Abstract: In a gas chromatographic system that includes a column and an injector with a chamber, a carrier gas normally flows into the chamber at a constant rate, and a constant primary pressure is maintained at the column inlet. A sampling receptacle selectively communicates a sample vessel with a source of transfer gas or the chamber. The vessel is pressurized with the transfer gas to a starting pressure greater than the primary pressure. Analyte sample in transfer gas is then tranferred from the vessel to the chamber by the vessel pressure while the vessel pressure remains greater than the primary pressure. Carrier gas flow is discontinued during transfer, so that analyte sample transfers through the chamber into the column by the primary pressure linearly with time. Standby and venting states are provided.

Abstract: A gas chromatographic system includes a column and an injector for delivering into the column a test portion of flow. The injector has an exit passage for discharging a split portion of carrier flow. A flow controller for regulating the inlet flow rate includes a variable outlet restrictor for the split portion, a flow rate detector disposed to detect inlet flow rate, and a feedback flow controller to regulate the outlet restrictor to maintain the inlet flow rate substantially constant. Pressure at the inlet to the injector is regulated by detecting pressure at an outlet and providing feedback control to an inlet restrictor. An integral module for the gas components is used on each side of the injector. Calibration and correction for gas characteristics are provided in the feedback for a chromatographic system and for other flow controller regulation.

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.