Chromatography Forum

Hi All,

I was wondering if you had a clue why all a sudden I get chromatograms with such a large solvent background (which appears after 2.3 minutes and drags forever!)

The background is basically Et2O...


Thanks!

K.

What type of instrument?
What type of injection? (split, splitless, on-column, headspace, ect)
Inlet temperature?
Column flow?

Any other information to help trouble shoot the problem will be beneficial.

GC-MS Shimadzu QP 2010.

Run -Flow control mode : linear velocity
Split
Pressure 66kPa
Total flow 81 ml/min
Column flow 1.23 ml/min
linear velocity 40 cm/s
Purge flow 6ml/min
Split ratio 60

Standard mid polar column
40°C to 280°C with 60°/min

A long tail usually means something is holding onto the solvent. Possibly contamination in the liner or inlet that adsorbs the solvent at injection then releases it slowly over time.

Also a leak at the septum can cause the actual flow to be lower than expected and lead to tailing.

If the injection port temperature is too low that can also cause such problems. Whether it is set too low or it is not heating up to the temperature it is reporting, the low temperature can cause the solvent to not evaporate quickly enough.

Does it seem to affect the target peaks or just the solvent?

Oh very good point!

I did notice that some analyste peaks did shift a bit between runs.

I will change the liner and the septum tomorrow! It’s weird because they have been changed already in June and we didn’t do a lot of injections.

Thanks again for your help! Hopefully that will solve the issue.

Kevin

Hi,

Just a big thank you! I changed the liner and the septum and that annoying solvent peak is gone!

Kevin