Results of pilot comparisons of national standards for the activity of hydrogen ions in aqueous solutions

2021 ◽  
pp. 66-72
Author(s):  
Sergey V. Prokunin ◽  
Andrey N. Shchipunov ◽  
Daria A. Vengina ◽  
Frank Bastkowskiy ◽  
Emrah Uysal ◽  
...  
Keyword(s):  
Ph Value ◽  
Aqueous Media ◽  
Phosphate Buffer Solution ◽  
Hydrogen Index ◽  
National Standards ◽  
Measuring Instruments ◽  
Buffer Solution ◽  
Working Standard ◽  
Average Value ◽  
State Register

The enormous needs in ensuring the measurement of the hydrogen index in various industries and the national economy of Russia make the measurement of the hydrogen index one of the most important methods for monitoring aqueous media. In 2013, work was carried out to enter into the State Register of Measuring Instruments of the Russian Federation a buffer solution and a standard titer with a pH value of 7.00 – a working pH standard of the 2nd category, which is one of the most demanded of non-standard solutions for verification and calibration pH measuring instruments. To confirm the metrological characteristics, pilot comparisons were organized within COOMET. This article presents the results of a pilot comparison to determine the pH of a phosphate buffer solution – a working standard of рН=7.00. 8 metrological institutes and 10 metrological organizations took part in the comparisons. The results obtained showed that the overwhelming majority of the participants in the comparisons presented the results of pH measurements, which have an uncertainty not exceeding ±0.03 of the average value, which is an acceptable criterion for measuring the pH.

Electrochemistry and Electrocatalysis of Hemoglobin Based on Graphene Quantum Dots Modified Electrode

2020 ◽  
Vol 16 (3) ◽  
pp. 308-315
Author(s):  
Xiaoyan Li ◽  
Hui Xie ◽  
Guiling Luo ◽  
Yanyan Niu ◽  
Xiaobao Li ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Modified Electrode ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Catalytic Reduction ◽  
Graphene Quantum Dots ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Detection Range ◽  
Electrochemical Behaviors

Background: Graphene quantum dots (GQD) is a new member of carbon nanomaterial that has attracted increasing attention owing to its better chemical inertness, low cytotoxicity, large specific surface area, cheap cost, suitable conductivity and excellent biocompatibility. Methods: Electrochemical behaviors of this modified electrode were studied by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical investigations of Nafion/Hb/GQD/ CILE were carried out with electrochemical parameters calculated. Results: In the phosphate buffer solution with a pH value of 5.0, good linear relationships between the catalytic reduction current and the concentration of substrate were got for TCA (6.0~100.0 mmol·L-1), NaNO2 (2.0~12.0 mmol·L-1) and H2O2 (6.0~30.0 mmol·L-1). The proposed method was applied to NaNO2 concentration detection in soak water from picked vegetables with satisfactory results. Conclusion: This Nafion/Hb/GQD/CILE had a good bioelectrocatalytic activity to different substrates such as trichloroacetic acid, NaNO2 and H2O2 reduction with the advantages including wide detection range, low detection limit and good stability. Therefore, the application of GQD in electrochemical sensor was extended in this paper.

Encapsulation of Urease in Molybdenum Trioxide Sol-Gel

2004 ◽  
Vol 828 ◽  
Author(s):  
Prashant K. Jha ◽  
P. I. Gouma
Keyword(s):  
Gas Sensing ◽  
Molybdenum Trioxide ◽  
Ph Value ◽  
Sol Gel ◽  
Microstructural Analysis ◽  
Phosphate Buffer Solution ◽  
Gaseous Ammonia ◽  
Buffer Solution ◽  
Transmission Electron ◽  
The Matrix

ABSTRACTMolybdenum trioxide sol-gel matrices were tested for their ability to host biomaterials in their structures without adversely affecting the activity of the encapsulated biomolecules. The sol-gel composites were prepared at room temperature; the urease was added during the hydrolysis step to ensure proper encapsulation in the pore structure of the sol. Phosphate buffer solution was added during this stage to maintain the pH value of the sol in the bio-compatible range. The activity of incorporated urease was tested by exposing composite sol-gel material to standard urea test solutions and measuring the amount of gaseous ammonia (released by the reaction of urea with water in the presence of urease) using an ammonia electrode. The concentration of urea solutions ranged from 1mM to 10mM. An electronic olfactory system (EOS 835) was also employed to detect the presence of gaseous ammonia. Gas sensing tests were done to verify the sensitivity of the matrix to ammonia. Microstructural analysis was carried out by means of scanning and transmission electron microscopy. It was found that urease retained its activity inside molybdenum trioxide sol-gels that are sensitive to ammonia. These hybrid nanoporous composites are useful in the field of biosensors and fuel cells.

