A13914AF
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System Description
Cartridge Chemistry: Calibration Theory
Non-Linear Chemistries
Non-linear chemistries include drugs and specific protein assays. Unlike the first-order rate and
endpoint chemistries, which exhibit a linear response to increasing concentration, the calibration
curves for non-linear chemistries exhibit logarithmic (S-shaped) or other nonlinear relationships.
For this reason, curve fitting interpolation techniques are employed to construct the calibration
curve.
For some non-linear calibrations, the curve parameters for a reagent lot are calculated during
manufacturing. The curve parameters are encoded in bar code form, shipped on a card in the
reagent box and loaded onto the system. A single point calibration is then run to adjust for
instrument-to-instrument variation. If necessary, the calibration includes the sample diluent
(DIL1), used as a blank, that is subtracted from all calibrator or sample responses.
•
Multi-point chemistry calibration consists of five or six different levels of calibrators. These
chemistries set calibration based on single replicates of each calibrator level.
•
Single-point chemistry calibration consists of one or two levels of calibrators. These
chemistries set calibration based on two to four replicates of each calibrator level.
Non-Linear Calibration Formulas
The standard curve is determined by use of one of several nonlinear math models. The system uses
an iterative technique to calculate the curve parameters. A modified Newton iteration is used to
choose values. The best-fitting calibration curve is determined by minimizing the sum of the
difference between the observed response and the calculated response of each standard.
The following symbols are used in the math models presented below:
R
= sample response
Conc
= standard or sample concentration
R
0
= calculated response for a zero sample
K
c
= scale parameter
a, b, c
= parameters which define the nonlinear elements of the math model
Содержание UniCel DxC 600
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