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Setting Scan Parameters
CytoFluor User’s Guide
3-13
3
Excitation
Enables you to select the excitation filter for a scan. See
Section 3.3, Setting Up Multiple Scans in a Cycle, for details.
Emission
Enables you to set the emission level of the filter for a scan.
See Section 3.3, Setting Up Multiple Scans in a Cycle, for
details.
Gain
Enables you to adjust the voltage on the photomultiplier tube
in proportion to integer values from 0 to 99 for a scan. For
example, if you set the value to zero (0), the system turns off
the photomultiplier tube. If you set the value to 99, the value
on the photomultiplier tube is approximately 1080 volts (V).
The fluorescence signal level may vary from scan to scan
depending on your assay and fluorophores. You should start
scanning with a low value (for example, 40) and gradually
increase the gain until you find the optimum level(s) for your
assay. You can usually obtain optimal performance using gain
settings between 30 and 80. Typically, you use a high gain
setting for a weak fluorescence signal and a low gain setting
for a strong fluorescence signal. See Section 3.3, Setting Up
Multiple Scans in a Cycle, for details.
Auto Scale
Uses the parameters shown in the Auto Scale menu to
automatically normalize all of your data to the same
fluorescence reference. You can choose one of the internal
fluorescence reference supplied with the CytoFluor system or
use a known concentration of the fluorescent product in your
assay (control) right on the microwell plate. This option
minimizes run-to-run variations.
This field must be selected (marked with an x) for the system
to apply the settings. (See Chapter 5, Setting the Plate Layout
or Auto Scale Parameters, for details on the how to set the
Auto Scale menu parameters.) Once you select Auto Scale,
you cannot edit the Auto Scale menu parameters
(wavelengths, PMT gain, etc.).
With Auto Scale enabled, the system reads the designated
reference at the start of each cycle and calculates the scaling
factor. (CytoFluor multiplies all well readings by this factor as
acquires them.) To use the same reference for subsequent
runs, access a previously saved file and adopt the file setup.
See “Accessing a Previously Saved File” on page 3-4, for
details.
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