A novel oscillatory bending was observed in neutral electrolyte, which may ultimately prove useful as a simple propulsion mechanism in fishlike swimming robots or for simple pumps.

Synthesis and characteristics of semi‐interpenetrating polymer network hydrogels based on chitosan and poly(hydroxy ethyl methacrylate)

AbstractSemi‐interpenetrating polymer networks (semi‐IPNs), composed of chitosan and poly(hydroxy ethyl methacrylate) hydrogels, were prepared and the effects of various pH, temperatures, and an electric‐field on the swollen hydrogels were investigated. The swelling kinetics increased rapidly, reaching equilibrium within 60 min. Semi‐IPN hydrogels exhibited relatively high swelling ratios, 150∼350%. The swelling ratio increased when the pH of the buffer was below pH 7 as a result of the dissociation of ionic bonds. Semi‐IPN hydrogels showed electroresponsiveness by shrinking when an electric field was applied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 86–92, 2005

Stability studies of propoxur herbicide in environmental water samples by liquid chromatography–atmospheric pressure chemical ionization ion-trap mass spectrometry

Liquid chromatography–atmospheric pressure ionization ion-trap mass spectrometry has been investigated for the analysis of polar pesticides in water. The degradation behavior of propoxur, selected as a model pesticide belonging to the N-methylcarbamate group, in various aqueous matrices (Milli-Q water, drinking water, rain water, seawater and river water) was investigated. Two interfaces of atmospheric pressure ionization, atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), were compared during the study. Propoxur and its transformation product ( N-methylformamide) were best ionized as positive ions with both APCI and ESI, while another transformation product (2-isopropoxyphenol) yielded stronger signals as negative ions only with APCI. In addition, the effects of various pH, matrix type and irradiation sources (sunlight, darkness, indoor lighting and artificial UV lamp) on the chemical degradation (hydrolysis) were also assessed. From the kinetic studies of degradation, it was found that the half-life of propoxur was reduced from 327 to 161 h in Milli-Q water with variation of irradiation conditions from dark to sunlight exposure. Degradation rates largely increased with increasing pH. The half-life of the target compound dissolved in Milli-Q water under darkness decreased from 407 to 3 h when the pH of Milli-Q water was increased from 5 to 8.5. These suggest that hydrolysis of propoxur is light-intensity and pH-dependent. In order to mimic contaminated natural environmental waters, propoxur was spiked into real water samples at 30 μg/l. The degradation of propoxur in such water samples under various conditions were studied in detail and compared. With the ion trap run in a time-scheduled single ion monitoring mode, typical limits of detection of the instrument were in the range of 1–10 μg/l.

Effect of pH and glucose on cultured human peritoneal mesothelial cells.

We investigated the effects of various pH and glucose concentrations on the growth of human peritoneal mesothelial cells and on coagulation and fibrinolytic factors. Cells were cultured at various pH values in Ham's F-12 medium containing 1.0% foetal calf serum and supplemented with D-glucose or D-mannitol at various concentrations. After 4-48 h, cell proliferation and 3H-thymidine incorporation were determined. Coagulation and fibrinolytic factors were measured after 48 h. Glucose caused concentration-dependent inhibition of cell growth at all pH values, but the deleterious effect of low pH on cell proliferation was faster and stronger than that of high glucose. At a similar osmolality, mannitol caused less inhibition of cell proliferation than glucose. There was a glucose concentration-dependent increase of thrombin-antithrombin III complex production at all pH values. At pH 5.2, tissue-type plasminogen activator production was far lower than at higher pH values, and production of the plasminogen activator inhibitor showed a glucose concentration-dependent increase. At pH 6.5 or 7.3, however, the plasminogen activator inhibitor production decreased and tissue-type plasminogen activator production increased in a glucose concentration-dependent manner. Low pH and/or high glucose culture medium had an inhibitory effect on peritoneal mesothelial cells, with the effect of high glucose being partially related to hyperosmolality. These cells may modulate peritoneal coagulant and fibrinolytic activity, with the balance between coagulation and fibrinolysis being disturbed by low pH and/or high glucose.

