Chromatography Forum

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)

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

CarltonPHX,

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

Best regards,

AICMM

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.

I checked the settings and nothing has changed.

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

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