6. Operating the infinite® 200
96
Instructions for Use for
infinite® 200
No. 30017581 Rev. No. 1.4
2008-07
6.3 Optimize Fluorescence Measurements
Fluorescence measurement results may be optimized by tuning instrument
parameters on the one hand, and by selecting appropriate materials on the other
hand.
6.3.1
Instrument Parameters
Gain Settings
The
infinite
®
200
fluorescence detection system uses an analog to digital (ADC:
Analog Digital Converter) conversion of PMT signal. The gain setting controls the
amplification of the PMT when converting fluorescence light into electrical current.
The ADC needs a suitable input range of PMT current to provide a proper signal
to noise ratio (S/N) on the one hand, and linearity on the other hand. Therefore,
the gain should be tuned to make highest concentration microplate wells give
highest possible readings. Then, readings of lower concentration microplate wells
separate from background - as far as the background noise level allows for that.
Note
If any well of interest is assigned “OVER” (overflow), you may manually
reduce the gain, or select an automatic gain option (see the software
Instructions for Use).
PMT Properties
The
infinite
®
M200
and F200 may be equipped optionally with a ‘standard’ and a
‘spectrally enhanced’ PMT.
The gain for fluorescence intensity is selectable from 1 – 255. The performance
of the PMT depends on the supply voltage. The
infinite
®
200
PMTs are specified
from 300 to 1250 V. The relationship between the gain settings of the
infinite
®
200
and the voltage supply is described in Equation 6.3-1. The intended
use of the
infinite
®
200
PMT is therefore specified for gain settings from 60 to
255. Gain settings below 60 are possible and might be useful for special
applications, but the performance of the PMT is not specified for voltage supply <
300 V. Tecan therefore does not take responsibility for measurement results of
infinite
®
200
when using gain settings below 60.
Equation 6.3-1:
V
1250
*
255
Gain
U
=
