Insights into the Retention Mechanism on a Pentafluorophenylpropylsiloxane-Bonded Silica Stationary Phase (Discovery HS F5) in RP-LC
Insights into the Retention Mechanism on a Pentafluorophenylpropylsiloxane-Bonded Silica Stationary Phase (Discovery HS F5) in RP-LC
复制标题
深入了解 RP-LC 中五氟苯基丙基硅氧烷键合二氧化硅固定相 (Discovery HS F5) 的保留机制
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发表时间：
2006
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影响因子：
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通讯作者：
C. Poole
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作者：
W. Kiridena;C. Dekay;W. W. Koziol;Z. Ali;H. Ahmed;C. Poole
溶剂化参数模型用于阐明中性化合物在含10 - 70%（v/v）有机溶剂的甲醇-水和乙腈-水移动的流动相的五氟苯基丙基异丁烷键合硅胶固定相（Discovery HS F5）上的保留机理。增加保留的主导因素是溶质尺寸和电子孤对相互作用，而极性相互作用降低保留。保留机制与基于相同二氧化硅基质且具有相似键合密度的十八烷键合二氧化硅固定相（Discovery HS C18）的比较为两种类型固定相的选择性差异提供了额外的见解。甲醇-水溶剂化的五氟苯基丙基正庚烷键合的二氧化硅固定相比十八烷基正庚烷键合的二氧化硅固定相更具内聚性和/或具有较弱的分散相互作用，并且更具偶极性/可极化性。氢键相互作用的差异对相对保留差异贡献不大。对于移动的相含有超过30%（v/v）的乙腈的选择性差异的五氟苯基丙基正戊烷键合和十八烷基正戊烷键合硅胶固定相是不超过适度的氢键酸度的差异更重要的比观察到的甲醇-水。低于30%（v/v）的乙腈选择性差异更显著，这是由于在低体积分数的乙腈下十八烷基正庚烷键合的二氧化硅固定相的不完全润湿，而这对于五氟苯基丙基正庚烷键合的二氧化硅固定相是不明显的。空间排斥影响范围更广的化合物的十八烷键合比五氟苯基丙基癸烷键合硅胶固定相与甲醇移动的相，导致额外的选择性差异比预测的溶剂化参数模型。与弱碱的静电相互作用是不重要的甲醇-水移动的相组合物，相反，乙腈-水的离子交换行为增强，特别是五氟苯基丙基异丙基硅烷键合的二氧化硅固定相。上述结果是相容的固定相构象的现象学解释，使用干草堆，表面可及性，和水连接的质子导管模型。
The solvation parameter model is used to elucidate the retention mechanism of neutral compounds on the pentafluorophenylpropylsiloxane-bonded silica stationary phase (Discovery HS F5) with methanol-water and acetonitrile-water mobile phases containing from 10 to 70% (v/v) organic solvent. The dominant factors that increase retention are solute size and electron lone pair interactions while polar interactions reduce retention. A comparison of the retention mechanism with an octadecylsiloxane-bonded silica stationary phase based on the same silica substrate and with a similar bonding density (Discovery HS C18) provides additional insights into selectivity differences for the two types of stationary phase. The methanol-water solvated pentafluorophenylpropylsiloxane-bonded silica stationary phase is more cohesive and/or has weaker dispersion interactions and is more dipolar/polarizable than the octadecylsiloxane-bonded silica stationary phase. Differences in hydrogen-bonding interactions contribute little to relative retention differences. For mobile phases containing more than 30% (v/v) acetonitrile selectivity differences for the pentafluorophenylpropylsiloxane-bonded and octadecylsiloxane-bonded silica stationary phases are no more than modest with differences in hydrogen-bond acidity of greater importance than observed for methanol-water. Below 30% (v/v) acetonitrile selectivity differences are more marked owing to incomplete wetting of the octadecylsiloxane-bonded silica stationary phase at low volume fractions of acetonitrile that are not apparent for the pentafluorophenylpropylsiloxane-bonded silica stationary phase. Steric repulsion affects a wider range of compounds on the octadecylsiloxane-bonded than pentafluorophenylpropylsiloxane-bonded silica stationary phase with methanol mobile phases resulting in additional selectivity differences than predicted by the solvation parameter model. Electrostatic interactions with weak bases were unimportant for methanol-water mobile phase compositions in contrast to acetonitrile-water where ion-exchange behavior is enhanced, especially for the pentafluorophenylpropylsiloxane-bonded silica stationary phase. The above results are compatible with a phenomenological interpretation of stationary phase conformations using the haystack, surface accessibility, and hydro-linked proton conduit models.