Chromatography Forum

Hi there,
I am new to this forum & GC. My GC-FID suffered from noisy baseline.
After changing of new FID jet & new collector assembly without improvement.
The gas-line should be Ok because it link to another same model GC-FID without problem. Any other possible cause? The model is Shimadzu GC-2010

Welcome to the forum.

That is not detector noise, it is peaks eluting from the column. What happens to the noise if you leave the oven at a constant temperature ?

Likely sources are dirt in the inlet, or contamination in the inlet end of the column. Change the inlet liner, clean out the inlet body and put in a new septum. If that does not help, cut off the first coil of the column.

Peter

Hi Peter,
Thanks for your reply.
The noise seem not affected by column temperature. Will try another column, new septum and replace liner glass wool.

After replacing of column, septum and liner glass wool, without improvement.

After replacing of column, septum and liner glass wool, without improvement.

By elimination, I think the gas chromatograph tubings and/or solenoid valves are contaminated. You may test by replace the column with a retention gap and see if the noise is still there.

Is it possible electronic noise?

This does not look like any electronic noise that I have ever seen - typically electronic noise gives very rapid pulses.

Simply replacing the galss woll is not enough - you need a new (or cleaned) liner and you need to clean out the inlet body.

What happens to the noise if you remove the column from the detector and plug the connection with a nut and a no-hole ferrule or something similar ?

Measure the air, hydrogen and make up flows to the FID using an external flow meter. Are they fluctuating.

What is the inlet temperature, column temperature and detector temperature ? What are the flow rates and pressures for the carrier gas ?

Peter

Yes, I cleaned the liner before replace glasswool.
I don't have no hole ferrule and flow meter so cannot absolutely eliminate the cause of inlet, column and fluctuation of gas flow.

You can create the no-hole ferrule from graphite ferrule. Just press the end of the ferrule hole to table so it will close, also when you overtight graphite ferrule without column it will close the hole

Thank You.
Good idea, I will try.

Thank You.
Good idea, I will try.

Be VERY careful if you do this. There is a very good chance that you will push graphite up into the FID stem, where is subsequently contaminates the tip of the column.

A better way is to find a short piece of wire (something like a paperclip maybe) about the same diameter as the column that you remove and seal that into the connection with a ferrule that fits the column.

Peter

I do not have the same GC system as you, but we see something similar on our HP 5890 if we get moisture or a bad connection in the collector. Ours is very sensitive to positioning and the cables are very touchy. You might check all of your electrical connections.