In this video, we will calibrate the EXO fluorescent dissolved organic matter, or fDOM sensor in RFU. You can also use the EXO Handheld or the Kor Mobile App.
We want to make sure we have our personal protective equipment on. I have my gloves and safety glasses, since we are working with quinine sulfate in acid.
We are starting with our fDOM sensor installed and a clean calibration cup and probe guard. You’ll want to make sure the central wiper and any copper tape is removed from the sonde, as these can degrade the standard solution. And I’ll go ahead and install the sensor port plug, and we’ll tighten it down with the sensor tool.
We will perform a 2-point calibration for this sensor. For the first point, you can use distilled or DI water for zero. Make sure to fill the cal cup up to the first line from the bottom with DI water. Once the sensor is submerged, I like to give it a few taps to make sure there are no bubbles on the sensor surface.
In Kor, click calibrate for fDOM in RFU. Kor Software will indicate if readings are stable in real time on this graph. Once the readings stabilize, you’ll notice the line is flat, we’ll click apply and proceed to the next standard. Click to add another cal point.
Remove the sonde from the standard and dry off the sensor guard and the sensor. For calibration point two, we’ve prepared a quinine sulfate standard solution with a concentration of 300 ug/L. Please check out our video on mixing the quinine sulfate solution for information on standard preparation.
Immerse the sensor in the standard solution and give it a tap to clear any bubbles.
Wait for readings to stabilize before applying the calibration. Once readings are stable, click apply.
Now you will see the calibration summary screen where you can choose to redo the calibration or complete the cal. I’ll choose to complete the calibration.
The last thing is to rinse off the quinine sulfate solution from the sonde. You want to make sure to properly dispose of the quinine sulfate solution.
Our EXO fDOM sensor is now calibrated! Please check out our other EXO U calibration videos, and thank you for watching.