CALIBRATION AND NORMALIZATION
PerkinElmer Life and Analytical Sciences 121
Chapter 7
Calibration and Normalization
Before any samples are counted, you should calibrate and normalize the system
(S
elf Normalization and Calibration - SNC) and assess the performance of the
instrument (I
nstrument Performance Assessment - IPA) The SNC/IPA protocol
requires a special protocol flag and cassette loading that depends on your
instrument model.
Calibration/Normalization
During the calibration and normalization portion of the SNC, the voltage applied to
each of the two Photomultiplier Tubes (PMTs) is adjusted until the tubes have
been synchronized in their response to a Carbon-14 standard. Then, the high
voltage to both PMTs is adjusted simultaneously until the endpoint of the 14C
spectrum falls at the appropriate position in the Spectralyzer (on-board 4000
channel) multi-channel analyzer. This process is designed to ensure that the
instrument accurately quantifies the energy from all beta-particle emissions.
IPA
During Instrument Performance Assessment (IPA), the instrument measures
background, counting efficiency, sensitivity (Figure-of-Merit) and the
reproducibility of sample counting (Chi-Square test). Note: IPA is an optional
feature on the 2800 and 2900 series instruments.
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