Why would my pressure drop during bfb injection?

[CarltonPHX]

I did injector maintainance on a HP series 6890. Replaced septa, liner, and gold seal then my bfb abundance dropped from 1,200,000 to 120,000. I have been working for about a week now trying to figure what might have caused this but to no avail. I have changed the column, cleaned the source, replaced the filaments, checked the electron multiplier. The only thing I notice is that after shooting the bfb, as soon as I press start, the front inlet pressure drops from 26.0 to 22.0 then back up to 27.0 before stabilizing. Could this be the problem? If so, then what could be a possible solution? (oh i've also checked the flows and they all seem normal)

[Peter Apps]

As soon as you have an exact 10 x difference in results the first thing to eliminate is a change in the data processing settings. Nevertheless your numbers are suspiciously rounded, so I suspect that you are providing us with approximations. Some real numbers would be helpful.

A pressure fluctuation just after injection can indeed be the cause of the problem. I suspect that it is going from standby to run as you press the start - there should be an option to go from standby into pre-run or whatever they call it.

Peter

[AICMM]

CarltonPHX,

BFB by liquid injection or via purge and trap? Also, splitless or split?

Best regards,

AICMM

[CarltonPHX]

Peter,
Thanks for the reply, I will check the data processing settings and let you know if anything has changed. Also, you are correct, the numbers that I provided for the pressure fluctuations are rounded because they are not consistent.


AICMM,
Thank you for your reply. It is a liquid injection/splitless.

[CarltonPHX]

I checked the settings and nothing has changed.

[CarltonPHX]

I replaced the chem trap, and replaced the liner and still no change..

[Peter Apps]

When you checked the flows which flows did you check (split, septum purge, column ?) and how did you measure them ?

What happens if you press start and then inject ?

Peter