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Mass Analyser : Weak signal or no signal at all

PostPosted: Fri 20 Mar 2015 08:55
by Interchim
Weak signal or no signal at all
A weak or non-existent signal can be caused by one of 4 factors.

No signal:
1/ The source capillary is blocked
There is no outflow from the source - excess split valve pressure.
Perform source maintenance and replace the capillary (use the appropriate maintenance kit).

2/ Blocked cone
To determine whether the cone is blocked, quirt methanol onto the cone with a wash bottle. If the vacuum remains constant, the cone is blocked.
Remove the cone and sonicate it in methanol + formic acid.

3/ The molecule will not ionise by APCI, try changing the sample's pH, or the ionisation mode (ESI) instead of increasing sample concentration.

Weak signal or no signal at all:

4/ Tuning needs to be reconfigured.
Perform a calibration and tune to determine whether the ions are detected