Supercritical Fluid Chromatography–Mass-Spectrometry of Nitrogen-Containing Compounds: Atmospheric Pressure Ionizationстатья
Информация о цитировании статьи получена из
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 29 июня 2022 г.
Аннотация:Supercritical fluid chromatography (SFC) in combination with mass spectrometry is a promising alternative to traditional chromatographic methods for the separation of polar nitrogen-containing compounds. The specificity of carbon dioxide-based mobile phases, used in this method, can affect the processes of the mass-spectrometric ionization of analytes and, as a consequence, the optimization strategy of the SFC–MS method. In this study, the effects of the composition of the CO2–methanol mobile phase, its flow rate, and also the parameters of the ion source (ESI capillary and corona discharge needle voltages, temperature) on the efficiency of ESI and APCI for a wide range of nitrogen-containing compounds from different classes were investigated. It was found that, because of the high basicity of the analytes under study, ESI in the positive ion mode is the preferred method of ionization, providing a multiple gain in efficiency compared to APCI for most analytes. An increase in the concentration of carbon dioxide in the mobile phase leads to a significant increase in the ESI efficiency and has a multidirectional effect on the ionization of analytes with different proton affinities under APCI conditions. An increase in APCI temperature leads to a decrease in the intensity of signals of protonated molecules and to the occurring of fragmentation processes regardless of the composition of the mobile phase for the vast majority of analytes.