Chromatography Forum

Hello everyone,
I have a problem with the GC-FID Agilent 6890N;
when I run the blank I don't see the baseline, what I see is a lot of background noise under zero.

I need your help please.
Tell me what I can do to correct this problem.

Best regards,

The background noise is the baseline. Presumably you do not see any peaks ? How much do you know about running and troubleshooting the instrument ? Have you done on troubleshooting on this problem ? What were the results ?

Peter

Thank you Peter for your help. I appreciate it.
For the problem of the baseline I have edit parameters for signal plot and run my sample again and I found linear baseline without peak.
After that I run the ethanol 40% and I found the same baseline without peak.

I decide to change the FID but unfortunatly the results are the same.

You have no peaks, even for standards? Do you have flow out the end of your column? Or does it have 4 ends instead of 2? Is your flame OK? Has this system worked properly before or is this something new?

Yesterday I checked if the carrier gas pased at the end of the column and it was passing.
The flamme is ok and this is a new problem.

I use packed column.

Can you explain me please about those ends? 4 and 2.

Thank you.

Check that you do not have the ZERO turned on for your signal. If you by mistake zeroed your signal when it was very high, you will not see any peaks until they go above the the zero value.

Regarding Steve's comment about 4 column ends. He assumed that you were working with capillary columns, and it is not unusual for the column to break in the middle, hence the column with 4 ends. You are using packed columns, so you will not see that problem.

Gasman

There are lots of reasons why you might not see a signal from the detector. So you need to troubleshoot systmatically, step by step ?

First; do you have the correct detector channel selected in the software, and are all the other settings correct ?

If you select detector signal on the front panel of the GC and do an injection do you see the value in the readout changing ?. If not what value do you see ?

If you light the flame and hold a cold, shiny surface (say a shiny spanner) at the detector outlet, do you see condensation.

If you touch the detector body with the spanner do you see the detector signal or the chromatogram trace change ?

If you inject the gas from a cigarette lighter do you see a peak ?

Peter

There are lots of reasons why you might not see a signal from the detector. So you need to troubleshoot systmatically, step by step ?

First; do you have the correct detector channel selected in the software, and are all the other settings correct ?

If you select detector signal on the front panel of the GC and do an injection do you see the value in the readout changing ?. If not what value do you see ?

If you light the flame and hold a cold, shiny surface (say a shiny spanner) at the detector outlet, do you see condensation.

If you touch the detector body with the spanner do you see the detector signal or the chromatogram trace change ?

If you inject the gas from a cigarette lighter do you see a peak ?

Peter

Dear Peter,

I am working with the person who wanted your help.
We have even changed the detectors and check them so we are now sure that the detector
is working well because I have seen the condensation. Let me see if I can see if the chromatogram
can change when I am injecting the gas from a cigarette lighter. I was thinking that I have a problem with the column. I have to check the packed column.

Regards,

WICLEF KAGISHA

Hi Wiclef

Condensation shows only that the flame is burning. There are lots of other things that can be wrong.

Peter

What is the signal on GC display? Do you use column compensation?