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2.7 Crosstalk correction
2.7 Crosstalk correction
2.7.1 Introduction
Crosstalk is a situation in which light pulses from adjacent samples interfere with the pulses of
the sample under measurement. This may occur in the case of microtitration plates in which you
cannot use the cassettes 1450-101 or 1450-102. This is because designs of cassette other than the
1450-101 or 1450-102 have part of the optical shielding between the wells removed to
accommodate the microtitration plate.
Crosstalk can be corrected with the MicroBeta program. Before counting the actual samples, the
amount and type of crosstalk is defined using special standardization or normalization samples,
with the type of solution as similar to the actual samples as possible. The normalization or
standardization is done first and the calculated crosstalk factors are then used when counting the
actual samples. A CPM normalization run is needed for crosstalk corrected CPM results and a
DPM standardization run is needed for crosstalk corrected DPM results.
2.7.2 Crosstalk CPM normalization
2.7.2.1 Preparation of normalization samples on a 96 or 384-well microtitration
plate
Take sample solution with some activity (+ scintillant) which corresponds to the samples to be
analyzed, i.e. has the same isotope and solvent, and pipette the same volume as in the samples,
into well G11 (96-well plate) or well N22 (384-well, 1-6 detectors) or well M21 (384-well, 12
detectors).
For a 96-well plate with a 1-6 detector counter, pipette background solution (corresponding to the
sample solution, but without activity) into wells A1, F11 and G10 (96-well), where the latter two
are the crosstalk samples. G10 is only needed for strip plates and A1 if background correction
has been selected. With a 12 detector counter use positions A1 and F11. Strip plate is not
available. For a 384-well plate with a 1-6 detector counter use positions A1, M22 and N21 for
strip plate. With a 12 detector counter use positions A1 and M22. Strip plate is not available.
The sample array for a 96-well plate with a 1-6 detector counter is as follows, where S1 is the
sample solution and B1, C1 and C2 are the background solutions:
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