Eppendorf TCA-3 Temperature Monitoring System - Manual (Page 45)

Calibration instructions
TCA-3 Temperature Monitoring System
English (EN)
45
Carrying on with the above example, 26.25 * 0.96 = 25.20 °C and 25.00 – 25.20 = -0.20 °C and similarly
76.25 * 0.96 = 73.20 and 73.00 – 73.20 = -0.20 °C so the offset is still -0.20 °C. If there are two different
answers (allowing for rounding errors) then please check your calculations.
6.3.1 Using Excel for calculation
By using excel to do the calculation a multi point (two or more) calibration can be achieved using linear
regression (least squares linear regression).
• As above take the calibration reading and the TCA-3 monitoring system readings, and then using linear
regression (least squares linear regression) on a computer is the best to find the Offset and Gain values.
• Using Excel, enter two columns of figures with the calibration values in the left hand column and the
TCA-3 monitoring system values in the right hand column. Next highlight two cells where the result is to
appear and use the array function LINEST to calculate the least squares result.
• These values need to be entered into the Eppendorf web service for that probe.
This is done by clicking on the Preferences Icon for that probe. In the Sensor Preferences window
click on the Advanced Tab. Enter the Offset value into the Calibration Offset box and the gain value into
the Calibration Gain box
The example figures can be seen in the Sensor Preferences window below.
If the other sensors need calibrating on the TCA-3 monitoring system they are done in the same way.
The LINEST function is an array function, press CTRL+SHIFT+ENTER to run the function. The
function will produce two results. An example is shown below.
Calibration A2-05
values values
25.00 26.25
55.00 57.50
73.00 76.25
gain offset
0.96 -0.20