jiayb141
第3楼2012/04/12
Time delayed fragmentation (TDF) is particularly interesting
for spectra interpretation because it reduces multiple
sequential fragmentations and so leads to simpler tandem
mass spectra.27 CID is the consequence of the conversion
of translational energy of the precursor ion, generated by
its collision with a neutral gas, into internal energy. If the
internal energy is high, multiple generation fragments will
be observed. Once a precursor ion has been activated, the
time window can be defined to allow ion relaxation. It is
a three-step process including ion activation, ion relaxation
and fragment collection. Ion relaxation occurs via fragmentation
and cooling with residual gas. In contrast to the classical
triple quadrupole, ion activation occurs via q2-to-Q3 acceleration
rather than via Q1-to-q2 acceleration. Hence the
product ion spectrum originates from a precursor ion which
has a modified internal energy based on a time delay. This
is achieved by first collecting the precursor ions in the trap,
while fragment ions outside a given mass range are not
trapped. After a cooling period, typically in the range of
milliseconds, the trap is adjusted such that it can trap the
fragments originating from the cooled precursor ion (Q3 fill
mass). TDF can be applied to determine the origin of secondary
fragment ions by changing the Q3 fill mass.
netsking
第4楼2012/04/13
你这27 CID是什么意思呢? 你自己做过吗? 能否介绍一下经验吗?
speakout
第5楼2012/04/14
英文不行,看不懂,网上搜了一下中文截图版解释。