Column switching–back flushing technique for the analysis of aromatic compounds in gasoline

A simple method, based on the technique of capillary column switching–back flushing, has been developed for the detailed analysis of aromatic compounds in gasoline. The sample was first separated on a 30-m long OV-2330 polar precolumn and then backflushed onto a nonpolar analytical column. The early eluting components from the precolumn and the components of interest (aromatic compounds plus heavier compounds) eluting from the analytical column are all directed to the same flame ionization detection system through a T piece, which permits the quantitative analysis of aromatic hydrocarbons in gasoline by a normalization method using correcting factors. The switching time window of the method is ±5 s, resulting in easier operation and higher reliability. The reproducibility of the quantitative analysis was ≤3% RSD for real gasoline samples.