Institute of Chemistry, Analytical Chemistry for Health and Environment, University of Graz, Universitaetsplatz 1, 8010 Graz, Austria.
Anal Chem. 2020 Jul 21;92(14):10121-10128. doi: 10.1021/acs.analchem.0c02138. Epub 2020 Jul 7.
A new class of cationic ion-interaction reagents for reversed-phase chromatography is introduced in the present work. Compounds belonging to a homologous series of linear fluoroalkyl chains including trifluoroethylamine (TFEAm), pentafluoropropylamine (PFPAm), heptafluorobutylamine (HFBAm), and nonafluoropentylamine (NFPAm) were tested and compared with ammonia and triethylamine (TEA) for the separation of selected organic acids of general interest such as the herbicides glyphosate, ethephon, and fosamine and arsenic metabolites methylarsonic acid and dimethylarsinic acid as well as other compounds. Depending on the carbon and fluorine atom number, the fluoroalkylamines were shown to be effective cationic ion-interaction reagents, significantly enhancing the retention of organic acids on a C18 reversed-phase column. Contrary to the general behavior of ion-interaction reagents (a broader term than ion-pairing reagent), significant (up to 5-fold) and consistent enhancement in the electrospray ionization mass spectrometry signal (ESI-MS) was observed relative to ammonia and triethylamine. Overall, among the tested series HFBAm was found to offer the best overall properties among the tested series as it provided a good compromise between column equilibration time (ca. 25 column volumes) and retention behavior (up to a 10-fold increase in the retention factor of acids relative to ammonia) while providing the same general advantages found for the fluoroalkylamines such as fast washout times from the ESIMS system (ca. 30 min) and a 3-5-fold signal enhancement. The fluoroalkylamines are a new class of cationic ion-interaction reagents with clear advantages over the currently employed alkylamines and may revive the general interest in ion-interaction chromatography.
本工作介绍了一类用于反相色谱的新型阳离子离子相互作用试剂。测试并比较了属于线性全氟烷基链系列的化合物，包括三氟乙胺（TFEAm）、五氟丙胺（PFPAm）、七氟丁胺（HFBAm）和九氟戊胺（NFPAm），与氨和三乙胺（TEA），用于分离具有普遍意义的几种有机酸，如除草剂草甘膦、乙烯利和福斯胺，以及砷代谢物甲基砷酸和二甲基砷酸，以及其他化合物。根据碳和氟原子的数量，全氟烷基胺被证明是有效的阳离子离子相互作用试剂，可显著增强有机酸酸在 C18 反相柱上的保留。与离子相互作用试剂（比离子对试剂更广泛的术语）的一般行为相反，与氨和三乙胺相比，观察到电喷雾电离质谱（ESI-MS）信号有显著（高达 5 倍）且一致的增强。总的来说，在所测试的系列中，HFBAm 被发现是最具整体性能的试剂，因为它在柱平衡时间（约 25 个柱体积）和保留行为（相对于氨，酸的保留因子增加了 10 倍）之间提供了良好的折衷，同时还提供了与全氟烷基胺相同的一般优势，例如从 ESIMS 系统快速冲洗时间（约 30 分钟）和 3-5 倍的信号增强。全氟烷基胺是一类新型阳离子离子相互作用试剂，与目前使用的烷基胺相比具有明显优势，可能会重新引起人们对离子相互作用色谱法的普遍兴趣。
