high Ion 69 level in autotune, why?

[josh]

Hi
I have just recently started using GC-MS, Agilent 5975, with 6890. When performing the autotune with the PFTBA, I have noticed the Ion 69 abundance at levels greater than 500,000. The agilent literature gives an acceptance range of 2-400,000 abundance. The abundance was also high during qualification, but no action was taken. What is the significance of the high abundance and what should I do?

Thanks in advance
Josh

[tima]

How is the peak width??? Normally our values are below 500,000. What is the repeller voltage after it has tuned?? Give us more info on your tune values and not just the abundance of 69.

What about the 219, 414 and 502 relative abundances to the 69??

Timothy

[josh]

Mass 69 219 502
ABS 513760 356280 30221
Pw50 0.60 0.61 0.59

Water 4.3%
Nitrogen 3%

Repeller Voltage 33.81
EM volts 1294

I hope there is a clue here somewhere!

Josh

[AICMM]

josh,

Your peak width's are too wide. Should be between about 0.52 to 0.45. Use AMU gain and offset to get these below 0.52. That will drop the abundance of the 69 as well as the 219 and 502.

Best regards.

[josh]

Thanks for the advise, much appreciated.
I'll give it a go!