摘要:
A gas chromatography system having a column comprising a precolumn and an analytical and also having a source of backflush pressure applied at the intersection of the precolumn and the analytical column. The split column arrangement enables the backflushing of high boiling point components while enabling the simultaneous analysis of lower boiling point components located in the analytical column upon the application of backflush pressure. This greatly reduces the cycle time of a chromatography system as it is unnecessary to backflush the much more slowly eluting, high boiling point components through the entire length of column and there is no need to delay backflushing until completion of analysis of the components of interest. In this manner, backflushing occurs simultaneously with analysis for a first reduction of cycle time, and the high boiling point components are backflushed through a reduced length of column for a second reduction of cycle time of the chromatography system. A thermal focusing chamber enables the trapping of the sample at the sample tube end closest to the precolumn enabling a much more concentrated sample which yields much broader peaks in the chromatogram.
摘要:
Several embodiments of gas chromatography systems are disclosed incorporating mechanical sample injection valves. The injection valves incorporate a delivery tube (126) having an outlet which is swept past the inlet of separation columns (128,130,132) to provide a short duration inlet plug into the separation columns. Carrier gas and sample gas flow is managed through valves to prevent inadvertent injection after an injection is desired and to assure that the sample is not contaminated by past sample flow. Embodiments of injections valve are described for providing inputs into several gas chromatography columns. In addition, a gas chromatography system is described in which multiple columns are used which are time multiplexed with a single detector to produce a complex combined chromatogram from the plural columns. By appropriate selection of column characteristics and injection sequence, the resulting chromatogram can provide an overlay of chromatograms which provide good resolution of all the constituents of the mixture of interest within a short analysis time.
摘要:
A gas chromatograph system (10) including a cold trap (12) having two portions (12a and 12b), a capillary tube (14) and a porous layer open tubular (PLOT) column (15), for substantially simultaneously trapping lower and higher boiling point gasses. The capillary tube (14) enables cold trapping of lower boiling point gasses while the PLOT column (15) enables cold trapping of higher boiling point gasses. The capillary tube interconnects at one end to an analytical column (20) and a sample gas source (26) and interconnects at its other end to a first end of the PLOT column (15). The other end of the PLOT column interconnects to a carrier gas source and a vacuum source. The capillary tube and PLOT column are both positioned within a temperature controlled environment of the cold trap. During the collection mode, the temperature control means maintains a relatively low temperature to condense the sample components. During injection of the sample from the cold trap to the analytical column, the temperature control means maintains a relatively high temperature to vaporize the sample components.
摘要:
A gas chromatograph system (10) including a cold trap (12) having two portions (12a and 12b), a capillary tube (14) and a porous layer open tubular (PLOT) column (15), for substantially simultaneously trapping lower and higher boiling point gasses. The capillary tube (14) enables cold trapping of lower boiling point gasses while the PLOT column (15) enables cold trapping of higher boiling point gasses. The capillary tube interconnects at one end to an analytical column (20) and a sample gas source (26) and interconnects at its other end to a first end of the PLOT column (15). The other end of the PLOT column interconnects to a carrier gas source and a vacuum source. The capillary tube and PLOT column are both positioned within a temperature controlled environment of the cold trap. During the collection mode, the temperature control means maintains a relatively low temperature to condense the sample components. During injection of the sample from the cold trap to the analytical column, the temperature control means maintains a relatively high temperature to vaporize the sample components.