QTof MS sensitivity and resolution drop - WKB886

SYMPTOMS

• Sensitivity drops by a factor of 5 to 10
• Resolution drops significantly (e.g., 22,000 to 14,000)

ENVIRONMENT

• QTof
• SYNAPT 
• SYNAPT G2
• SYNAPT G2-S
• SYNAPT G2-Si
• Xevo QTof
• Xevo G2
• Xevo G2-S
• Xevo G2-XS

CAUSE

Supply of argon to the MS is insufficient.

FIX or WORKAROUND

Replace the argon tank.

ADDITIONAL INFORMATION

Checking the collision gas pressure on the MS vacuum gauge with the collision gas on and off will help you determine whether argon is making it into the system. There should be a large difference between the vacuum readings with the collision gas on and with the collision gas off. 

Sometimes there are stabilizers at the bottom of the argon tank, which causes a loss of sensitivity if they make it into the MS. (Try not to use the bottom of an argon tank.) Flushing the argon lines and cleaning the collision cell usually resolves this issue.