Evaluation of protonation constants of glycylglycine in acetonitrile– and ethylene glycol–water mixtures

Q3 Chemical Engineering Chemical Speciation and Bioavailability Pub Date : 2015-07-03 DOI:10.1080/09542299.2015.1087161

Bogi Srinu, V. Gowri Kumari, C. Nageswara Rao, B. Sailaja

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Abstract

Abstract Knowledge of the protonation constants of dipeptides is important and necessary for complete understanding of their physiochemical behavior. The effect of dielectric constant of medium on protonation equilibria has been studied by determining protonation constants of glycylglycine pH-metrically in various concentrations (0–60%v/v) of acetonitrile–water and ethylene glycol–water mixtures, at an ionic strength of 0.16 mol L−1 and at 303.0 ± 0.1 K. The protonation constants were calculated with the computer program MINIQUAD75 and selection of the best fit chemical models is based on the statistical parameters. Linear and non-linear variations of stepwise protonation constants with reciprocal of dielectric constant of the solvent mixtures have been attributed to the dominance of electrostatic and non-electrostatic forces, respectively. Distribution of species, protonation equilibria, and effect of influential parameters on the protonation constants have also been presented.

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甘氨酸在乙腈和乙二醇-水混合物中质子化常数的评定

摘要了解二肽的质子化常数对于完全理解其物理化学行为是非常重要和必要的。在离子强度为0.16 mol L−1和303.0±0.1 K条件下，通过测定不同浓度(0-60%v /v)乙腈-水和乙二醇-水混合物中甘氨酸的质子化常数，研究了介质介电常数对质子化平衡的影响。用计算机程序MINIQUAD75计算质子化常数，并根据统计参数选择最适合的化学模型。质子化常数随介质常数倒数的线性和非线性变化分别归因于静电和非静电力的主导作用。本文还介绍了物质的分布、质子化平衡和影响参数对质子化常数的影响。

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Chemical Speciation and Bioavailability 环境科学-毒理学

CiteScore

1.62

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0.00%

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审稿时长

1 months

期刊介绍： Chemical Speciation & Bioavailability ( CS&B) is a scholarly, peer-reviewed forum for insights on the chemical aspects of occurrence, distribution, transport, transformation, transfer, fate, and effects of substances in the environment and biota, and their impacts on the uptake of the substances by living organisms. Substances of interests include both beneficial and toxic ones, especially nutrients, heavy metals, persistent organic pollutants, and emerging contaminants, such as engineered nanomaterials, as well as pharmaceuticals and personal-care products as pollutants. It is the aim of this Journal to develop an international community of experienced colleagues to promote the research, discussion, review, and spread of information on chemical speciation and bioavailability, which is a topic of interest to researchers in many disciplines, including environmental, chemical, biological, food, medical, toxicology, and health sciences. Key themes in the scope of the Journal include, but are not limited to, the following “6Ms”: Methods for speciation analysis and the evaluation of bioavailability, especially the development, validation, and application of novel methods and techniques. Media that sustain the processes of release, distribution, transformation, and transfer of chemical speciation; of particular interest are emerging contaminants, such as engineered nanomaterials, pharmaceuticals, and personal-care products. Mobility of substance species in environment and biota, either spatially or temporally. Matters that influence the chemical speciation and bioavailability, mainly environmentally relevant conditions. Mechanisms that govern the transport, transformation, transfer, and fate of chemical speciation in the environment, and the biouptake of substances. Models for the simulation of chemical speciation and bioavailability, and for the prediction of toxicity. Chemical Speciation & Bioavailability is a fully open access journal. This means all submitted articles will, if accepted, be available for anyone to read, anywhere, at any time. immediately on publication. There are no charges for submission to this journal.