Buffer solution

About: Buffer solution is a research topic. Over the lifetime, 6948 publications have been published within this topic receiving 112440 citations. The topic is also known as: pH buffer & buffer.

All Solid State Hydrogen Ion Selective Electrode Based on a Tribenzylamine Neutral Carrier in a Poly(vinyl chloride) Membrane with a Poly(aniline) Solid Contact

Abstract: Hydrogen ion selective solid contact electrode based on tribenzylamine have shown the best Nernstian slope, selectivity and the widest response range in Tris buffered pH sample solutions. Their linear dynamic range was pH 2.48–11.21 and Nernstian slope showed 55.1 mV/pH (at 20±0.2 °C). When it was directly applied to human whole blood (in pH range 6.0–8.5), we could get the same satisfying results. This electrode continuously contacted Tris 7.47 buffered solutions, human whole blood and hydrofluoric acid solutions for one month without any loss of performance. Especially, hydrofluoric acid did not influence the surface of this electrode, thus this electrode was maintained without showing any changes in potentials after used in hydrofluoric acid solution. The standard deviation in the e.m.f. differences determined was 1.0 mV (N=10) at Tris buffer solution of pH 6.5 and 0.5 mV at Tris buffer solution of pH 8.5. The 90 % response time of the electrodes obtained by injection of hydrochloric acid into Tris buffer sample solution was less than 8 s.

Shift of pH-Value During Thermal Treatments in Buffer Solutions and Selected Foods

Abstract: The pH value is one of the most important process parameters during thermal treatments, regardless if the medium is a simple buffer solution or a complex food matrix. When the temperature increases after an initial measurement of the pH at ambient temperature (25°C), a significant pH shift could occur, which could produce incomparable results in different buffer solutions or lead to side reactions during food preservation. Consequently, a measurement cell was constructed to record online the pH-value and temperature up to 130°C. By applying the Nernst equation, it was possible to exclude the temperature-dependent influence of the pH glass electrode on the total pH value. The pH shift was measured over a wide temperature range (ΔT 20–130°C) in the most commonly used buffer solutions and some selected food matrices. The ΔpH of certain buffer solutions, namely TRIS and ACES, showed a significant pH decrease of −2.01 ± 0.08 (ΔT 20–130°C) and −1.27 ± 0.1 (ΔT 20–130°C), respectively, whereas the pH of PBS buffe...

Electrocatalysis and Voltammetric Determination of Dopamine at a Calix[4]arene Crown‐4 Ether Modified Glassy Carbon Electrode

Abstract: A sensitive and selective electrochemical method for the determination of dopamine (DA) was developed using a calix[4]arene crown-4 ether (CACE) film modified glassy carbon electrode (GCE).The modified electrode exhibited good electrocatalytic activity for electrochemical oxidation of DA in the pH 6.00 Britton–Robinson buffer solution, and ascorbic acid (AA) did not interfere with it. The diffusion coefficient (D=2.7×10−5 cm2 s−1), and the kinetic parameter such as the electron transfer coefficient (α=0.54) of DA at the surface of CACE were determined using electrochemical approaches. The catalytic oxidation peak currents showed a linear dependence on the DA concentration and a linear analytical curve was obtained in the range of 2.0×10−5–1.0×10−3 M of DA with a correlation coefficient of 0.9990. The detection limit (S/N=3) was estimated to be 3.4×10−6 M. This method was also examined for the determination of DA in an injection sample. In addition, effects of possible interferences were investigated. The present work shows the potential of the proposed method for the fabrication of a modified electrode, as it can be effectively used for voltammetric detection of DA.

In vitro dynamic swelling behaviors of polyhydroxamic acid hydrogels in the simulated physiological body fluids

Abstract: Influence of some simulated physiological body fluids on the dynamic swelling behaviour of polyelectrolytic hydroxamic acid hydrogels (PHA) was investigated at 37 °C in vitro. The simulated physiological body fluids are distilled water, human sera, physiological saline (0.89 % NaCl), isoosmotic phosphate buffer at pH 7.4, gastric fluid at pH 1. 1, (gylicine-HCl buffer), urea (0.3 mol L−1), and the aquatic solutions of K2HPO4 and KNO3 (the sources of K+). The values of equilibrium swelling of PHA hydrogels varied in the range of 130–4625%, while the values of equilibrium fluid content of the hydrogels varied in the range of 57–97%. The initial rate of swelling, diffusional exponent, and, diffusion coefficient were calculated using swelling kinetics data. Diffusion of the fluids into the hydrogel was found to be non-Fickian character. The diffusion coefficients of the hydrogel varied between 0.6×10−6– 8.1×10−6 cm2 s−1.

Structural properties and sensing characteristics of Y2O3 sensing membrane for pH-ISFET

Abstract: The structural properties and sensing characteristics of Y2O3 sensing membrane were deposited on silicon substrates by reactive rf sputtering. The structural and morphological features of these films with annealing at various temperatures were studied by X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy. It was found that Y2O3 sensing dielectrics annealed at 800 °C exhibit a high sensitivity of 56.09 mV/pH in the solutions from pH 2 to pH 12, a low hysteresis voltage of 13.6 mV in the pH 7 → 4 → 7 → 10 → 7, and a small drift rate of 1.24 mV/h in the pH 7 buffer solution. This annealing condition is suggested for the reduction of the interfacial SiO2 and silicate formation, and the small surface roughness due to the well-crystallized Y2O3 structure.