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.

The role of intrinsic binding rate and transport rate in the adsorption of prothrombin, albumin, and fibrinogen to phospholipid bilayers

Abstract: The rates of adsorption and desorption of prothrombin, albumin, and fibrinogen are studied by means of ellipsometry. The adsorbing surface consists of a chromium slide covered with a bilayer of negatively charged phospholipid (dioleoylphosphatidylserine) in a stirred buffer solution. Using an unstirred layer model, a simple graphical representation of the results is presented which allows detection of a transport limitation in sorption kinetics and also allows direct estimation of the thickness δ of the unstirred layer. Values of δ ranged from 2.5 to 10 μm, depending on the rate of stirring. The initial rate of prothrombin adsorption is transport-limited under all conditions studied. Adsorption of fibrinogen is much slower and determined by the intrinsic rate of protein binding. However, the adsorption becomes faster after lowering the pH and ionic strength of the buffer solution and eventually becomes transport-limited. Adsorption of albumin is slow and determined by the intrinsic binding rate for all conditions studied. Reversible adsorption is demonstrated for prothrombin, while the adsorption of fibrinogen and albumin was apparently irreversible.

Voltammetric Determination of Folic Acid with a Multi-Walled Carbon Nanotube-Modified Gold Electrode

Abstract: The voltammetric behavior of folic acid (FA) at a multi-walled carbon nanotube (MWNT) modified gold electrode has been investigated by cyclic voltammetry, chronoamperometry and chronocoulome- try. The modified electrode exhibits a good promoting effect on the electrochemical reaction of FA. FA can generate a well-defined anodic peak at around 0.83 V (vs. SCE) in 0.1 M H3PO4-NaH2PO4 buffer solution of pH 2.5. The peak results from a 2-electron transfer of FA, and the standard potential of FA is estimated to be 0.79 V (vs. SCE). The parameters affecting the re- sponse of FA, such as solution pH, accumulation time, accumulation potential, and amount of MWNTs are optimized for the determination of FA. Under the opti- mum conditions, the peak current changes linearly with FA concentration in the range from 2.0� 10 � 8 Mt o 1.0� 10 � 6 M. This method has been applied to the determination of FA in drug tablets, and the recovery is 93.9-96.9%. In addition, the influence of some co- existent species is examined. When a Nafion layer is introduced on the gold electrode before deposition of MWNTs, the resulting composite electrode can give better response to FA. At the same time, the interference by some foreign species is suppressed to some extent.