PDF(Pubmed)
Abstract：
In this study, water was used as an additive in the methanol-modified carbon dioxide-based eluent for the elution of some basic organic compounds from a hybrid silica column via supercritical fluid chromatography (SFC). The experiments were applied to sulfonamides, propranolol, and other organic nitrogen compounds involving aromatic rings from different classes of amine, pyrimidine, and purine with different pKa values (the pKa values for the studied analytes range from 4.6 to 10.4). The results revealed different responses to the different percentages of water addition. Adding 1~2% of water to the modifier (methanol) led to a positive effect manifested by more symmetrical peak shapes and reduced retention times for most compounds. The key factor for this improvement in the properties of chromatographic peaks is due to the adsorption of water on the silanol groups of the stationary phase, consequently resembling the phenomena observed in hydrophilic interaction liquid chromatography (HILIC). Moreover, the availability of hydrogen bond acceptor and donor sites in the analyte structure is an important factor to be considered when adding water as an additive to the modifier for improving the chromatographic peaks. However, introducing water in an amount higher than 3% resulted in perturbed chromatographic signals. It was also found that water as an additive alone could not successfully elute propranolol from the hybrid silica column with an acceptable peak shape; thus, the addition of a strong base such as amine salts was also necessary. The proposed use of a particular amount of water in the mobile phase could have a positive effect compared to the same mobile phase without water, improving the chromatographic peak properties of the elution of some basic organic compounds from the hybrid silica column.
摘要：
在这项研究中,水被用作甲醇改性的二氧化碳基洗脱液中的添加剂，用于通过超临界流体色谱（SFC）从混合硅胶柱中洗脱一些碱性有机化合物。实验应用于磺胺类药物，普萘洛尔,和其他有机氮化合物，涉及来自不同类别的胺的芳环，嘧啶,和具有不同pKa值的嘌呤（所研究分析物的pKa值范围为4.6至10.4）。结果揭示了对不同的水添加百分比的不同响应。向改性剂（甲醇）中添加1〜2％的水可产生积极作用，表现为大多数化合物的峰形状更对称，保留时间减少。色谱峰性能改善的关键因素是由于水在固定相的硅烷醇基团上的吸附，因此，类似于在亲水相互作用液相色谱（HILIC）中观察到的现象。此外，分析物结构中氢键受体和供体位点的可用性是当将水作为添加剂添加到改性剂中以改善色谱峰时需要考虑的重要因素。然而,以高于3%的量引入水导致干扰的色谱信号。还发现，单独作为添加剂的水不能成功地从混合二氧化硅柱中洗脱出具有可接受的峰形的普萘洛尔；因此，也需要加入强碱如胺盐。与不含水的相同流动相相比，建议在流动相中使用特定量的水可能具有积极作用。改善了杂化硅胶柱洗脱某些碱性有机化合物的色谱峰性质。
