scholarly journals Application of secondary pH measurement method for homogeneity and stability assessment of reference materials

2021 ◽  
Author(s):  
Boryana Koleva ◽  
Lyudmila Dimitrova ◽  
Daniela Stoica ◽  
Paola Fisicaro
Keyword(s):  
Small Volume ◽  
Phosphate Buffer Solution ◽  
Ph Measurement ◽  
Stability Assessment ◽  
Buffer Solution ◽  
Testing Laboratories ◽  
Proficiency Testing Schemes ◽  
Buffer Solutions ◽  
Ph Values

AbstractIn this work, the development and optimization of a secondary method for pH measurement using a differential potentiometric cell are described. The method was optimized and validated by measurement of three certified primary buffer solutions (CRMs) with nominal pH values of 4.005, 6.865 and 9.180 at 25 °C. The method was applied to assess homogeneity and stability of phosphate buffer solution with nominal pH of 7.000 at 25 °C which will be used as test item in proficiency testing schemes for pH measurement of testing laboratories. The experiments carried out and described in this article proved that this particular design of secondary differential potentiometric cell requires small volume of solutions, is fast, accurate and precise and is suitable for the characterization of secondary buffer solutions and assessment of homogeneity and stability of buffer solutions.

Bioceramic Hydroxyapatite Granules for Purification of Biotechnological Products

2011 ◽  
Vol 284-286 ◽  
pp. 1764-1769 ◽  
Author(s):  
Vitalijs Lakevics ◽  
Janis Locs ◽  
Dagnija Loca ◽  
Valentina Stepanova ◽  
Liga Berzina-Cimdina ◽  
...  
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Phosphate Buffer ◽  
Bovine Serum ◽  
Phosphate Buffer Solution ◽  
Sorption Process ◽  
Buffer Solution ◽  
Ph Values ◽  
Bovine Serum Albumin Adsorption ◽  
Albumin Adsorption

Sorption experiments of bovine serum albumin (BSA) on hydroxyapatite (HAp) ceramic granules, prepared at three temperatures 900°C, 1000°C and 1150°C were performed at room temperature 18,6 °C and phosphate buffer, pH 5,83; 6.38 and 7,39. Thermal treatment contributed to the decrease of bovine serum albumin immobilization indicating that sorption process depended on HAp ceramics specific surface area and pH values of phosphate buffer solution. However, it was confirmed that granule size was also an important parameter for bovine serum albumin adsorption. As a result of these experiments, the most appropriate adsorption conditions and phosphate buffer pH values influence on to BSA sorption were analyzed.

Morphological and Electrical Properties of Silicon Dioxide-Based Interdigitated Electrode Arrays

2015 ◽  
Vol 1109 ◽  
pp. 253-256 ◽  
Author(s):  
M.A. Farehanim ◽  
U. Hashim ◽  
Norhayati Soin ◽  
A.H. Azman ◽  
S. Norhafiezah ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Silicon Dioxide ◽  
Ph Value ◽  
Ph Measurement ◽  
Electrode Arrays ◽  
Interdigitated Electrode ◽  
Buffer Solutions ◽  
Ph Values ◽  
Ph Buffer ◽  
Higher Sensitivity

The electrical performances of silicon dioxide-based Interdigitated electrodes (IDEs) as biosensor were developed. The IDEs was made up by two individually addressable Interdigitated comb-like finger structure have frequently been suggested as a biosensor which promises higher sensitivity compared to conventional parallel electrodes. The purpose of this paper was to investigate the capacitance test and impedance test to taken with various pH solution to observe the response of the sensor with different pH values. Purchased pH buffer solutions which varied from pH2 to pH10 are dropped on the microelectrode and the effect on it is investigated for the application in pH measurement. This research has proven that increase in pH value from acidic to alkaline is proportional with capacitance. The measured values of capacitance with respect to each pH concentrations applied during the measurements were repeatable and reproducible.

scholarly journals THE PROPERTIES OF MAMMALIAN STRIATED MYOFIBRILS ISOLATED BY AN ENZYMATIC METHOD

1950 ◽  
Vol 91 (6) ◽  
pp. 655-664 ◽  
Author(s):  
Armin F. Schick ◽  
George M. Hass
Keyword(s):  
Ionic Strength ◽  
Potassium Chloride ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Potassium Phosphate ◽  
Microscopic Structure ◽  
Buffer Solution ◽  
Buffer Solutions ◽  
Alkaline Side ◽  
Fresh Frozen

