Abstract: A solute focusing method is applied to the on-column injection of a liquid sample in gas chromatography so that relatively large sample sizes can be used without causing intolerable column flooding. The injection zone of the column is kept originally at a temperature below the solvent boiling point but the temperature in the adjacent downstream zone is kept higher than the solvent boiling point so that the solvent will evaporate and flow downstream, leaving the solute molecules concentrated within a relatively limited length along the column.

Abstract: An unheated septumless on-column injector with two internal flow paths is provided. A syringe means is positioned adjacent and communicates in vapor-tight relationship with the inlet ends of the two internal flow paths. The first internal flow path accepts and guides a needle from said syringe means onto the column of a gas chromatograph to permit injection onto the column. The second internal flow path allows the syringe means to either be loaded from or purged into an attached, sealed container. The needle of the syringe means is movable between the first and second paths by external manipulation. In particular embodiments, carrier gas is provided to sweep the sample into the low diameter column and cooling means is provided to ensure that the point of injection of the liquid onto the chromatographic column is maintained at a temperature below the boiling point of the most volatile component of the liquid sample.