While trying to test out a new method (taken from the literature, nothing crazy for GCMS) The GC starts preping for the run and goes through the usual equilibration stage for pre-set amount of time. Everything is in green, counter runs down and GC enters Pre-run stage where the split is being ramped up and down, the used ratio is 10:1, so during the pre-run its continuosly changed from 0-10/12. After going from 0-10:1 the split tanks to 0 which casues the carrier gas pressure to drop significantly and GC becomes 'not ready' and the whole process starts again. Anyone has any idea why this is the case? Method equilibrates fine and GC is fine while idle. The issue starts when I try to inject. Thank you for any suggestions or comments. I am attaching video of the issue.
Have you worked before with such low carrier gas pressure (1.3 psi)? I have an older PerkinElmer GCMS device (Autosysem XL/TurboMass Gold) and its pneumatic system becomes unstable at pressure values significantly below 20 kPa (~3 psi). Try to increase the carrier gas pressure.
Although the previous statements from Nikolay A. Mironov and Noel W Davies can be the answer - have you tested their advice? - I will add the chance of septum leaking after several injections. This sudden pressure drop is very common when your septum has had so many perforations that it starts allowing the gas to vent. If this is the problem, you just change the septum for a new one.
That's probably the case: the input of the carrier gas pressure. You must be aware the data system is prepared to "receive and accept" the pressure unit either in atm. (atmospheres), bar (= 1,013 atm.) or psi. 1 atm. is 14,7 psi. Do the calculation and enter the value being certain the accurate unit is put in like requested. This "old" instruments were shipped to European laboratories and prepared to accept all kinds of pressure units. Forget SI systems! The US and the UK still work with their "own" units. The rest of the world is modern!!!
Hi Jana, Were you ever able to resolve this issue with the split flow? I am having the exact same issue, only difference is I am using Programed Flow at 1.3 ml/min which translates to about 6psi. My sequence start cycle is EXACTLY the same as yours. PE doesn't seem to be aware of the issue and thinks it's part of the dotlink setup, but not sure. Thoughts?
- Badges
- Science topic
- Similar topics
- Analytical Chemistry
- Column