Chemical aging effects on the physio-mechanical properties of polyester and polypropylene geotextiles

The influence of groundwater chemistry on the durability of geotextiles is important for the design of municipal and hazardous waste landfills, geotextile reinforcement of slopes and subgrades, and earth retention systems. A series of tests are described in this paper, which explore the effects of various pH and saline environments on geotextiles, thus contributing to an improved understanding of durability as a basis for design. Accelerated aging was performed on polyester and polypropylane geotextiles at room temperature and temperatures elevated to 95°C for six months in saline ( ph∼8 ), strong alkaline (pH 10) and acidic (pH 3) media. Property changes as a result of aging were studied using tensile testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and intrinsic-viscosity (I.V.) measurements. Scanning electron microscopy (SEM) was employed to study changes in the surface topography of the fibers upon aging. An Arrhenius model was used to extrapolate results of this short term study to the actual lifetime of the geotextiles. Results indicate that polyester undergoes hydrolytic degradation under both acidic and alkaline conditions at and above the glass transition temperature, with the degradation being more severe under alkaline conditions. The polypropylene geotextile, on the other hand, was relatively inert to the pH conditions and showed no changes in strength. An increase in crystallinity in the initial period of aging was observed for both polyester and polypropylene. In polyester, this was due to preferential attack on the amorphous regions whereas in polypropylene this may be due to nucleation growth and lamellar thickening.

Effect of pH, temperature and nutrients on the germination of a vesicular-arbuscular mycorrhizal fungus,Glomus fasciculatum in vitro

The effect of various pH (5·5, 6·5, 7·5 and 8·5) and temperature (20, 25 and 30°C) on germination of spores ofGlomus fasciculatum on 1% water agar was studied. Maximum germination (81·3%) occurred at pH 6·5 at 25°C. Spore germination was also studied with other nutrient media such as corn meal agar, modified Hepper medium, charcoal agar (0·01%) and soil extract agar. A significant increase was observed in charcoal agar and soil extract agar (+13·4% and +10·9% respectively).

Characterization of Suppressive Immunoglobulin-Binding Factor (IBF)

Abstract The biochemical characteristics of immunoglobulin binding factor produced by activated cells (ATC) were investigated. For this purpose, supernatants of ATC were purified by affinity chromatography on insolubilized IgG and the eluted material was iodinated (125I), treated with mercaptoethanol; and run on SDS polyacrylamide gels. The radioactivity was found in two peaks corresponding to m.w. of 38,000 d and 18,000 d. This result extends and confirms our previous findings that IBF produced by ATC is identical of IBF produced by L-5178-Y internally labeled thymoma cells. The effect of various pH, temperatures, and proteolytic and glycolytic enzymes on the binding properties of 3H-leucine-or H-fucose-labeled IBF to IgG and on the poly-acrylamide gel profiles was also studied. By all these criteria, IBF appeared to be a glycoprotein in which the presence of the 38,000 to 40,000 d chain is necessary for the binding to IgG. In the attempt to study the relationships between IBF and I-region products, purified IBF produced by ATC was incubated with anti-Ia immunoadsorbent, and the eluted material was iodinated and run on gels. The 38,000 d and 18,000 d chains characteristic of IBF were found to be specifically retained on the relevant immunoadsorbent. These data favor the hypothesis that IBF bears or is associated with Ia determinants.

Neurohistological and histochemical observations on the lung of Rattus rattus rufescens (Indian black rat).

The intrinsic innervation of the lungs (right and left) has been studied by the cholinesterase technique, considering the effect of various pH, incubation periods and temperatures. Cholinergic innervation dominated. The peribronchial ganglia, large, medium-sized and irregular-shaped, rounded and small, showed a positive cholinesterase reaction. Maximum ChE activity was noticed in the bronchi and their branches and on the periphery of the alveoli.