A GC column is an important part of compound separation when performing gas chromatography. This column resembles a coiled fine gauge wire. The interior of the column contains different materials, some nonpolar, others polar, and a mix of both. The inner material will separate compounds in different orders based on the compound's molecular structure. Changing a column can be tricky because of the delicacy of columns. Each GC will have different procedures, but the main method is basically the same for all GC column installation.
Instructions Install GC Column
1. Clean off your working surface and lay down clean, plain paper. Put on nitrile gloves before handling the column. as the oil on your hands can damage the column, which will cause problems when running samples.
2. Thread a nut and then ferrule through one end of the GC column. The nut goes on first with the threaded bit facing the end of the column. Thread on the ferrule so that the gradiated, non-flat, side goes into the nut.
3. Slide the column mounting jig into place after the ferrule. Not all machines require this mounting jig. It is used when the length of column after the ferrule needs to be quite long. Mark the column with a piece of tape so that this distance dictated by the mounting jig is maintained. If your machine does not require a mounting jig move to the next step.
4. Cut the end of the column with the provided column cutter. Do not use scissors or a knife to cut the column; use the provided cutter. This cutter is normally ceramic, or ceramic with a diamond edge. Cutting the end of the column can take many tries as the cut should not have any jagged edges. You need to score the column so that flicking the end of the column with your finger will break the column along the scored section. Inspect the end with a magnifying glass to ensure that it is smooth.
5. Wipe the newly cut column end with a piece of tissue soaked in methanol or ethanol. This will get rid of any dirt, oil or debris left on the column end. If your machine uses a mounting jig, slide it off and then wipe the end of the column.
6. Slide the nut with the ferrule inside of it on the column so that a few millimeters are extended from the nut. The actual length will depend on your GC machine. Some GC machines require only 1 to 2 millimeters to be exposed, while others require longer lengths, such as 100 millimeters.
7. Insert the column end into the injection port and screw the nut into place. Make sure the length of column exposed from the nut has not been changed. Marking the spot where the nut should be on the column with tape can help to ensure that this spot is maintained. Screw the nut into place on the injection port until it is finger tight. Use a wrench to further tighten the nut. Only a half turn past finger tight is needed.
8. Hang the column in the oven area of the GC on the provided column hangers. The column hangers are found extended from the ceiling of the oven or along the back of the oven at the top. Some machines will have slots into which the column can be inserted.
9. Repeat the same procedure with the other side of the column. Instead of inserting the second side into the injection port, this will go into the detector port.
10. Check that the nuts are tight after running the GC a few times. The heating and cooling cycles of the machine can cause the nuts and ferrules to loosen. Re-tighten these with a wrench.