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.

Electrocatalysis of Anodic Oxygen‐Transfer Reactions: The Electrochemical Incineration of Benzoquinone

Abstract: The electrochemical performance of several anode materials is compared for the electrochemical incineration of p-benzoquinone in acetate buffer media (pH 5). The chemical oxygen demand (COD) estimated for benzoquinone by titration with standard permanganate solution can be decreased to virtually zero by electrolysis at electrodes comprised of Fe(III)-doped {beta}-PbO{sub 2} films on Ti substrates. Carbon dioxide is a product of the electrochemical process; however, the possibility of other volatile products cannot be dismissed. Addition of solid benzoquinone to acetate media is followed by slow formation of a brownish black color that is concluded to result from one or more humic compounds produced by condensation of benzoquinone; however, it cannot be concluded whether the condensation reaction is a necessary prerequisite to successful electrochemical incineration of benzoquinone. Optimal operating conditions suggested for electrochemical incineration of benzoquinone in acetate buffer include heating of the anode (e.g., 60 C) to increase the rate of anodic discharge of H{sub 2}O and, thereby, decrease the anodic overpotential. Evidence also is presented that the rate of electrochemical incineration is enhanced slightly by the addition of a traces of Fe(III) with reduction of dioxygen (O{sub 2}) to hydrogen peroxide (H{sub 2}O{sub 2}) at a cooled stainless steel cathodemore » (e.g., 15 C) in an undivided cell.« less

Capillary electrophoresis of DNA restriction fragments with solutions of entangled polymers.

Abstract: Separation of DNA restriction fragments in dilute buffer solutions of network forming polymers such as linear polyacrylamide (PAA), hydroxyethyl cellulose (HEC) and polyvinylalcohol (PVA) in phosphate buffer were investigated. PVA in buffers already became inhomogeneous after a few separations with resultant deterioration of resolution. Hydroxylic polymers, capable of forming suitable networks in buffers, are strongly adsorbed to fused silica surfaces suppressing the electroosmotic flow. These polymers could be applied as surface modifiers in capillaries, filled with buffer media containing other polymers such as PAA: Suppression of the electroosmotic flow by adsorbed HEC at pH 7 was slightly more effective than with PVA but the former coating was less stable due to weaker binding to the fused silica surface. Good separations of restriction fragments could be achieved with solutions of PAA or HEC as separation media after surface pretreatment of fused silica capillaries by either PVA rinsing or coating according to Hjerten [41].

Potentiometric enzyme electrode for urea determination using immobilized urease in poly(vinylferrocenium) film

Abstract: A new enzyme electrode for the determination of urea was developed by immobilizing urease in poly(vinylferrocenium) (PVF+) matrix. A PVF+ClO4− film was coated on Pt electrode at +0.7 V by electrooxidation of poly(vinylferrocene) in metylene chloride containing 0.1 M tetrabutylammonium perchlorate (TBAP). The enzyme modified electrode PVF+E− was prepared by anion-exchange in an enzyme solution in 1.0 mM phosphate buffer at pH 7.0. FTIR spectroscopy was used to identify PVF+ClO4−, and PVF+E−. UV spectroscopy was also used to prove the enzyme immobilization. The effects of polymeric film thickness, concentration of enzyme solution, immobilization time of the enzyme, pH and temperature of the medium, concentration of the buffer solution and possible interferents on the measured potential values were investigated. The potentiometric enzyme electrode developed in this study provided linearity to urea in the 5 × 10−5 to 1 × 10−1 M urea concentration range. The detection limit under the optimum working conditions was determined as 5 × 10−6 M for urea. The enzyme electrode was found to be stable for 24 days. The apparent Michaelis-Menten consant (KM app) value and the activation energy, Ea, of this immobilized enzyme system were found to be 4.48 × 10−5 M and 4.97 kcal mol−1 for urea, respectively.