Rev. 007 Date 2010-01-13
CyFlow
®
space Instrument Operating Manual
14/26
Trigger
FSC, SSC, FL1, FL2, FL3 and FL4 are selected
for detection. FSC is the leading trigger
parameter.
Leading Trigger
In order to discriminate particles of interest e.g.
cells from other particles e.g. cell fragments or
nutrition particles in cell culture, a proper trigger
has to be chosen. In the CyFlow
®
space, any
parameter can be used as leading trigger.
Frequently, the forward scatter parameter (FSC)
or, preferently for smaller particles, the side
scatter parameter (SSC) is used to trigger on all
particles above a certain size range. However,
especially
for
very
small
particles,
e.g.
microorganisms, triggering on a fluorescence
parameter can be more efficient.
Selecting a parameter as leading
trigger
parameter
means: Only particles that deliver a
sufficient signal above the lower level threshold on
that parameter will be acquired. Other non-
triggering parameters are aquiring signals only for
particles that generated a valid trigger signal
(above treshhold). All other particles will not be
“recognized” by the instrument. The trigger
parameter can be used for an efficient exclusion
of unwanted particles from the analysis.
Example: Assume vertebrate leukocytes in full
blood are to be analysed. Triggering on a scatter
parameter would be difficult due to the high
number of erythrocytes in the same sample.
Staining with a DNA dye (e.g. PI) and triggering
on the DNA parameter will discriminate the
leukocytes containing a nucleus from erythrocytes
without a nucleus. This works even though there
are orders of magnitutes more erythrocytes than
leukocytes in the sample.
Trigger All
The CyFlow
®
space offers an additional method
for triggering which allows to trigger on all
parameters.
Example: Assume a part of the particles of
interest are exclusively red and another part
exclusively green fluorescing. Triggering on the
green fluorescence would exclude the red
particles from the analysis, triggering on red would
exclude the green. If the interest is in both
subpopulations, it is required to trigger on green
and red simultaneously. This can be done with
Trigger All.
Trigger parameter(s) and mode can be selected in
the instrument settings box. Refer to the software
operating manual for details.
