As a non-chemist, I have a couple of questions on MS analysis which may sound stupid. Please laugh and help :)

1. Does the fragmentation pattern change with the analyte concentration?
e.g. Is it possible that at lower analyte concentrations, the main fragment peak is m/z 291, while at higher concentrations, it is m/z 289?  

2. Is there any possibilities in MS that the fragment is fragmented? I know this is true in MS/MS, but I wonder if this would happen too in MS.

Thanks in advance!
--
修改:hellaround FROM 205.251.151.*
FROM 205.251.151.*