How to use the COD controller to calibrate the COD sensor?

COD is the amount of oxidant consumed when a certain strong oxidant is used to treat water samples under certain conditions. It reflects the degree of material pollution in the water. The greater the chemical oxygen demand, the more serious the pollution by organic matter in the water. COD is expressed in mg/L, and the COD value can be monitored through water quality monitoring instruments. The online COD Sensor COD351 developed and produced by Daruifuno adopts the principle of ultraviolet absorption method. By measuring the absorption degree of ultraviolet light of 254nm wavelength by organic matter, it can accurately measure the content of dissolved organic pollutants in water. The COD sensor needs to be calibrated before use. Using our matching DUC2-COD online controller can easily and quickly calibrate the COD sensor. Next, we will explain the calibration process of the COD sensor in detail.

Preparation of calibration standards
1. Accurately weigh 1.2754g of KHP into a 1000mL flask. Dilute to the highest volume with distilled or deionized water and shake well to obtain a 1500mg/L concentration COD standard solution;
2. Take 100mL of the 1500mg/L COD standard solution prepared in step 1, inject it into a 1000mL range flask, then use distilled or deionized water to adjust the volume to the highest mark, shake well, and you will get a concentration of 150mg/L. COD standard solution.
3. Other concentration standard solutions can be calculated and configured according to the dilution method.

Notice
It is best to prepare the standard solution for immediate use to ensure accuracy.
High-concentration mother liquor can be sealed and filled and then placed in the refrigerator for subsequent dilution; the shelf life is recommended to be no more than one month.

Connect the COD sensor model COD351 to the controller. After powering on, place the COD sensor in pure water.
1. Identify the standard solution
Place the COD sensors in the standard solutions we prepared. Two standard solutions of 600mg/L and 1200mg/L are prepared here. Read the value to determine whether the label of the standard solution is correct.

2.Restore calibration
Long press the menu key to enter the main menu, select [sensor set]-[COD CAl]-[reset COD CAl] to restore calibration to prevent previous data interference.

3. Start calibration
Note that the sensor calibration should be in order from low to high. Take out the COD sensor from the pure water and place it in the 600mg/L standard solution. In the [sensor set]-[COD Cal] menu, we support one or two-point calibration. Select [1nd Point Cal] and enter the value 600. Press the enter key to start the calibration. When the progress bar reaches 100%, the calibration is completed;

Similarly, perform [2nd Point Cal], enter 1200, and press the enter key to start the calibration. When the progress bar reaches 100%, the calibration is completed; in this way, the two-point calibration finished.

4. Backtesting
In order to verify the accuracy of the data, we can conduct a backtest again. If the values are not much different, it means the calibration is successful.

The above is about Daruifuno's online COD Controller and COD sensor calibration methods. If you are interested in our products, please contact us.