在脂肪酸-水流动相中小分子在反相高效液相色谱中的保留表征

在反相液相色谱(RPLC)中用Snyder经验议程和计量置换保留模型(SDM-R)中的参数对深质为脂肪醇同系物,流动相为脂肪酸同系物时深质的保留行为进行了研究,结果表明用SDM-R参数具有明显的优越性,另外,由于用Snyder经验公式中二参数之间的作园无法准确求得斜率,且其不具有明确的物理意义,而由SDM-R二参数作图,不但能准确求得斜率j(与1mol溶剂和固相结合能有关的常数),而且j具有明确的物理意义并符合碳数规律,所以,参数j有可能用于RPLC中表征深剂强度,由此得出,在RPLC中,对同一置换剂面言,随同系物溶质的Z(1mol深剂化深质被深剂化固定相吸附时,从二接解面释放出的置换剂分子数)和logI(与1mol深质和固定相亲和势有关的常数)值增大,它们的保留时间也增大,对同一深质而言,随着在同系物置换剂中碳链的增长,Z和logI值的减小,它的保留时间也缩短,同时还可得出,随着同系物置换剂j值的减小,它们的洗脱能力也增强.

The Characterization of Retention Behaviours of Small Molecules on Reversed-phase Liquid Chromatographic Column in Mobile Phase of n-Fatty Acid-Water System

The retention behaviours of n-aliphatic alcohols with mobilephase of n-aliphatic acids-water in reversed-phase liquid chromatography (RPLC) were studied with stoichiometric displacement model for retention (SDM-R) and Snyder′s empirical equation. The results obtained showed that SDM-R was superior to Snyder′s empirical equation when they were employed to characterize the retention behaviours of homologue and the solvent strength of homologous displacers. The slope, 1/q, of the plot of logK0w versus S has no clear physical meaning and can not be measured accurately, while the slope, j (a constant relating to the affinity of 1 mole solvent to bonded stationary phase ), of the plot of logI (a constant relating to the affinity of 1 mole of solute to bonded stationary phase) versus Z (the number of solvent molecules released from the contact surface region of 1 mole of solvated solute absorbed onto solvated bonded stationary phase) is not only determined accurately but also has a clear physical meaning and follows the rule of carbon number. Therefore, if it is possible, j can be used to characterize the solvent strength employed in RPLC. The conclusion is that with a given displacer, the retention of homologue in RPLC increases with their Z and logI increasing. If a solute is given, with the increment in carbon chain of homologous displacers, the values of Z and logI of the solute decrease and thus lead to the decrease of the solute retention, and the elution strength of a solvent becomes strong as the j value of a homologous displacer becomes small.