I recently ran several hundred propane samples on a shimadzu gas chromatograph (model 14A) over the last two weeks. Now I can't get the baseline to stay level (it drifts upwards) even after the machine has been up and running for 2+ hours.

Is this a problem with the column (i.e. cracked or needing to be cleaned)? Anyone have any good advice/tips for maintaining a standard "workhorse" GC like the 14A?

Thanks

you should try calling the tech service people for the company...that's usually what they are there for and often are pretty helpful.

thanks for the suggestion. i DID contact them but they can't help me to diagnose the problem without a service call. i was hoping that i might find someone here that had personally experienced a similar problem.

maybe no one here does GC work?

I ever experienced same problem, try this:
1. replace the column with the new one. if it give the same resut,
2. replace the septum.
hope this help

thanks kharir. i already replaced the septum so i guess i should direct my attention to the column!

Dear friend
TRY THIS FOR THE BASELINE PROBLEM
1. if the column is capillary then cut the column injector and detector end slightly with help of the knife provided.
2. clean the detector by removing it by round spanner (if you have been trained on it!). sonicate it. fit again. condition it again.
3. check the carrier gas cylider quality. Have you changed the cylinder ?

best luck
Dr. Tekale

I suggest trying an isothermal blank run (i.e. without injecting anything). If the baseline is flat then your column probably need conditioning especially if your runs normally do not require very high temperature. If you still get drift then check the carrier gas.
Regards
Daniel

Hi,
this is dhruvil.

i think u should first check for the instrument blank i.e. give a run without injectiong something in the column in the same method parameters in which u r facing the problem.

If your this run is good, i mean if the baseline is not drifting up then the problem will be with your column.
In this case u can cut the injector end column by 1 m or so and cut it slightly from the detector end as well and again try for the same analysis. If its ok then well and good. and if u r still facing the problem then check out with newer column of the same type and please repeat the same analysis. ok ?

If upon cutting the column from injector end helps u ( if the run after cutting it is somewhat better then the previous one) but not as u started with then u can cut your column further from the injector end.

ok i think this would help u...solving the problem.

bye

regards
Dhruvil