Concentration prediction:
Before testing the water sample, the nickel concentration value of the water sample should be predicted, and the concentration should be diluted and measured, for example, the nickel concentration value should be 0-4mg/L.You can directly follow the operation steps; If the nickel concentration is expected to exceed 4mg/L, the water sample should be diluted to the range of 0-4mg/L for determination.
Notes:
Cleaner water samples can be directly sampled for determination, such as high suspended solids and total nickel measurement, the following treatment is required: take 50ml of sample in a beaker, add0.5ml concentrated nitric acid, heat and evaporate until nearly dry, after cooling, add 0.5ml of concentrated nitric acid and 0.5ml of perchloric acid to continue heating and evaporate until nearly dry. After cooling, use 1% nitrateThe acid dissolves and if the solution is still not clear, repeat until the solution is clear. Then use 2mol/L sodium hydroxide to adjust the solution to neutral, and dissolve the solutionTransfer to a 50 ml volumetric flask and rinse the beaker with a small amount of water, dilute to the scale, for assay.
1 1. When the predicted value is in the range of 0-4mg/L
If nickel is present, the water sample will appear yellowish-brown, and the darker the color, the higher the concentration value of the water sample. Analytical Procedure: Nickel; Watch out for overrange tips!
2. When the predicted value exceeds 4mg /L
The water sample needs to be diluted to the above 0-4mg/L concentration value, 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 there is nickel, the water sample shows yellow-brown, 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 range measuring tools cannot measure small volumes of water samples, such as: 5mL pipettes cannot be used to remove 2mL and below liquidsFor liquids less than or equal to 2mL, it is recommended to pipette twice with a 1mL pipette.
◆ 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.
