Concentration prediction:Before testing the water sample, the nitrate nitrogen value of the water sample should be predicted, and it should be diluted and measured after exceeding the range. Example: Predicting nitrate nitrogen concentrationsThe value is 0-20mg/L, and the operation step of the 0-20mg/L range needs to be selected; To predict nitrate nitrogen concentrations above 20 mg/L, water is requiredThe sample concentration is diluted to 0-20mg/L and then measured, multiplied by the dilution factor.
Notes:[3.2mL (10+1) sulfuric acid + 0.8mL nitrate nitrogen reagent (2)], it is generally recommended to use separate amounts; If the test frequency is high,Nitrate nitrogen reagent (2) can also be diluted 5 times with (10+1) sulfuric acid for later use, and 4mL can be directly added to the test tube when used (Note:The 5-fold diluted mixture has a short shelf life, so use it as soon as possible after dilution, consult the manufacturer or sales representative for details. ）
1. When the predicted value is in the range of 0 - 20mg/L
If nitrate nitrogen is present, the water sample will appear brownish-yellow, and the darker the water sample, the higher the concentration value. Analytical Procedure: Nitrate nitrogen ; Watch out for overrange tips!
2. When the predicted value exceeds 20 mg/L
The water sample needs to be diluted to the above concentration value range, and then the operation is carried out according to the corresponding range, and the measurement result is multiplied by the dilution factor.
3. Hands-on test steps
4. Precautions
◆ If nitrate nitrogen is present, the water sample shows brownish yellow, and the darker the color, the higher the concentration value of the water sample.
◆ Pay attention to cross-contamination, use different measuring utensils for different liquids (pay attention to changing the tip when using a pipette).
◆ Use appropriate pipetting tools to take liquids, and large volume measuring tools cannot measure small volumes of water samples, such as: 20mL pipettes cannot be used to remove 2mL and belowFor liquids up to 2mL, 2 pipettes with a 1mL pipette are recommended.
◆ When using a pipette, it is necessary to calibrate the pipette frequently (it is recommended to do so once a week), and pay attention to replacing the tip during use.
