Universidade Estadual de Campinas (UNICAMP), Faculdade de Engenharia de Alimentos (FEA), Departamento de Ciência de Alimentos, Rua Monteiro Lobato 80 (Cidade Universitária Zeferino Vaz), P.O. Box 6121, 13083-970 Campinas, SP, Brazil.
J Chromatogr A. 2012 Mar 2;1227:174-80. doi: 10.1016/j.chroma.2012.01.001. Epub 2012 Jan 8.
The effects of mobile phase pH, temperature, buffer type and buffer concentration on the selectivity and stability of four stationary phases, with different PMOS loadings, prepared by the thermal immobilization of poly(methyloctylsiloxane) on to silica (PMOS-SiO₂), were evaluated with both hydrophobic and hydrophilic basic solutes. These solutes show longer retention times at near neutral pH, where both the silanols and the basic solutes are partially ionized, and shorter retention times in more alkaline pH, where the silanols are mostly ionized and the basic solutes are not ionized. Increases in temperature and buffer concentration also result in shorter retention times. These PMOS-SiO₂ stationary phases are quite stable at low pH and are also stable at ambient temperature (23 °C) using pH 7 phosphate. The PMOS-SiO₂ stationary phases are more stable at higher pH using triethylamine (pH 11) and borate (pH 10) buffers than with phosphate and carbonate buffers. Temperature increases stationary phase degradation, while buffer concentration has a minimal effect on stationary phase degradation, indicating that these PMOS-SiO₂ stationary phases have stabilities similar to the equivalent chemically bonded phases.
考察了四种不同 PMOS 负载的聚（甲基辛基硅氧烷）通过热固定在二氧化硅上（PMOS-SiO₂）制备的固定相，在水相和亲水性碱性溶质存在下，流动相 pH、温度、缓冲液类型和浓度对其选择性和稳定性的影响。这些溶质在接近中性 pH 时保留时间较长，此时硅醇和碱性溶质部分电离，而在碱性更强的 pH 时保留时间较短，此时硅醇大部分电离而碱性溶质不电离。升高温度和缓冲液浓度也会导致保留时间缩短。这些 PMOS-SiO₂固定相在低 pH 下非常稳定，在环境温度（23°C）下使用 pH 7 磷酸盐时也很稳定。与磷酸盐和碳酸盐缓冲液相比，在更高 pH 值下使用三乙胺（pH 11）和硼酸盐（pH 10）缓冲液时，PMOS-SiO₂固定相更稳定。温度升高会导致固定相降解，而缓冲液浓度对固定相降解的影响很小，这表明这些 PMOS-SiO₂固定相具有与等效化学键合相相似的稳定性。
