Institute of Chemistry, University of Campinas, Campinas, SP, Brazil.
J Sep Sci. 2011 May;34(10):1141-8. doi: 10.1002/jssc.201000700. Epub 2011 Apr 13.
The chromatographic behaviors of some basic solutes were evaluated on stationary phases based on poly(methyloctylsiloxane) immobilized onto silica (PMOS-SiO(2)). The test solutes present both hydrophobic and hydrophilic properties. Evaluations of the pH effect used 80:20 v/v methanol/buffered mobile phase over the pH range of 5-11.5 with inorganic buffers such as borate, carbonate and phosphate and with organic buffers such as citrate, tricine and triethylamine. Evaluations in acidic mobile phases used 50:50 v/v and 30:70 v/v methanol/buffer (pH 2.5; 20 mmol/L) mobile phases. The buffer concentration effect used 65:35 v/v methanol/phosphate (pH 7; 20 and 100 mmol/L) mobile phases. The results are compared with those obtained with two chemically bonded stationary phases. The immobilized phases show greater contributions from an ion-exchange mechanism than do the commercial phases. The results indicate that the silanol activity of PMOS-SiO(2) stationary phases can be adequately evaluated by using appropriate basic probes and mobile phases having different pH, using different buffers.
采用固定在硅胶上的聚甲基辛基硅氧烷（PMOS-SiO2）为固定相，评价了一些碱性溶质的色谱行为。这些测试溶质具有疏水性和亲水性。考察 pH 值的影响时，使用 80:20v/v 甲醇/缓冲流动相，pH 值范围为 5-11.5，缓冲液为硼酸盐、碳酸盐和磷酸盐等无机缓冲液，以及柠檬酸盐、三羟甲基氨基甲烷和三乙胺等有机缓冲液。在酸性流动相中，使用 50:50v/v 和 30:70v/v 甲醇/缓冲液（pH 2.5；20mmol/L）作为流动相。考察缓冲液浓度的影响时，使用 65:35v/v 甲醇/磷酸盐（pH 7；20 和 100mmol/L）作为流动相。将结果与两种化学键合固定相的结果进行了比较。固定相表现出比商业固定相更大的离子交换机制贡献。结果表明，采用适当的碱性探针和具有不同 pH 值的不同缓冲液，可以用合适的碱性探针和不同 pH 值的不同缓冲液来充分评价 PMOS-SiO2 固定相的硅醇活性。