A new method for the isolation of large numbers of individual myofibrils from fresh mammalian skeletal and cardiac muscle has been described. Purification of isolated myofibrils was accomplished by differential centrifugation of fresh frozen sections of muscle which had been mechanically agitated after exposure for 30 to 45 minutes at 0°C. to the action of a dilute solution of trypsin in a phosphate buffer solution with a pH of 7.0 and an ionic strength of 0.25. Isolated skeletal myofibrils of the rabbit and man have similar constant solubility properties. They dissolve in an aqueous mixture of 0.5 N potassium chloride and 0.03 N sodium bicarbonate, giving viscous solutions which exhibit conspicuous birefringence of flow. They are soluble in buffer solutions (ionic strength 0.15) on the acid side of pH 4 and alkaline side of pH 10. If the ionic strength of potassium phosphate buffer solutions is increased to 0.5 or if the ionic strength of phosphate-borate buffer solutions is increased to a similar value by addition of potassium chloride, the isolated myofibrils become soluble at neutrality. Hence, it is possible, first to isolate the myofibrils and then dissolve them without deviating appreciably from physiologic ranges of pH. The extent to which myofibrils are modified by the conditions imposed by the method of isolation is unknown. There is no significant change in microscopic structure or optical birefringence. Furthermore, there is retention of a form of physiological reactivity, for when the isolated skeletal myofibrils are immersed in solutions of adenosinetriphosphate, they promptly and irreversibly change from elongated fibrils with distinct structural detail into dense spherical masses without recognizable microscopic structure.

scholarly journals Solubility Enhancement of Clozapine Through Co-Crystal Formation with Isonicotinamide

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Fikri Alatas ◽  
Hestiary Ratih ◽  
Hesti Kurnia ◽  
Sundani Nurono Soewandhi
Keyword(s):  
Dissolution Rate ◽  
Phosphate Buffer Solution ◽  
Crystal Formation ◽  
X Ray Diffraction ◽  
High Permeability ◽  
Buffer Solution ◽  
Pxrd Pattern ◽  
Low Solubility ◽  
Biopharmaceutical Classification System

Clozapine (CLO) is an effective atypical antipsychotic to control the symptoms of psychosis and schizophrenia. Clozapine has low solubility and high permeability, so it is classified as a class II in the biopharmaceutical classification system. The aim of this study was to improve the solubility and dissolution rate of clozapine by clozapine-isonicotinamide (CLO-INA) co-crystal formation. CLO-INA co-crystal was prepared by solvent-drop grinding (SDG) method using water as a solvent. Characterization of SDG result was conducted by powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR).  Solubility test was performed in water at room temperature. The dissolution test was performed in 900 mL of pH 6.8 phosphate buffer solution, 50 rotation per minute of paddle rotation, and at 37±0.5 °C. The PXRD pattern of  SDG result of CLO-INA has many different peaks from its parent components, and this may indicate the co-crystal formation. The solubility of the co-crystal clozapine was fifteen folds higher than pure clozapine. The dissolution rate of CLO-INA co-crystal increased in the first 10 minutes compared to pure clozapine. Percentage of clozapine dissolved after 10 minutes from CLO-INA co-crystal and pure CLO were 10.2 and 2.4%, respectively. CLO and INA can form co-crystal by SDG method that can improve the solubility and dissolution rate of clozapine.Keywords: Clozapine, Isonicotinamide, Co-crystal, Solubility, Dissolution

Effect of pH Values on Conversion of Calcite Crystals into Calcium Phosphate Phases in Buffer Solutions

2007 ◽  
Vol 353-358 ◽  
pp. 2183-2186 ◽  
Author(s):  
Ya Ping Guo ◽  
Bao Qiang Li ◽  
Yu Zhou ◽  
De Chang Jia
Keyword(s):  
Calcium Phosphate ◽  
Ph Value ◽  
Octacalcium Phosphate ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Buffer Solution ◽  
Effect Of Ph ◽  
X Ray ◽  
Buffer Solutions ◽  
Ph Values

Calcium phosphate phases with laminar-plate structure were converted from calcite powders after soaking in phosphate buffer solutions of pH’s 6.0-8.0 at 37 °C for 9 days. The effect of pH values on the conversion of calcite crystals was investigated by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. If the pH value of a buffer solution is kept at 6.0, calcite powders are converted mainly to dicalcium phosphate dehydrate (DCPD) or octacalcium phosphate (OCP). If the pH value is kept at 6.4 or 7.0, calcite powders are converted mainly to OCP. Hydroxyapatite (HAP) with poorly crystalline can be obtained from calcite powders both by treatment of a basic buffer solution, and by treatment of an acid buffer solution without regulating its pH value during the reaction. The conversion mechanism of calcite crystals is a dissolution-precipitation reaction.

scholarly journals Electrocatalytic activity for dopamine of silver nanoparticle onto graphene/poly(1,8-diaminonaphthalene) electrodes

2020 ◽  
Vol 9 (1) ◽  
pp. 111-115
Author(s):  
Hung Giap Van ◽  
Huy Nguyen Le ◽  
Van Bui Thi Hong ◽  
Dung Nguyen Tuan ◽  
Mai Nguyen Thi Tuyet
Keyword(s):  
Electrocatalytic Activity ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Modified Glassy Carbon Electrode ◽  
Buffer Solution ◽  
Structural Morphology ◽  
Graphene Composite ◽  
Novel Approach ◽  
Pulse Voltammetry

