tecan sunrise - Instrument Linearity with Liquid Samples

TECAN
7. Quality Control
2006-03 Instructions for Use for sunrise Absorbance Reader No. 30008746 Rev. No. 1.4 7-9
7.3.5 Instrument Linearity with Liquid Samples
The linearity for the instrument and application at the wavelength used can be
checked by using a dilution series of a solution.
The result depends on the purity of the dye used and the meniscus of the liquid in
the wells.
As a reference, dilution series of Methyl Orange in 0.1 % Tween 20 solution for
measurements at 492 nm can be used.
The dilution series should be within the range of 0.1 to 3.0 OD for a standard or
6-filter instrument and within the range of 0.1 to 2.5 OD for a tuneable wavelength
instrument.
For other wavelengths, different solutions must be used.
250 ml of each dilution are then pipetted into the microplate, a minimum of at
least two samples should be used for each dilution to reduce the errors caused
by pipetting.
Make sure that the instrument is using the accuracy measurement mode.
The microplate is then measured and a linear regression of OD against
concentration is drawn from the average of the measured OD values.
Determine the unweighted residual square value R
2
of the regression line.
Typical residual square values for a standard application are equal or better than
R
2
= 0.998.
Note
Data can vary due to pipetting inaccuracy, meniscus of the liquid and the
application used.
Note
The limits of the instrument’s linearity will be measured with the QC plate.
Example for a tuneable wavelength instrument
Readings 0.100 to 2.500 OD
Dilution Factor Absorbance
1 2.621 OD
0.5 1.323 OD
0.25 0.679 OD
0.125 0.360 OD
0.0625 0.192 OD
0.03125 0.110 OD
0 0.025 OD
Equation for linear regression: y = 2.5888x + 0.0314
Residual squared value: R
2
= 1