Improvement of polarity-based solvent system for countercurrent chromatography in the guidance of solvent selectivity: n-hexane/ethyl acetate/ alcohol solvents/water as an example
{"title":"Improvement of polarity-based solvent system for countercurrent chromatography in the guidance of solvent selectivity: n-hexane/ethyl acetate/ alcohol solvents/water as an example","authors":"","doi":"10.1016/j.chroma.2024.465389","DOIUrl":null,"url":null,"abstract":"<div><div>Solvent system selection based on polarity is a common strategy in a countercurrent chromatography (CCC) analysis. However, the solvent selectivity of solvent system is often ignored, despite its significant impact on the separation efficiency of CCC. In this study, the role of solvent in the overall properties of solvent system and the selective classification of solvent system were discussed to improve the solvent system selection based on polarity. Firstly, the mathematical relationship between logarithm of the partition coefficient (<em>log K</em>) of the template molecule and solvent composition of n-hexane/ethyl acetate/alcohol solvents (methanol, ethanol, and isopropanol)/water (HEAwat) system was analyzed and the optimal solvent system (<em>K</em> = 1) of the template molecules was determined. Then, the actual methanol concentration at the column inlet when the analyte peak in a HPLC analysis (B%) and the clustering results of the average polarity (<em>P'</em>) of the optimal CCC solvent system were analyzed. Finally, the classification of HEAWat system in terms of its overall solvent properties by deducing equations of selectivity parameters (<span><math><msub><mi>χ</mi><mi>e</mi></msub></math></span>, <span><math><msub><mi>χ</mi><mi>d</mi></msub></math></span>, and <span><math><msub><mi>χ</mi><mi>n</mi></msub></math></span>) to explain the <em>P'</em> values clustering results. The results showed that HEAWat system was suitable for the separation of analytes with 55 % < <em>B</em>% < 100 %. However, the n-hexane/ethyl acetate/isopropanol/water (HEIWat) system proved more suitable for the separation of large polar compounds to other HEAWat system when the <em>P'</em> value decreased due to the change of alcohol solvents. The selected solvent systems were classified into group III and IV by Snyder's method. The solvent systems in group III were suitable for the separation of analytes with 85 % < <em>B</em>% < 100 %, and the distribution behavior of analytes was mainly influenced by the ratio of each solvent. The solvent systems in group IV were suitable for the separation of analytes with 55 % < <em>B</em>% < 85 %, and the distribution behavior of analytes was mainly influenced by the type of alcohol solvents.</div></div>","PeriodicalId":347,"journal":{"name":"Journal of Chromatography A","volume":null,"pages":null},"PeriodicalIF":3.8000,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Chromatography A","FirstCategoryId":"1","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0021967324007635","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BIOCHEMICAL RESEARCH METHODS","Score":null,"Total":0}
引用次数: 0
Abstract
Solvent system selection based on polarity is a common strategy in a countercurrent chromatography (CCC) analysis. However, the solvent selectivity of solvent system is often ignored, despite its significant impact on the separation efficiency of CCC. In this study, the role of solvent in the overall properties of solvent system and the selective classification of solvent system were discussed to improve the solvent system selection based on polarity. Firstly, the mathematical relationship between logarithm of the partition coefficient (log K) of the template molecule and solvent composition of n-hexane/ethyl acetate/alcohol solvents (methanol, ethanol, and isopropanol)/water (HEAwat) system was analyzed and the optimal solvent system (K = 1) of the template molecules was determined. Then, the actual methanol concentration at the column inlet when the analyte peak in a HPLC analysis (B%) and the clustering results of the average polarity (P') of the optimal CCC solvent system were analyzed. Finally, the classification of HEAWat system in terms of its overall solvent properties by deducing equations of selectivity parameters (, , and ) to explain the P' values clustering results. The results showed that HEAWat system was suitable for the separation of analytes with 55 % < B% < 100 %. However, the n-hexane/ethyl acetate/isopropanol/water (HEIWat) system proved more suitable for the separation of large polar compounds to other HEAWat system when the P' value decreased due to the change of alcohol solvents. The selected solvent systems were classified into group III and IV by Snyder's method. The solvent systems in group III were suitable for the separation of analytes with 85 % < B% < 100 %, and the distribution behavior of analytes was mainly influenced by the ratio of each solvent. The solvent systems in group IV were suitable for the separation of analytes with 55 % < B% < 85 %, and the distribution behavior of analytes was mainly influenced by the type of alcohol solvents.
期刊介绍：
The Journal of Chromatography A provides a forum for the publication of original research and critical reviews on all aspects of fundamental and applied separation science. The scope of the journal includes chromatography and related techniques, electromigration techniques (e.g. electrophoresis, electrochromatography), hyphenated and other multi-dimensional techniques, sample preparation, and detection methods such as mass spectrometry. Contributions consist mainly of research papers dealing with the theory of separation methods, instrumental developments and analytical and preparative applications of general interest.
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