Cartridge Chemistry: Calibration Theory
Introduction
System Description
UniCel DxC Systems Instructions For Use A13914
Page 2-38
October 2005
Cartridge Chemistry: Calibration Theory
Introduction
Calibration determines the relationship between measured reaction responses and
known concentrations. Calibration factors are derived from this relationship. These
factors are used to convert the measured reaction responses to final concentration
results.
Calibrated chemistries include endpoint and first-order rate chemistries, drugs, DATs,
and specific proteins. Zero-order rate chemistries include enzymes, which are
precalibrated and require no routine calibration. Enzyme verification can be performed
on some of the enzymes to conform to International Federation of Clinical Chemistry
(IFCC) guidelines at 37°C.
Endpoint and First-Order Chemistries
Calibration of endpoint and first-order rate chemistries involve the use of a
single-level calibrator solution or a two level calibrator kit. Each analyte in the
calibrator solution has a known concentration value associated with it. With each new
lot of calibrator solution, the values are transferred from disk and stored in memory for
later use in the calibration procedure.
For most calibrated cartridge chemistries, the system will set calibration factors based
on four calibrator replicates per calibrator level. The instrument will determine and
discard the highest and lowest of the four replicates. The remaining two values are
called the usable calibrator replicates. All four replicates will appear on the report but
the average of the two usable replicates is used to determine the calibration factor.
For other chemistries, calibration is based on two calibrator replicates per calibrator
level. No replicates will be discarded. The average value of the calibrator replicates is
used to determine the calibration factor.