Preparation and Drug Release Behavior from a Temperature-Sensitive Poly(aspartic Acid) Derivatives Hydrogel

2013 ◽  
Vol 711 ◽  
pp. 18-21
Author(s):  
Kui Lin Deng ◽  
Chun Xiu Li ◽  
Ting Gao ◽  
Xiao Dan Fu ◽  
Wen Hui Jin ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Aspartic Acid ◽  
Ph Value ◽  
Phosphate Buffer Solution ◽  
Temperature Sensitive ◽  
Release Behavior ◽  
Buffer Solution ◽  
Drug Release Behavior ◽  
Drug Delivery Carrier ◽  
Increasing Temperature

In this paper, a new pH/temperature-sensitive beads with semi-interpenetrating polymeric network based on sodium alginate(SA) and poly(aspartic acid) derivatives(M-E-PSI) were prepared using as drug delivery carrier. With indomethacin as a drug model，we investigated the release behaviors of indomethacin in different pH value, temperature and ratio of SA/ M-E-PSI. It turned out that the release amount of indomethacin in pH=2.1 phosphate buffer solution(PBS) was evidently higher than that in pH=7.4 PBS. And also, the release amount of indomethacin was also increased with increasing temperature and poly(aspartic acid) derivatives content in the beads.

scholarly journals The Degradation Properties of MgO Whiskers/PLLA Composite In Vitro

2018 ◽  
Vol 19 (9) ◽  
pp. 2740 ◽  
Author(s):  
Yun Zhao ◽  
Bei Liu ◽  
Hongwei Bi ◽  
Jinjun Yang ◽  
Wei Li ◽  
...  
Keyword(s):  
Ph Value ◽  
Composite Films ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
In Vitro Degradation ◽  
Final Weight ◽  
Cell Affinity ◽  
Degradation Properties ◽  
Composite Samples

In this study, composite films of stearic acid–modified magnesium oxide whiskers (Sa–w-MgO)/poly-l-lactic acid (PLLA) were prepared through solution casting, and the in vitro degradation properties and cytocompatibility of the composites with different whisker contents were investigated. The results showed that the degradation behavior of the composite samples depended significantly on the whisker content, and the degradation rate increased with the addition of MgO content. Furthermore, the degradation of the composites with higher contents of whiskers was influenced more severely by the hydrophilicity and pH value, leading to more final weight loss, but the decomposition rate decreased gradually. Furthermore, the pH value of the phosphate buffer solution (PBS) was obviously regulated by the dissolution of MgO whiskers through neutralization of the acidic product of PLLA degradation. The cytocompatibility of the composites also increased remarkably, as determined from the cell viability results, and was higher than that of PLLA at the chosen whisker content. This was beneficial for the cell affinity of the material, as it notably led to an enhanced biocompatibility of the PLLA, in favor of promoting cell proliferation, which significantly improved its bioactivity, as well.

Extraction of SOD from Alfalfa with Ultrasonic Assisted

2015 ◽  
Vol 1089 ◽  
pp. 163-166 ◽  
Author(s):  
Min Qu ◽  
Yu Jia Liu ◽  
Lin An Qin
Keyword(s):  
Specific Activity ◽  
Ph Value ◽  
Removal Rate ◽  
Orthogonal Design ◽  
Phosphate Buffer Solution ◽  
Heat Denaturation ◽  
Ultrasonic Power ◽  
Technological Parameters ◽  
Buffer Solution ◽  
Sod Activity

In this study, the new technological parameters have been optimized for running Single factor experiment and orthogonal design test. Furthermore, the optimal extractible condition of SOD activity from Alfalfa was determined by the assay of NBT photoreduction method. The results reveal that when the ratio of liquor to material is 1 to 10; pH value of phosphate buffer solution is 7.5; ultrasonic power is 400 w, therefore, the SOD activity of Alfalfa is up to 66.54 U/mL. In addition, we characterized the activity analysis of Alfalfa proteins using heat denaturation, ammonium sulfate precipitation and ultraviolet spectroscop. The results showed that the protein removal rate is approximate 91.70 % and SOD specific activity is 6.5 times. Based on the above results, we reached a preliminary estimate that the SOD from Alfalfa is a kind of Cu/Zn-SOD.

Drug Release Characteristics of P(AA-co-DMAA)/SA Interpenetrating Polymer Network Hydrogels

2011 ◽  
Vol 399-401 ◽  
pp. 1165-1168
Author(s):  
Na Na Wang ◽  
Song Bai Lin ◽  
Ke Ping Wang ◽  
Ai Ru Ke
Keyword(s):  
Reaction Time ◽  
Release Rate ◽  
Ph Value ◽  
Polymer Network ◽  
Phosphate Buffer Solution ◽  
Interpenetrating Polymer Network ◽  
Buffer Solution ◽  
Berberine Hydrochloride ◽  
Effects Of Ph ◽  
The One

