Concentration prediction:
Before testing the water sample, the manganese concentration value of the water sample should be predicted, and the excess concentration should be diluted and measured, for example, the manganese concentration value should be predicted to be 0-5mg/L.You can directly follow the operation steps; If the manganese concentration is expected to exceed 5mg/L, the water sample should be diluted to the range of 0-5mg/L for determination.
Notes:
It should be determined by a φ25mm cuvette or cuvette. Cleaner water samples can be directly sampled for measurement, and strong acidic or alkaline water samples need to be adjusted to neutralAfter measurement, the water sample containing more suspended solids and organic matter should be treated as follows: take 100ml of water sample in a 250ml beaker, add 5ml of concentrated nitric acid,When heating and steaming to 10ml, if the water sample is still turbid, add 5ml of concentrated nitric acid to continue heating, if it is clearer, continue to heat, and steam until it is nearly dry and white smoke.After cooling, the residue was dissolved with a small amount of 0.2% nitric acid, then the aqueous pH was adjusted to neutral with 0.1mol/L sodium hydroxide solution, and finally diluted to with distilled water100ml (if the concentration of manganese ions in the water sample is less than 0.1mg/L, the water sample can be concentrated, for example, diluted to 20ml is 5-fold concentrated) and then measured.
1. When the predicted value is in the range of 0-5mg/L
If manganese is present, the water sample will appear pink, and the darker the color, the higher the concentration value of the water sample. Analytical Procedure: Manganese; Watch out for overrange tips!
2. When the predicted value exceeds 5mg /L
The water sample needs to be diluted to the above 0-5 mg/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 manganese, the water sample will show pink, 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.
