Subcritical water chromatography with flame ionization detection

A chromatographic method has been developed that allows subcritical (hot/liquid) water to be used as a mobile phase for packed-column reverse-phase LC with solute detection by name ionization detection, Detection limits (S/N > 3:1 for butanol) of 1 ng were achieved with water flows of 20 and 50 mu L/min and 5 ng with flows ranging from 100 to 200 mu L/min. Quantitative determinations of ethanol in alcoholic beverages are in excellent agreement with label values and replicate injections have RSDs of similar to 2%. Increasing the column temperature lowers the dielectric constant (polarity) of water, decreases the elution time, and improves the peak shape for compounds ranging from alcohols to hydroxy-substituted benzenes to amino acids. Temperature programming up to 175 degrees C can be used to improve separations and decrease analysis times.