By Anonymous on Sunday, February 23, 2003 - 11:10 pm:
Dear All,
We have a problem with our Quadrupole Mass Spectrometer and I hope you can give me some advise as to how we should go about solving the problem.
When we first acquired our system, the system can easily be calibrated from a range of 50-2000 m/z (positive and negative mode) using ms/ms with good results. However, it is almost 2 years now since we bought it, we noticed a gradual decline in the efficiency of the machine. The resolution for positive mode calibration for m/z>1400 is no longer acceptable and it was even worse for the negative mode.
What can we do to improve the results of our mass calibration again? Apart from the CEM, are there any parameters that we can adjust/change to improve the outcome? Are there any part of the Mass Spectrometer that we need to replace to achieve good results in case change of system parameters do not produce any significant improvement?
I thank you all in advance for any help/advice that you can give us.
FE
By Anonymous on Monday, February 24, 2003 - 03:10 am:
In my experience with a single quadrupole LC-MS system (Agilent 1100+1946A) the performance of spectrometer autotune is better after cleaning procedures of interface (ESI), capillary, and skimmers.
Those procedures are instrument-specific and generally provided by manufacturers.
Contamination (not macroscopic) of capillary and skimmers occurs even when the instrument is operated with purified samples and low concentration (<5mM) of mobile phase modifiers.
I hope this note will be useful for you.
By Anonymous on Tuesday, February 25, 2003 - 06:24 pm:
Thank you for your advice. However, I have already done the cleaning of the entrance especially at the first quad. But the sensitivity only improved a little. I'm sorry for not mentioning this in my earlier message. Our system is a Tandem Mass Spectrometer. Is there anything else that I can do to get better results?
Thanks!