Biotek EL800, Operator'S Manual

Page: 214 / 218

188
|
Appendix E: Instructions for Programming a New Assay
BioTek Instruments, Inc.
Plot Calibration Curve
The calibration curve can be plotted either automatically or manually as
follows by plotting the anticardiolipin autoantibody concentration on the log
scale against the OD on the linear scale for each calibrator:
•
Automatic - Use appropriately validated software, and the curve fit that
best fits the data.
•
Manual - Using log/linear graph paper, draw a smooth curve through
the points (not a straight line or point to point).
Treatment of Anomalous Points
If any one point does not lie on the curve, it can be removed. If the absence
of this point means that the curve has a shape dissimilar to that of the
sample calibration curve, or more than one point appears to be anomalous,
then the assay should be repeated.
Calculation of Autoantibody Levels in Controls and Samples
Read the level of the anticardiolipin autoantibody in the controls and diluted
samples directly from the calibration curve. The control values should fall
within the range given on the QC Certificate.
Note: The standard values have been adjusted by a factor of 100 to
account for a 1:100 sample dilution. No further correction is required.
Assay Calibration
The assays are calibrated against the Louisville reference LAPL-GM-100.
One GPL unit is defined as the cardiolipin binding activity of 1 µg/ml of an
affinity purified IgG anticardiolipin preparation from a standard serum.
The Louisville reference center recommends the following positive
discrimination criteria according to the recommendation of the 2
nd
International Anticardiolipin Workshop.
Criteria Range (GPLU/ml)
High Positive > 80
Medium Positive ≥ 20-80
Low Positive ≥ 10, < 20