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.

Microwave Activation of Electrochemical Processes: Square-Wave Voltammetric Stripping Detection of Cadmiumin the Presence of the Surfactant Triton X

Abstract: A novel electrochemical cell based on a flow through system in a microwave cavity is shown to allow voltammetric experiments under microwave conditions. Focusing of the microwave radiation at the electrode-solution (electrolyte) interface creates conditions of extreme localized heating with an inverted thermal gradient within the diffusion layer of the electrode and convective flow. The deposition and anodic stripping detection by square-wave voltammetry of Cd2+ in a 0.1 M acetate buffer solution is shown to be strongly enhanced by microwave activation. The temperature at the electrode-solution interface is calibrated with the reversible redox couple Ru(NH3)63+/2+ in 0.1 M acetate buffer. The effect of microwave activation on the square-wave voltammetric responses for the reduction of Ru(NH3)63+ and for the detection of Cd2+ in 0.1 M acetate buffer solution are studied. In the presence of a nonionic surfactant, Triton X-100, which blocks the electrochemical Cd2+ response under conventional conditions, microwave activation is shown to have a considerable effect in enhancing the sensitivity for Cd2+ detection.

β-Galactosidase of Aspergillus oryzae immobilized in an ion exchange resin combining the ionic-binding and crosslinking methods: Kinetics and stability during the hydrolysis of lactose

Abstract: In this work, the hydrolysis kinetics of lactose by Aspergillus oryzae β-galactosidase was studied using the ionic exchange resin Duolite A568 as a carrier. The enzyme was immobilized using a β-galactosidase concentration of 16 g/L in pH 4.5 acetate buffer and an immobilization time of 12 h at 25 ± 0.5 °C. Next, the immobilized β-galactosidase was crosslinked using glutaraldehyde concentration of 3.5 g/L for 1.5 h. The influence of lactose concentration was studied for a range of 5–140 g/L, and the Michaelis–Menten model was fitted well to the experimental results with V m and K m values of 0.71 U and 35.30 mM, respectively. The influence of the product galactose as an inhibitor on the hydrolysis reaction was studied. The model that was best fitted to the experimental results was the competitive inhibition by galactose with V m , K m and K i values of 0.77 U, 35.30 mM and 27.44 mM, respectively. The influence of temperature on the enzymatic activity of the immobilized enzyme was studied in the range of 10–80 °C, in which the temperature of the maximum activity was 60 °C, with an activation energy of 5.32 kcal/mol of lactose, using an initial concentration of lactose of 50 g/L in a pH 4.5 sodium acetate buffer solution. The thermal stability of the immobilized biocatalyst was determined to be in the range 55–65 °C. The first-order model described well the kinetics of thermal deactivation for all the temperatures studied. The activation energy of thermal deactivation from immobilized biocatalyst was 66.48 kcal/mol with a half-life of 8.9 h at 55 °C.