Separations of Some Alcohols, Phenols, and Caboxylic Acids by Coupling of Subcritical Water Chromatography and Flame Ionization Detection with Postcolumn Splitting

A coupling system of subcritical water chromatography and flame ionization detection (SubWC-FID) with precolumn preheating and postcolumn splitting mode has been established. Separations of some alcohols, phenols, and carboxylic acids have been performed on a Polymerx RP-1 (PS-DVB) column with the column temperature ranging from 160°C to 210°C by using the SubWC-FID system and pure water as the mobile phase. The stable working conditions of FID have been optimized and the effects of column temperature, flow rate of the mobile phase and splitting ratio on sample separations have been examined. The results indicate that the FID system with postcolumn splitting is stable even at flow-rate of mobile phase as high as 1.48 ml min−1. The linear dynamic ranges are between two and three orders of magnitude and the limits of detection of ethanol, phenol, and acetic acid at a splitting ratio of 1:20 are 17 ng, 54 ng and 68 ng, respectively.