In this video, we will calibrate the EXO Rhodamine sensor in µg/L using Kor Software. You can also use the EXO Handheld or the Kor Mobile app.
We are starting with our rhodamine sensor installed, as well as a conductivity/temperature sensor since the Rhodamine sensor is temperature-dependent. As a best practice, make sure all the sensors, probe guards, calibration cups, and wipers are clean. It may be helpful to have a dedicated probe guard and cal cup just for calibration. This is a four-point calibration. The rhodamine sensor has 2 LEDs, and we will do two calibration points for each LED. We will be using prepared standard solutions of Rhodamine dye for this calibration at 25 and 125 µg/L. Please check out our video on mixing the Rhodamine dye solution for information on standard preparation.
The first calibration point is zero, and you can use distilled or Deionized water. Fill the cal cup to the first line from the bottom with DI water. Then immerse the sonde. I like to give it a few taps to make sure there are no air bubbles on the sensor face. If you have a clean wiper, you can run the wiper to clear any air bubbles on the sensor lens.
In Kor, we will select Rhodamine to calibrate. Kor Software will indicate if readings are stable in real time on this graph. It should show 0 for the first standard value. We’ll run the wiper now. Once the readings stabilize, click apply and proceed to the next calibration point. Click to add another cal point.
Remove the sonde from the standard, and dry off the sensor guard and the sensors. For the second calibration point, we are using our prepared Rhodamine dye standard solution with a concentration of 25 µ/L.
Immerse the sensors in the standard solution and give it a tap to clear bubbles. If you are using a clean wiper, you can run it again in the software.
Double-check that Kor recognizes the standard value of 25 µg/l. Wait for readings to stabilize before applying the calibration. Once readings are stable, click apply. As we move on to calibration point 3, keep the sensors submerged in the same 25 µg/L standards. Click to add another cal point.
Double-check that the values in Kor read 25, and again, we will wait for the readings to stabilize. Then we will apply the calibration. Click to add another cal point. The fourth calibration point should be between 125 and 1000 µg/L. Use the standard concentration that is most representative of your expected data. Today we are using 125 µg/l. Please refer to our Rhodamine solution prep video to see how to prepare this solution.
We will rinse with DI water and dry the sensors and sensor guard. Now we’ll fill immerse the sonde in the fourth standard and give it a quick tap. Make sure Kor recognizes the standard value as 125 µg/L. You can run your wiper again now. We will wait for the readings to stabilize, then complete the calibration. Note that you can redo a cal point at any step in this process. Now you will see the calibration summary screen where you can complete the calibration.
Our EXO Rhodamine sensor is now calibrated! Please check out our other EXO University calibration videos, and thank you for watching.