Packed column supercritical fluid chromatography with total column effluent introduction to flame ionization detection

Abstract

This paper presents a novel Flame Ionization Detector (FID) capable of remaining lit at the high gaseous flow rates associated with Packed Column Supercritical Fluid Chromatography (pSFC) mobile phase decompression. Using a larger burner (3.9 mm i.d. by 80 mm long) and high hydrogen flow rates this FID has a capacity of about 3 L/min total flow. Design, optimization and characterization are discussed. Neat carbon dioxide (CO2) mobile phase limits pSFC to the separation of non­polar and moderately polar analytes. An organic modifier (most commonly methanol) is often used to extend the solvating power of the mobile phase towards chromatography of more polar analytes. Formic acid responds only minimally in the FID and to date has not been explored as the primary modifier in quantities exceeding 0.5% (v/v). The effect of formic acid modifier in relatively higher concentrations on chromatographic baseline, analyte retention, selectivity and peak shape will be discussed.