Total chromium reagent preparation
◆ Total chromium reagent (1): pour the whole package of powder into the beaker, then pour the whole bottle of solvent into the beaker, and pour it back into the solvent bottle for later use after it is fully dissolved.
◆ Total chromium reagent (2): dropping bottled liquid reagent. (Ready-to-use reagent)
The digester is preheated
Turn on the power of the digester, select the mode of total phosphorus or total nitrogen (125°C, 30min), press confirm (or start), and the digester will automatically heat up and preheat;Concentration prediction: Before testing the water sample, first predict the total chromium value of the water sample, and select the operation steps corresponding to the range, e.g., predict the total chromium concentration value to be 0-Between 1mg/L, you need to select the operation step of 0-1mg/L range; If the predicted concentration value is 1-5mg/L, the procedure of the 1-5mg/L range is selected.
1. When the predicted value is in the range of 0 - 1 mg/L
If total chromium is present, the water sample will appear purplish-red, and the darker the color, the higher the concentration value of the water sample. Analytical procedure: total chromium L; Watch out for overrange tips!
2. When the predicted value is in the range of 1-5mg/L
If total chromium is present, the water sample will appear purplish-red, and the darker the color, the higher the concentration value of the water sample. Analytical procedure: total chromium H; Watch out for overrange tips!
3. When the predicted value exceeds 5mgL /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 total chromium, the water sample shows purple-red, 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 a suitable pipette to take the liquid, do not use a 5mL pipette to remove 2mL and less liquid, less than or equal to 2mL of liquid, it is recommendedPipette 2 times 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.
◆ The protective cover must be covered during the heating and digestion process of the digester. During the digestion process, beware of scalding, pay attention to the high temperature area of the digester.
◆ After the digestion tube is taken out from the digester, take one piece at a time, it is forbidden to take out multiple tubes at the same time, pay attention to the high temperature, and prohibit shaking.
◆ The cooling process can be natural cooling or water cooling, but the temperature must be below 100°C to be water-cooled.
◆ The digested water sample must be completely cooled before proceeding to the next step.
◆ The digested sample tube must be clear and translucent (colored, but must not be turbid and free of suspended solids)
