LaMotte DPD-FAS TITRIMETRIC OUT FIT DT - Manual (Page 11)

A. IODINE
1.
Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807)
to the 250 mL Erlenmeyer flask (0433).
2. Fill the 100 mL graduated cylinder (0419) to the 100 mL line with
sample water. Pour into Erlenmeyer flask. Swirl until powder is
dissolved. If Iodine is present, solution will turn pink.
3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution
in the buret until the pink color disappears.
4. Multiply result by 3.6 to obtain mg/L (ppm) Iodine.
VI.DPD METHOD FOR OZONE
A. OZONE (IN THE ABSENCE OF CHLORINE COMPOUNDS)
1.
Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807)
to the 250 mL Erlenmeyer flask (0433).
2. Fill the 100 mL graduated cylinder (0419) to the 100 mL line with
sample water. Pour into Erlenmeyer flask. Swirl until powder is
dissolved. If ozone is present, solution will turn pink.
3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution
in the buret until the pink color disappears.
4. Multiply result by 0.676 to obtain (ppm) Ozone.
B. OZONE (IN THE PRESENCE OF CHLORINE COMPOUNDS)
1.
Use the 1.0 mL pipet (0354) to add 2 mL of Glycine Solution
(6811) to a 100 mL sample. Mix.
2. Use the 0.5 g spoon (0698) to add 0.5 g of *Potassium Iodide
Crystals (6809).
3. Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807).
Mix.
4. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution
in the buret until the pink color disappears. Result is Total Chlorine
only.
Result Ozone – Result Total Chlorine = Ozone
NOTE: A procedure to determine the amounts of free and combined
chlorine would require a further test in which *DPD #1 Powder is added
to a 100 mL sample and titrated to give free chlorine plus a proportion
of ozone. After adding approximately 0.5 g of Potassium Iodide Crystals
and titrating again, the result would give total chlorine plus the same
proportion of ozone. Titrate the developed colors immediately at each
stage. The difference between these readings give combined chlorine.
This result enables the total chlorine figure as previously obtained to be
subdivided into Free and Combined Chlorine.
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