no MS trace signal on LC/MS (waters ZQ)

[moonchips]

Greetings,

I run one of our drug molecules on Waters LC/MS, and did not have any MS trace signals even with UV trace of about 1.6 V signal.

moble A: 0.05% TFA
moble B: ACN
MS + mode

Please let me know possible reasons for this lost of MS signals. Is it because some molecules are extremely hard to ionize? I cleaned cone and cone gas nozzle, but still did not get MS signals.

Thanks a lot

[Uwe Neue]

Does the MS still work for other molecules?

[sassman]

So this is a triple quad instrument? What scanning mode are you using (Q1, MRM, SIM)? You should at least see some noise, especially in single MS mode (Q1 scan). What about if you inject sample directly into the MS with no HPLC separation?

[moonchips]

problem solved because of clogged capillary, so it did not work for other molecules either.

thanks everyone.