Topic
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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, a simple, rapid procedure, using capillary zone electrophoresis (CZE), that can efficiently measure added folic acid in fortified instant fried noodles has been developed and validated.
37 citations
TL;DR: Experimental results showed that a solution of NaOH-KH2PO4 was comparatively suitable for the LA decarboxylation reaction by silver(I)/persulfate and a reaction scheme was proposed on basis of the reaction process.
Abstract: The oxidative decarboxylation of levulinic acid (LA) by silver(I)/persulfate [Ag(I)/S2O82−] has been investigated in this paper. The effects of buffer solution, initial pH value, time and temperature and dosages of Ag(I)/S2O82− on the decarboxylation of LA were examined in batch experiments and a reaction scheme was proposed on basis of the reaction process. The experimental results showed that a solution of NaOH-KH2PO4 was comparatively suitable for the LA decarboxylation reaction by silver(I)/persulfate. Under optimum conditions (temperature 160 °C, pH 5.0, and time 0.5 h), the rate of LA conversion in NaOH-KH2PO4 solutions with an initial concentration of 0.01 mol LA reached 70.2%, 2-butanone (methyl ethyl ketone) was the single product in the gas phase and the resulted molar yield reached 44.2%.
37 citations
TL;DR: In this article, the voltammetric behavior of uric acid was studied at a single-walled carbon nanotube (SWNT) modified gold electrode, and the experimental parameters, such as solution pH, accumulation time, and amount of SWNT, were optimized for determination.
Abstract: The voltammetric behavior of uric acid was studied at a single-walled carbon nanotube (SWNT) modified gold electrode. Uric acid can effectively accumulate at this electrode and produce an anodic peak at about 0.45 V (vs. SCE) in pH 5.0 sodium acetate buffer solutions (HAc-NaAc). The experimental parameters, such as solution pH, accumulation time, and amount of SWNT, were optimized for determination. Under the optimum conditions, the anodic peak current is linear to the uric acid concentration over the range of 1.0×10−7 M to 2.5×10−5 M with a correlation coefficient of 0.998. The detection limit was 5.0×10−8 M for 60 s accumulation. The electrode could be easily regenerated and exhibited good stability. A 5.0×10−6 M uric acid solution was measured ten times using the same electrode, and the relative standard deviation of the peak current was 1.3%. This method was successfully applied to the determination of uric acid in human urine samples, and the recovery was 97–99%. The feasibility for simultaneous determination of xanthine, ascorbic acid and uric acid was discussed. These species did not interfere with each other in a certain concentration range. The influence of some surfactants on the anodic peak was also examined.
37 citations
TL;DR: In this article, the surface sensitivity of synchrotron radiation excited photoelectron spectroscopy (SR-XPS) was used to study the surface of a sulfide mineral at different electrochemical potentials.
37 citations
TL;DR: Data indicated that hydrophobic interaction played a major role in the binding of caffeic acid to HSA in microemulsions and electrostatic interaction can not be excluded.
Abstract: In this study the interaction between gallic acid and human serum albumin (HSA) in AOT/isooctane/water microemulsions was characterized for the first time using fluorescence quenching technique in combination with UV absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy and dynamic light scattering (DLS) technique. In water-surfactant molar ratio (omega(o))=20 microemulsions fluorescence data revealed the presence of one binding site of gallic acid on HSA and its binding constants (K) were (1.18+/-0.02)x10(4), (1.13+/-0.02)x10(4), (1.03+/-0.02)x10(4), (0.95+/-0.02)x10(4), (0.87+/-0.02)x10(4) and (0.82+/-0.03)x10(4)M(-1) at 282, 289, 296, 303, 310 and 317 K, respectively. The affinities in microemulsions were much higher than that in buffer solution. FT-IR and CD data suggested that the protein conformations were altered with the reductions of alpha-helices from 54-56% for free HSA in buffer to 40-41% for free HSA in microemulsion. After binding with gallic acid, the alpha-helices of HSA in microemulsion increased 2-7% for different drug-protein molar ratio. The thermodynamic functions standard enthalpy (Delta H(0)) and standard entropy (DeltaS(0)) for the reaction were calculated to be -8.10 kJ mol(-1) and 49.42 J mol(-1)K(-1). These results indicated that gallic acid bound to HSA mainly by hydrophobic interaction and electrostatic interaction in microemulsions. In addition, the displacement experiments confirmed that gallic acid could bind to the site I of HSA, which was approved by the molecular modeling study. Furthermore, the DLS data suggested that HSA may locate at the interface of the microemulsion and gallic acid could interact with them.
36 citations