CPC G01N 30/60 (2013.01) [G01N 30/16 (2013.01); G01N 30/30 (2013.01); G01N 30/32 (2013.01); G01N 2030/025 (2013.01); G01N 2030/3084 (2013.01); G01N 2030/328 (2013.01)] | 5 Claims |
1. A modulation method using a comprehensive two-dimensional gas chromatograph which comprises a sample injector, a primary dimension column, a two-position three-way valve, a secondary dimension column, a three-way tube, a heating oven and a detector, comprising the following steps:
flow path connections: connecting an inlet end of the sample injector to a carrier gas line as well to a sample introduction means and an outlet end of the sample injector to a first end of the primary dimension column; connecting a second end of the primary dimension column to a first branch of the three-way tube; connecting a second branch of the three way tube to a first end of the secondary dimension column; connecting a second end of the secondary dimension column to the detector; connecting a third branch of the three-way tube to a gas inlet of the two-position three-way valve; connecting a first gas outlet of the two-position three-way valve to the carrier gas line; and connecting a second gas outlet of the two-position three-way valve to a gas-venting capillary, wherein the entireties of the primary dimension column and the secondary dimension column as well as part of the three-way tube are arranged inside the heating oven, and the two-position three-way valve is arranged outside the heating oven;
a first step of controlling the two-position three-way valve such that the gas inlet of the two-position three-way valve is in communication with the second gas outlet other than the first gas outlet for a first predetermined time trio during which the sample after primary dimension separation flows into the third branch of the three-way tube with the carrier gas;
a second step of controlling the two-position three-way valve such that the gas inlet of the two-position three-way valve is in communication with the first gas outlet other than the second gas outlet for a second predetermined time tflush during which the carrier gas comes in from the first gas outlet and carries the sample present in the third branch of the three-way tube into the secondary dimension column for orthogonal separation.
|