Sudden loss of sensitivity of API5000 in MRM mode

[yangz00g]

We have an API 5000 running trouble free in the last one and a half year since installation. Last week after routine PM, all of sudden, the sensitivity lost 90% of that before PM.

Interestingly, the sensitivity loss only ocurres to scans associated with collision cell, such as MRMs, daughter ion scan. Q1 and Q3 scan are normal, so it excludes the source or detector problem.

When looking at the PM data, I noticed the ion transmission efficiency (MS/MS), is only 30% of last PM value, just near the lowest acceptable range. I am wondering what could have happened. During the PM, only down to Q-Jet was cleaned. Anyone has some explanation or expereince? At lease let's have some fun. Enjoy and thanks!

[kerri]

The ABI's are so so nice, but can be quite mysterious when something goes wrong as the company doesn't make available a detailed instrument manual. Basically you can do some generic troubleshooting, but if that fails, you have to call the engineer back.

#1- do you see the same problem with other people's methods (running another person's method from within their project)?

#2- Have you double-checked the CAD pressure setting in your method as well as the physical connections? Is the CAD inlet valve open enough to maintain the correct pressure inside the cell? Is the cylindar in need of changing? Is the regulator set correctly?