IDS IDS-iSYS, User Manual

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1-5-4- Biochemistry assays
Samples and reagents are aspirated in accordance with the validated parameters for each assay and are
transferred into a cuvette where the changes in absorbancy (or optical density) will be monitored in the course
of the reaction taking place.
Depending on the type of assay defined in the analytical configuration for each set-up, the following
absorbancy measurements are used in the calculations:
•
Terminal Point
Uses the last absorbancy.
•
Delta Terminal Point
Calculation of the di ff erence between the first and the last absorbances.
•
Kinetic
Calculation of the slope by linear regression over the absorbancies measured
Calculation of enzymatic activities using the formula:
Activity =
VT x
∆
DO/mn x 1000
VE x l x ε
Where:
•
V
T
= Total volume.
•
V
E
= Sample volume.
•
l = Optical pathway (1 cm).
•
ε = Molar extinction coe ffi cient of analyte (in L.mol -1 .cm -1 ).
Comment: In the set-up, the factor entered is equal to ε x 100
The results are calculated either in relation to a calibration, or multiplied by a factor.
The function used for the calibration is fixed in the analytical configuration. The functions available are:
•
Linear regression.
•
Linear interpolation.
•
Polynomial function degree 2.
•
Polynomial function degree 3.
•
Polynomial function degree 4.
•
Cubic Spline.
The calibrations and controls can be programmed on demand or automatically managed in terms of frequency
by the analyser.
A request for calibration is automatically accompanied by a request to perform QC control.
Requests for calibrations and controls can be made at any time. If the analyser is in the process of carrying
out the assay, the calibrations and controls take place prior to the analyses requested on the samples.
Operating principle
1-5- Operating principles (continued)
IDS-iSYS User Manual - Revision M1
Operating principle 1-5
14
Software version V 14