I am working on Perkinelmer GC-FID Clarus 400 N2 as carrier and H2 plus air for FID. Kindly Suggest me the possible problem and solution to the problem
Both regulator, sensor and other accessory functions of GC are not working, please consult with any service providing engineer.
Hi Murtaza!
Without having more information there is no sense in guessing where the problem is.
What colomn are you using (length, diameter)?
What is you reading of the pressure gauge for N2?
Have you checked the flow rates of H2 and air?
Is a makeup gas involved?
Regards
Stefan
Dear Stefan
Thank you very much
Column dimensions are 30m x 0.25mmx0.25um
The pressure gauge reading towards GC from cylinder is above 6 (unit not sure) i guess it is psi will check it when close to instrument
H2 and Air flow rate never checked and do not know how to check that
N2 is carrier as well as Makeup gas
Best regards
Hi Murtaza,
6 PSI (if unit is really PSI, usually at gas cylinders unit is bar) will be too low to get more then 1ml/l carrier gas flow. I would assume you need something around 20-30PSI carrier gas pressure at injector. At most GC´s there is second flow/pressure regulator for the carrier gas, maybe this turned of / too low. Check the manual :-)
As for the FID: in short: turn of H2, make up gas and air as well as FID heating. Use a bubble meter at FID, turn on air and set to a flow rate of 200-300ml/min (check the GC manual for more exact numbers). Turn of air, and open H2, set H2 to something between 20-30ml/min (again check FID manual). Open air flow, turn on FID heating and check whether FID ignites. Typically a FID needs an air/H2 ratio of 10:1. If detector is on, slowly increase make up gas to around 20ml/min.
But, since you don´t seem to have own hands-on experience to even check the different flow rates you better ask for help from a colleague. :-)
Stefan
Dear colleague, perhaps bottle of N2 and other bottles are empty, you should replace them. Regards, ISliwka
As Stefan and Ireneusz suggest, turn off the detector heaters and gases. When no longer hot, carefully fit a rubber tube onto the GLASS flame tip, then CAREFULLY attach your bubblemeter. You can improvise a bubble meter from any kind of plastic tube and soapy water. There must be adequate flow of all gases as noted above to work.
Hi. I agree with the above opinions. First the detailed characteristics of the system used should be given and a substantial recheck is required to address the problem. I guess the main problem is related to the status of bubblemeter.
Just to add to what other colleagues suggested. That is if you checked and all gas flows are OK. Probably you need to clean the FID jet. For if its blocked or dirty the flow rates of the other gases do drop as the make up comes on. One needs a steady flow for the FID flame to ignite.
Yusuf
Hi Murtaza, I agree with Abdullahi, check the flows and clean the FID jet. I had the same problem a few months ago and once the jet was cleaned up the GC worked perfectly.
Dear all
Thank you very much. The problem is resolved finally. But now when i inject n hexane or acetone I get no peak. Then i tried to play a little with method there was a parameter called range. it has two options 1 and 20. when I select 20 it just show straight baseline with n-hexane as well as with acetone. But when i try 1 it shows a big heap at 5 minutes to 10 minutes but no proper peak.
The column i am using is Methyl 10 % phenyl 25 MX 0.32mm 0.1 um. and carrier gas is N2 at a flow of 2 ml/min I also tried 4 ml/min but result was same. I am using FID He flow 45 ml/Min while air about 450 ml/Min. Injector temperature is 150 and detector temp 220 C
The problem is not resolved yet. What are the flows measured at the flame tip, with the flame out, of course?
The Problem is resolved dear David
the H2 flow is about 45 while Air is 450 ml /min approximately as measured by bubble flow meter. Now I can have the proper N2 flow control. Actually the problem was due to improper connection of N2 gas at the back of GC. Now flame is easily lit. but the results of acetone or n-hexane are not in form of proper peak. it just gives a large hump and no sharp peak of solvent
If you place a small mirror, or cool, smooth spatula over the flame tip, does it always show fog (water vapor), when operating after injecting a small sample of 2 microliters? The small cap on top of the detector over the flame should allow observation of this water vapor while running. A large sample can blow out the flame: the flame must then be relit with its push button.
Inject a hexane sample containing a small amount of a higher boiling point chemical, such as nonane or decane or both. When your GC is operating properly, about 2 minutes and 3 minutes after the solvent is eluted, the nonane then decane should show as separate peaks. IF this is not happening, something else is wrong. Also I think 450 ml/min of air is too much: that is half a liter per minute blowing out of the tiny flame tip and "cooling" it too much. The flame detector is hot on purpose.
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