Concentration prediction:
Before testing the water sample, first predict the copper concentration value of the water sample, and select the operation steps corresponding to the range, for example: predict the copper concentration value to be 0-5mg/L, you need to select the operation step of 0-5mg/L range; If the copper concentration is predicted to be 5-50mg/L, the procedure of the 5-50mg/L range is selected.
Notes:
Cleaner water samples can be directly sampled for determination, and water samples containing more suspended solids and organic matter should be measured as follows: 50ml should be pipettedWater samples are put in a 150ml beaker, 5ml of concentrated nitric acid is added, heated and evaporated to about 10ml, 5ml of concentrated nitric acid and 1ml of perchloric acid are added to the slightly cooled beaker, and the heating continuesEvaporate to nearly dry, add 40ml of water, heat and boil for 3min, cool, adjust the pH of the test solution to neutral with (1+1) ammonia, transfer to a 50ml volumetric flask for steamingDistilled water is diluted to the reticle.
1 1. When the predicted value is in the range of 0-5mg/L
If copper is present, the water sample will show a purple color, and the darker the color, the higher the copper concentration value. Analytical Procedure: Copper L; Watch out for overrange tips!
2. When the predicted value is in the range of 5-50mg/L
If copper is present, the water sample will show a purple color, and the darker the color, the higher the copper concentration value. Analytical Procedure: Copper H; Watch out for overrange tips!
3. When the predicted value exceeds 50mg /L
The water sample needs to be diluted to the corresponding concentration value in sections 1-2 above, and then operated according to the corresponding range, and the determination result is multiplied by the dilution factor.
4. Test steps on the computer
5. Precautions
◆ If there is copper, the water sample shows purple, and the darker the color, the higher the concentration value of copper.
◆ 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.
