Quality control of GC gas flow

A gas chromatography (GC) apparatus comprising:

• a sample collection loop, precut column loop including a precut column, a main column, a carrier gas inlet, and a reverse flow gas inlet in fluid communication with a multiport valve, the main column configured to separate light hydrocarbon compounds in a gas stream, the precut column configured to remove heavier hydrocarbon compounds from the gas stream;
• a GC detector in fluid communication with the main column;
• and
• an electronic controller configured to:
• open the carrier gas inlet;
• set the multiport valve to a first position with the carrier gas inlet open, the first position providing fluid communication between the carrier gas inlet, the sample collection loop, the precut column loop, the main column, and the detector;
• make a first detector measurement when the multiport valve is set in the first position;
• set the multiport valve to a second position with the carrier gas inlet open, the second position providing fluid communication between the carrier gas inlet, the main column, and the detector such that carrier gas bypasses the sample collection loop and the precut column loop;
• make a second detector measurement when the multiport valve is set in the second position;
• and
• compare the first detector measurement to the second detector measurement to check the sample collection loop, the precut column loop, and the multiport valve for leaks.

A method for quality control checking a gas chromatography (GC) apparatus, the method comprising:

• providing a GC apparatus including at least a main column, a sample collection loop, a precut column loop including a precut column, and a detector in fluid communication with a multiport valve, the main column configured to separate light hydrocarbon compounds in a gas stream, the precut column configured to remove heavier hydrocarbon compounds from the gas stream;
• opening a carrier gas inlet and a precut column loop backflush inlet;
• setting the multiport valve to a first position with the carrier gas inlet open and the precut column loop backflush inlet open, the first position providing fluid communication between the carrier gas inlet, the sample collection loop, the precut column loop, the main column, and the detector;
• making a first detector measurement when the multiport valve is set in the first position;
• setting the multiport valve to a second position with the carrier gas inlet open and the precut column loop backflush inlet open, the second position providing fluid communication between the carrier gas inlet, the main column, and the detector such that carrier gas bypasses the sample collection loop and the precut column loop;
• making a second detector measurement when the multiport valve is set in the second position;
• and
• comparing the first detector measurement to the second detector measurement to check the sample collection loop, the precut column loop, and the multiport valve for leaks.