Design and Optimization of a Corona Discharge Ion Source for Supercritical Fluid Chromatography Time-of-Flight Mass...

The interfacing of capillary column supercritical fluid chromatography (SFC) to time-of-flight mass spectrometry (TOFMS) through atmospheric pressure chemical ionization (APCI) was investigated. An ion source chamber and a new, flexible, and efficient transfer line from the SFC to the TOFMS system were designed to accommodate the requirements of this study. Ionization of analytes was performed using a corona discharge needle. The interface was equipped with two multiple-axis translation stages for positioning of the transfer line tip and the discharge needle inside the ion chamber. The investigations were oriented toward the optimization of parameters which have a strong effect on the intensity and stability of the analyte signal, including background stability, corona discharge needle positioning in the ion source, transfer line tip and discharge needle relative positioning, curtain gas and makeup gas flow interactions, ion chamber temperature, and elution pressure of analytes from the SFC system.