P(AA-co-DMAA) superporous drug-loaded hydrogels containing berberine hydrochloride were prepared by dispersion polymerization in foam system with acrylic acid (AA) and N,N-dimethyl acrylamide (DMAA) as monomers. Then sodium alginate (SA) as the second network was added to the system, and P(AA-co-DMAA)/SA interpenetrating polymer network (IPN) hydrogels were formed. The effects of pH value, reaction time between SA and glutaric dialdehyde (GA), the concentration of SA and GA on release behavior of berberine hydrochloride were discussed. The FT-IR spectra showed that P(AA-co-DMAA)/SA IPN hydrogels were synthesized successfully. The inverted fluorescence micrograph of P(AA-co-DMAA)/SA showed that some part of the superporous structures were still retained.The cumulative release profiles showed that the release rates were slightly higher in pH=6.8 phosphate buffer solution (PBS) than the one in pH=1 HCl solution. The release rate was the slowest in distilled water, only 7.3% within 24h. When the reaction time between SA and GA was shortened, the release speed of berberine hydrochloride became faster. The pore size of P(AA-co-DMAA) hydrogels was reduced with the concentration of SA and GA increased, and the release rate decreased due to the more dense network structures.

scholarly journals A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 422
Author(s):  
Nazaruddin Nazaruddin ◽  
Nurul Afifah ◽  
Muhammad Bahi ◽  
Susilawati Susilawati ◽  
Nor Diyana Md. Sani ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Room Temperature ◽  
Ph Value ◽  
Ph Sensor ◽  
Phosphate Buffer Solution ◽  
Good Sensitivity ◽  
Buffer Solution ◽  
C Storage ◽  
Relative Standard ◽  
Optical Ph Sensor

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4oC storage. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor’s reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness.

scholarly journals Effects of Magnesium Oxide (MgO) Shapes on In Vitro and In Vivo Degradation Behaviors of PLA/MgO Composites in Long Term

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1074 ◽  
Author(s):  
Yun Zhao ◽  
Hui Liang ◽  
Shiqiang Zhang ◽  
Shengwei Qu ◽  
Yue Jiang ◽  
...  
Keyword(s):  
Magnesium Oxide ◽  
Ph Value ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Biomedical Material ◽  
Degradation Behaviors ◽  
In Vivo Degradation

Biodegradable devices for medical applications should be with an appropriate degradation rate for satisfying the various requirements of bone healing. In this study, composite materials of polylactic acid (PLA)/stearic acid-modified magnesium oxide (MgO) with a 1 wt% were prepared through blending extrusion, and the effects of the MgO shapes on the composites’ properties in in vitro and in vivo degradation were investigated. The results showed that the long-term degradation behaviors of the composite samples depended significantly on the filler shape. The degradation of the composites is accelerated by the increase in the water uptake rate of the PLA matrix and the composite containing the MgO nanoparticles was influenced more severely by the enhanced hydrophilicity. Furthermore, the pH value of the phosphate buffer solution (PBS) was obviously regulated by the dissolution of MgO through the neutralization of the acidic product of the PLA degradation. In addition, the improvement of the in vivo degrading process of the composite illustrated that the PLA/MgO materials can effectively regulate the degradation of the PLA matrix as well as raise its bioactivity, indicating the composites for utilization as a biomedical material matching the different requirements for bone-related repair.

scholarly journals Development a New Carbon Nanocomposite Containing MWCNT as Adsorbent for Effective Removal of Cloxacillin

2021 ◽  
Author(s):  
Amir-Mohammad Golkarieh ◽  
Navid Nasirizadeh ◽  
Reza Jahanmardi ◽  
Saeed Jafari ◽  
Mohammad Dehghani
Keyword(s):  
Animal Health ◽  
Sol Gel ◽  
Aqueous Media ◽  
Phosphate Buffer Solution ◽  
Maximum Efficiency ◽  
Buffer Solution ◽  
Effective Removal ◽  
Sol Gel Process ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Abstract Antibiotics along with their metabolites due to their toxicity and low biodegradability have adverse effects to human and animal health. This work can help to monitor and elimination of the residue of the cloxacillin (Clox) antibiotics in two ways: the first part involves design and fabrication of a new electrochemical nanosensor based on a screen-printed carbon electrode modified with gold nanourchin and graphene oxide for detection and determination of Clox in aqueous media. The second part focuses on the preparation of carbon nanocomposites modified with multi-walled carbon nanotubes (MWCNT/CC) as adsorbent for the removal of Clox from aqueous medium. The MWCNT/CC nanocomposites were made using sol-gel process and then the efficiency of the antibiotic removal was assessed by the designed nanosensor. In Clox removal experiments, the effect of independent variables including pH, exposure time, extent of MWCNTs and amount of adsorbent on the removal of antibiotic as a dependent variable was investigated using response surface methodology. The morphological and physical properties of the suggested adsorbent were explored. The maximum efficiency of Clox removal (97%) was achieved in conditions of using 1.52 g/L of the adsorbent fabricated by 2.9 wt. % of MWCNTs in 0.1 M phosphate buffer solution at pH of 5.0 during 75 minutes. The highest adsorption capacity of the MWCNT/CC was 296 mg/g at optimal conditions.

Sign in / Sign up

Export Citation Format

Share Document