32 | Chapter 4: Instrument Qualification
Do not remove the filter from the Test Plate, and do not use alcohol or
other cleaning agents.
¾ Verify that the Test Plate is within its calibration certification period. The
calibration sticker is affixed directly to the plate. If it is out of date,
contact BioTek to schedule a recertification.
•
Repeatability: Repeatability is a measure of the instrument’s ability to
read the same well with minimum variation between two reads with the
well in the same location.
If the reader fails this test:
¾ Check the neutral-density filters on the Test Plate to ensure there is no
debris that may have shifted between readings and caused changes.
¾ Check the microplate carrier to ensure it is clear of debris.
Linearity can also be proven by performing a regression analysis on the OD
values in a program such as Microsoft Excel, as illustrated in the following
instructions.
Analyze one wavelength at a time.
1. In Microsoft Excel, open a spreadsheet and label one column Assigned
and the next column
Observed.
2. Enter the Assigned OD data for each glass filter in the first column from
the Standards Certificate provided with the Test Plate.
3. Next, enter the Observed OD values for the same glass filters in the
adjacent column.
4. Click Tools > Data Analysis > Regression. (If the Data Analysis
command is not available on the Tools menu, you may need to install
the Analysis ToolPak in Microsoft Excel. Consult Microsoft Excel Help
for assistance.)
5. Use the Regression Input box to enter the Assigned values as the Input
Y Range
and the Observed OD as the Input X Range.
6. Click OK; the Summary Output sheet will be displayed. An R Square
value of at least 0.99 is expected and the results will often be 0.999 or
better.
BioTek
®
Instruments, Inc.
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