bfb tuning problems agilent 5973

[chloesabrina]

Hi, I am having problems tuning my agilent 5973, when I autotune my 50 ion relative to 95 is low, my 174 ion relative to 95 is high. Any tips as in lowering /raising values.

I have tried bfb tuning but then my 176 relative to 174 is high.

Any help is apprectiated.

[Earl]

I would try cleaning the source if that has not been done recently. Especially if some dirty samples have been run since the last good tune. If you are unsure about your source try ramping the repeller in manual tune. Consult your manual for what to look for in a dirty source.

If the source is clean check the relative abundances of 131 and 219 to 69 in your PFTBA autotune. 131 and 219 should be 35-40% (I still pass BFB when they drop to 20%) of 69. If they are higher than 40-50% that could cause what you are seeing. Try lowering these in manual tune if that is the case.

Since tuning for BFB leaves you with 176 being too high relative to 174 I automatically suspect the source needs to be cleaned. Try cleaning the souce, run the BFB tune and see if that does not fix the problem. If your in a pinch and can't shut down to clean the source, try swaping polarities and retune for BFB. That could work as a temporary solution until you get time to shutdown.

[chloesabrina]

I cleaned the source, yeah a bfb tune worked well. The source was not dirty at all(only 3 months since it had been cleaned and not much run on this instrument due to inconsistent surrogate recoveries as well as internal standards. This mass spec is extremely inconsistent with internal standards and very sensitive. If you have any suggestions ...

[AICMM]

chloesabrina,

More info please. I assume you are using purge and trap? What transfer line configuration, what MS, what flow conditions, etc....

Are you injecting BFB or purging BFB? Does your BFB area come out basically the same every day (area counts, retention times, etc...) or are you seeing differences in responsivity?

A bit early to accuse the MS if you are set up the way I think you are.

Best regards.

[chloesabrina]

Yes using purge and trap, using a pt squared so the transfer line goes from the archon to the pt2 to the concentrator (encons) then to the pt2 and then to the gc. column Flow 0.8ml/min.

we are using a 6890/5973 agilent. My internal standards will stay consistent for maybe 7 runs in a row,then suddenly bounce up (within 50 %), but enough to lower surrogate recoveries. After a couple of runs they will suddenly lower down to "normal levels". I usually direct inject my bfb at the beginning of the day, but will pull from a purged run if I run 2 clocks.

I have a huge problem with my surrogates dropping out after a week or two(dropping to about 70% recovery or lower). The problem is not with the archon isss vial, when I manually add isss to the vials I have the same inconsistency.

Let me know your thoughts.

[Earl]

What column do you use? and what are your temp ramp parameters? what trap are you using?

I have had problems with fluorobenzene area jumping 50% or more and falling again after a few runs to a few days. Made my life miserable for months.

Are the surrogate areas changing as well, or are the recoveries low/high due to internal standard areas changing?

I may have had the same problem. Let me know you column, trap and ramp parameters and I may have a solution.

[chloesabrina]

Been on vacation or would have replied sooner. Let me try to answer all the questions, I hope you have a solution for me, I am putting on all new initials calibrations on 8/13/07.

The trap is the encon 3000, my column is agilent(j+w scientific) DB-624, 25m, 0.2id, 1.12 film. My ramp temperatures are 40C hold for 3 mins the ramp 15Cper min to 205C. My run time through the column is 14 mins.

I appreciate any input.

[Earl]

Try slowing down the temp ramp when you run your next initial calibration. Go from 15C/min to 10C/min and see if that helps. Your runs will take longer (will now be 19.5 min), but the increased separation of the compounds sometimes helps with eliminating erradic responses. This is especially true for fluorobenzene.

[chloesabrina]

thanks will try that today and see what happens

[AICMM]

Chloesabrina,

Couple of other comments to add. First, regarding the tune, make sure the peak width of the 131 and 219 are under 50%. If they get too broad, that can sometimes cause problems with resolution which can cause the 174 problem. Second, why don't you add IS and surrogate from same mixture? Third, when your IS tanks, I assume everything else is failing high or no? Is your BFB area stable when you make manual injections or is it bouncing a bunch from day to day?

Finally, what is the flow rate of the column?

Best regards.