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.
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TL;DR: The in vitro degradation of glycine-DL-lactic acid copolymers was studied and it was concluded that the degradation was best described by hydrolysis of ester bonds via a bulk erosion process, autocatalyzed by the generated carboxylic acid end groups.
Abstract: The in vitro degradation of glycine-DL-lactic acid copolymers was studied as a function of the composition. These polydepsipeptides were prepared by ring-opening copolymerization of 6-methyl-2,5-morpholinedione and DL-lactide. The degradation of discs of the copolymers was performed in a phosphate buffer at pH 7.4 and 37°C. The decrease in molecular weight and weight was determined until complete weight loss had occurred. Poly(DL-lactide) was used as a reference material. All (co)-polymers show an immediate decrease in molecular weight, whereas the weight remains almost unchanged during a longer period of time. Decrease in weight started earlier as the glycine content of the copolymer increased. The lactic acid content of the residual material increased during the weight loss showing a higher solubility of polymer fragments with a relatively high content of glycine residues. From the hydrolysis constants it was concluded that the degradation was best described by hydrolysis of ester bonds via a bulk erosion process, autocatalyzed by the generated carboxylic acid end groups. The rate constants varied from 4-7 × 10-2 (day-1) for all (co)polymers. All (co)polymers show an increase in the molecular weight distribution upon weight loss.
47 citations
TL;DR: The addition of tertiary amines, such as triethyl amine, markedly increased the peptide yield, probably due to the increase in the concentration of the nucleophilic amine components by neutralization of hydrohalides of amino acid amides.
47 citations
TL;DR: The obtained crossover peak response for NO2- oxidation and NO reduction in pH 1.65 buffer solution gave the direct proof for the applicability of the NPyCME in the dual electrocatalytic action.
Abstract: Nafion/lead-ruthenate pyrochlore chemically modified electrode
(NPyCME) showed a remarkable dual sensing activity toward NO2−
oxidation and NO reduction as demonstrated by cyclic voltammetry (CV), ac-impedance
spectroscopy and flow injection analysis (FIA). The mechanistic parameters
of current function, charge transfer resistance and exchange current for the
NPyCME, GCE and Nafion-coated GCE were evaluated and compared. The
disproportionation reaction of NIIIO2−
into NIVO3− + NIIO in acidic
solution was used as a model system for testing the dual sensing ability of
the NPyCME. The obtained crossover peak response for NO2−
oxidation and NO reduction in pH 1.65 buffer solution gave the direct proof
for the applicability of the NPyCME in the dual electrocatalytic
action. By flow injection analysis, under optimized conditions, the calibration
curve was linear in the range of 100 nM–100 µM and 800 nM–63.3 µM
and the detection limit (S/N = 3) was 4.8 nM and 15.6 nM for NO2−
and NO, respectively.
47 citations
TL;DR: PIOP is a hydrolyzable polymer, which can be used as a cross-linker, and novel hydrogels having biodegradability and biocompatibility were prepared from poly(MPC) cross-linked with the PIOP.
47 citations
TL;DR: In this paper, the electroanalytical determination of isoprenaline in pharmaceutical preparations of a homemade carbon paste electrode modified with copper(II) hexacyanoferrate(III) (CuHCF) was studied by cyclic voltammetry Several parameters were studied for the optimization of the sensor such as electrode composition, electrolytic solution, pH effect, potential scan rate and interferences in potential.
47 citations