Wang Mei, Mallette Jennifer, Parcher Jon F
Chemistry Department, University of Mississippi, University, Mississippi 38677, USA.
Anal Chem. 2009 Feb 1;81(3):984-90. doi: 10.1021/ac8020104.
The experimental technique of mass spectrometric tracer pulse chromatography was used to measure the excess volume of each eluent component for binary and ternary mixtures of water, acetonitrile, and methanol on a C(18)-bonded silica RPLC packing over the full composition range. The tracer pulse method allowed the direct measurement of excess volumes of each eluent component without numerical integration, assumed isotherm equation, detector calibration, or off-line analysis of the eluent composition. Absolute isotherms were estimated from the experimental data for excess volumes by use of various strategies for the estimation of the volumes of the stationary and mobile phases in dynamic equilibrium with eluents of varying composition. The results indicate that all three eluent components interacted with the alkane bonded phase. Some components were selectively taken up as part of the stationary phase while other components were selectively excluded so the composition of eluent in or on the stationary phase often significantly differed from the composition of the bulk eluent. The exact composition of the stationary phase (bonded phase plus immobilized eluent) was dependent upon the type and composition of the bulk eluent.
采用质谱示踪脉冲色谱实验技术，在整个组成范围内，对水、乙腈和甲醇的二元及三元混合物在C(18)键合硅胶反相液相色谱填料上的每种洗脱剂组分的过量体积进行了测量。示踪脉冲法无需数值积分、假定等温方程、检测器校准或洗脱剂组成的离线分析，即可直接测量每种洗脱剂组分的过量体积。通过使用各种策略来估计与不同组成洗脱剂处于动态平衡的固定相和流动相的体积，从过量体积的实验数据中估计出绝对等温线。结果表明，所有三种洗脱剂组分均与烷烃键合相相互作用。一些组分被选择性地作为固定相的一部分被吸收，而其他组分被选择性地排除，因此固定相内部或其上的洗脱剂组成通常与本体洗脱剂的组成有显著差异。固定相（键合相加上固定化洗脱剂）的精确组成取决于本体洗脱剂的类型和组成。
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