Systematic approach to links between separations in MEKC and reversed-phase HPLC
Systematic approach to links between separations in MEKC and reversed-phase HPLC
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DOI：
10.1021/ac980308x
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发表时间：
1998-10-01
影响因子：
7.4
通讯作者：
Loran, JS
中科院分区：
文献类型：
--
作者：
Ferguson, PD;Goodall, DM;Loran, JS
比较了一系列烷基苯和取代苯酚在胶束电动色谱（MEKC）和反相高效液相色谱（RP-HPLC）中的保留因子和分配系数。在这两种技术中，分离都是基于水相和烷基相之间的分配。在MEKC中，这是SDS（C12）胶束假固定相，而在RP-HPLC中，这是ODS 2（C18）固定相。使用无孔二氧化硅（Micra 1.5 μ m），其碳载量较低，而不是标准多孔二氧化硅，以避免HPLC中的过量保留，并允许在两种分离模式中使用相同的移动的相条件。发现分析物保留因子的平均比率k（MEKC）：k（HPLC）等于比率β（MEKC）：β（HPLC），其中β是相比率。这意味着分配系数P在MEKC和HPLC中相似，因为P = k/β，并且对每个烷基相中的稳定性的主要贡献来自两种分离介质共有的疏水相互作用。由于在水性缓冲液条件下MEKC和HPLC中的分配系数相似，因此只要已知相比例，一种技术中的保留信息可以转移到另一种技术中;在MEKC和HPLC中，在已知相比例的情况下，对供试化合物的log辛醇-水分配系数K-ow与log k的线性相关性进行转换，以得到log P值作为log K-ow的函数。这使得MEKC和HPLC之间的定量联系可以扩展到包括辛醇-水分配。发现在0-20%（v/v）浓度范围内添加乙腈作为有机改性剂对HPLC中的k比MEKC中的k具有更大的影响，这可能是由于临界胶束浓度增加而导致MEKC相比例降低的结果。
Retention factors and partition coefficients in micellar electrokinetic chromatography (MEKC) and reversed-phase high-performance liquid chromatography (RP-HPLC) are compared for a series of alkylbenzenes and substituted phenols. In both techniques, separations are based on partitioning between an aqueous phase and an alkyl phase, In MEKC,this was an SDS (C12) micellar pseudostationary phase, and in RP-HPLC an ODS 2 (C18) stationary phase. A nonporous silica (Micra 1.5-mu m NPS); which has a low carbon loading, was used rather than a standard porous silica to avoid excessive retention in HPLC and to allow identical mobile phase conditions to be used in both separation modes. The average ratio of analyte retention factors, k(MEKC):k(HPLC), was found to be equal to the ratio beta(MEKC):beta(HPLC), where beta is the phase ratio. This implies that partition coefficients, P, are similar in both MEKC and HPLC, since P = k/beta, and that the dominant contribution to stability within each alkyl phase arises from hydrophobic interactions which are common to both separation media. Since partition coefficients are similar in MEKC and HPLC under aqueous buffer conditions, information on retention in one technique may be transferred to the other, provided that the phase ratios are known; In MEKC and HPLC, linear correlations of log octanol-water partition coefficients, K-ow, vs log k for the test compounds were transformed, knowing the phase ratio, to give log P values as a function of log K-ow. This allows quantitative links between MEKC and HPLC to be extended to include octanol-water partitioning. The addition of acetonitrile as an organic modifier over the concentration range 0-20% (v/v) was found to have a greater effect on k in HPLC than in MEKC, This could be a result of a decrease in the MEKC phase ratio due to an increase in the critical micelle concentration.