Gas chromatograph

A gas chromatograph comprising:

• a sample gas generator configured to generate a sample gas from an injected sample;
• a separation column fluidly connected to an outlet of the sample gas generator, the separation column being configured to separate components in the sample gas generated by the sample gas generator;
• a detector fluidly connected to an outlet of the separation column, the detector being configured to detect the components separated in the separation column;
• a plurality of gas supply sources each configured to supply a carrier gas for carrying the sample gas generated by the sample gas generator to the separation column;
• a switching unit fluidly connected to the plurality of gas supply sources, the switching unit being configured to switch such that one of the plurality of gas supply sources is fluidly connected to the sample gas generator;
• a regulator interposed between the switching unit and the sample gas generator, the regulator being configured to regulate a gas supply pressure from the gas supply source and a gas supply flow rate to the sample gas generator;
• and
• an out-of-gas determination unit configured to determine whether or not out of gas has occurred in the gas supply source supplying the carrier gas to the sample gas generator, based on the gas supply pressure or the gas supply flow rate,
• wherein after the out-of-gas determination unit has determined that the out of gas has occurred in the gas supply source supplying the carrier gas to the sample gas generator, it is configured to perform a column protection operation for changing the gas supply source fluidly connected to the sample gas generator by the switching unit.