In this research, we report on the synthesis and electrochemical characterization of a poly(1,8-diaminonaphthalene)/graphene composite film which is capable to adsorb Ag+ ions toward to the dopamine sensing application. The present of graphene significantly improved the structural morphology and electrochemical activities of the pristine polymer, the adsorption capacity for Ag+ ions and the conductivities of the composite were enhanced. The graphene/poly(1,8-diaminonaphthalene)-Ag modified glassy carbon electrode was used to the ability of electrocatalytic activity dopamine in phosphate buffer solution by differential pulse voltammetry. The results open up the path for designing other dopamine sensing based on our novel approach.

scholarly journals The Use of Tungsten in Potentiometry to Detect Pospat Baffer and Urease Enzyme

2021 ◽  
Vol 7 (3) ◽  
pp. 325
Author(s):  
Victor H Sihombing ◽  
Abd Hakim S
Keyword(s):  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Electrolyte Solutions ◽  
Indicator Electrode ◽  
State University ◽  
Buffer Solution ◽  
Urea Content ◽  
Ftir Characterization ◽  
Urease Enzyme

This study aims to characterize phosphate buffer and urease enzymes through the absorbance spectrum of UV-Vis and FTIR using tungsten as the indicator electrode. The method used in this research is the biosensor potentiometric method carried out in the Laboratory of the Faculty of Mathematics and Natural Sciences, State University of Medan and the Beacukai Belawan Medan laboratory. The absorbance characterization of electrolyte solutions in various compositions using UV-Vis showed that phosphate buffer solution 0.001 M pH 7.5+KCl 0.001 M + urea 0.001 M+3 drops urease enzyme had the highest absorbance compared to electrolyte solutions with phosphate buffer and urea content. Likewise, the FTIR results showed the same thing where phosphate buffer solution was 0.001 M pH 7.5 + KCl 0.001 M + urea 0.001 M + 3 drops urease enzyme had the highest% T (transmission) pattern of phosphate buffer solution and urea. The urease enzyme in this study functions as a catalyst. Based on UV-Vis and FTIR characterization, it was concluded that the phosphate buffer solution of 0.001 M pH 7.5+KCl 0.001 M + urea 0.001 M + 3 drops of urease enzyme was the best.

Disk-Sphere Transformation in Mammalian Red Cells

1940 ◽  
Vol 17 (2) ◽  
pp. 117-127
Author(s):  
ROBERT F. FURCHGOTT ◽  
ERIC PONDER
Keyword(s):  
Fatty Acid ◽  
Cell Surface ◽  
Serum Albumin ◽  
Blood Cells ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Red Cells ◽  
Red Cell ◽  
Buffer Solution ◽  
Ph Values

1. Experimental evidence has been presented showing that crystalbumin (the carbohydrate-poor fraction of serum albumin) is the factor which prevents mammalian red blood cells from becoming spherical at pH values over 9.2. 2. The amount of crystalbumin taken up from a solution of it by red cells previously freed of it is of the order of 800 mg. per 100 c.c. of red cells. If this amount is all taken up at the red cell surface, it would form a layer only a few molecules thick. 3. The electrophoretic mobility in phosphate buffer of pH 7.4 is the same for cells containing crystalbumin, cells free of crystalbumin, cells with anti-sphering activity counteracted by fatty acid, and ghosts which have been temporarily sphered by a rise in pH. The mobilities in a saline-glycine buffer solution of pH 10.1 for the first three classes of cells just mentioned are also the same. The mobility of cells sphered with lecithin in a saline-phosphate buffer solution is the same as that for untreated discoidal cells.

scholarly journals Electrochemical characterization of 1,5-benzodiazepine oximes in organic solvents

Chemija ◽  
2018 ◽  
Vol 29 (4) ◽  
Author(s):  
Lina Rekovič ◽  
Lidija Kosychova ◽  
Irina Bratkovskaja ◽  
Viltė Žukauskaitė ◽  
Regina Vidžiūnaitė
Keyword(s):  
Molecular Structures ◽  
Acetate Buffer Solution ◽  
Carbon Electrode ◽  
Oxidation Peak ◽  
Buffer Solution ◽  
Electron Transfer Process ◽  
Ph Values ◽  
Oxidation Potentials ◽  
Cyclic Voltammetry Method

Six novel 1,3,4,5-tetrahydro-2H-1,5-benzodiazepine oximes (1–6) were electrochemically characterized on a glassy carbon electrode by the cyclic voltammetry method in different solvents, at different pH values and varying the potential scan rate. The well-defined first anodic peak was observed in the solvents used and acetate buffer solution while the second oxidation peak was dimished or absent for all studied compounds. All compounds were irreversibly oxidized at positive potentials. The electron transfer process for all investigated compounds was controlled by diffusion. Oxidation potentials were dependent on the molecular structures of investigated compounds as well as on the solvent nature.

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