Concentration prediction:Before testing the water sample, first predict the iron concentration value of the water sample, and select the operation steps corresponding to the range, e.g. predict the iron concentration value to be 0-5mg/L, you need to select the operation step of 0-5mg/L range; If the iron concentration is predicted to be 5-50mg/L, the procedure of the 5-50mg/L range is selected.
Different types of iron are measured in the following ways:
Iron Ion Measurement:Just follow the process below to test directly.
Measurement of total iron: Take 50ml of mixed water sample into a 150ml beaker, add 1ml of (1+3) hydrochloric acid, 1ml of hydroxylamine hydrochloride solution (10%), heat and boil to volumeReduce to about 15ml to ensure that all the iron is dissolved and reduced, and then dilute to 50ml, if there is precipitation, it should be filtered and removed, the same measurement as belowSteps.
Measurement of ferrous iron:During the analysis, samples were taken according to the measurement steps (including blank samples), and 0.5ml of distilled water was used instead of iron reagent (1), 1ml of iron reagent (2) and 1ml of iron reagent (2) after sampling2.5ml of iron reagent (3) is added as usual, and the color can be measured for 5-10min.
Filterable Total Iron:Take 100ml of mixed water sample, filter the water sample with 0.45μm filter membrane, take 50ml of filtrate in a 150ml beaker for analysis, and add (1+3) hydrochloric acid1ml, hydroxylamine hydrochloride solution (10%) 1ml, heat and boil until the volume is reduced to about 15ml to ensure that all the iron is dissolved and reduced, and againDilute to 50ml, the same as the measurement procedure below.
1 1. When the predicted value is in the range of 0 0- -L 5mg/L
If iron is present, the water sample will show orange, and the darker the color, the higher the concentration value of the water sample. Analytical procedure: Iron L; Watch out for overrange tips!
2. When the predicted value is in the range of 5 5--L 50mg/L
If iron is present, the water sample will show orange, and the darker the color, the higher the concentration value of the water sample. Analytical procedure: Iron H; Watch out for overrange tips!
3. When the predicted value exceeds 5 50 0 mgL /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 iron, the water sample will show orange, 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.
