Abbott Diagnostics Aeroset - CALIBRATION THEORY

Calibration Theory
AEROSET
®
Customer Training Guide 6-5
94858-103 — July 2003
CALIBRATION THEORY
Calibration can be described as analyzing samples of known
concentrations, recording the absorbance value(s) calculated for each
sample, and plotting the measured absorbance values versus the known
concentration to create a graph for evaluating unknown sample
absorbances. To understand how the AEROSET System calculates the
measured absorbance values used for calibration and to understand how
the System calculates patient results, it is important to know the different
assay types and the different methods of measuring and calculating the
absorbance values.
Assay Types
Two different photometric reaction types are measured on the AEROSET
System.
• End-point - The reaction reaches an equilibrium and at that time
there is little or no further change in the absorbance readings. The
absorbance readings used for calibration and the absorbance
readings used to calculate results are measured during this
equilibrium time.
• Rate
- There is a constant change in absorbance over time. Readings
are performed several times during this reaction, and the absorbance
change over time (activity) is calculated and used for calibration and
to calculate results.
In addition, at each read point the AEROSET System can measure at one
(monochromatic) or two (bichromatic) wavelengths. Most AEROSET
System assays are bichromatic. The following table explains how the
absorbance is calculated for each of these types:
Number of Wavelengths
Measured at Each Read Point
How the Absorbance Values are
Calculated
1 - Monochromatic The reading from only the single
wavelength is used.
2 - Bichromatic The reading taken at the secondary
wavelength is subtracted from the
reading taken at the primary wavelength
and the difference is used as the
absorbance value.
• Displayed absorbance data are
converted to readings for a 10mm
light path length.