Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 53210 Pardubice, Czech Republic.
J Chromatogr A. 2012 Jul 20;1247:89-98. doi: 10.1016/j.chroma.2012.05.076. Epub 2012 May 29.
Chromatographic behavior of block (co)oligomers of oxyethylene (EO) and oxypropylene (PO) surfactants in reversed-phase HPLC (RP-HPLC) was investigated. The retention of EO/PO block (co)oligomers depends on the distribution of the individual monomer repeat units, but the sequence of the individual blocks also plays a (less significant) role. The enthalpic and entropic contributions of the EO and PO repeat units to the retention were determined from the data measured at changing temperature. In RP-HPLC, the effect of the repeat PO units on separation is higher than the influence of the repeat EO units. In addition to the enthalpic contributions, the retention is significantly influenced by the entropy (possibly by the change of conformation and solvation of adsorbed molecules); dual molar mass distribution according to the number of EO and PO units complicates correct assignment of the chromatographic peaks to the individual (co)oligomers in complex samples based only on the chromatographic retention data. In spite of imperfect chromatographic separation, HPLC coupled with positive ion mode atmospheric pressure chemical ionization mass spectrometry allow identifying unambiguously the dual monomer distribution in the samples of EO-PO block (co)oligomers.
研究了嵌段（共）齐聚物的色谱行为氧乙烯（EO）和氧丙烯（PO）表面活性剂在反相高效液相色谱（RP-HPLC）中。EO/PO 嵌段（共）齐聚物的保留取决于各个单体重复单元的分布，但各个嵌段的序列也起着（不太重要的）作用。从不同温度下测量的数据确定了 EO 和 PO 重复单元对保留的焓和熵贡献。在反相高效液相色谱中，重复 PO 单元对分离的影响高于重复 EO 单元的影响。除了焓贡献外，保留还受到熵的显著影响（可能是由于吸附分子构象和溶剂化的变化）；根据 EO 和 PO 单元数的双重摩尔质量分布使得仅根据色谱保留数据将色谱峰正确分配给复杂样品中的各个（共）齐聚物变得复杂。尽管色谱分离不完美，但高效液相色谱与正离子模式大气压化学电离质谱联用可以明确识别 EO-PO 嵌段（共）齐聚物样品中的双重单体分布。
