LaMotte DPD-FAS TITRIMETRIC OUT FIT DT - Manual (Page 7)

C. FREE CHLORINE
1.
Use the 0.5 g spoon to add 0.5 g of *DPD #1 Powder (6807) to a
third 100 mL sample. Mix.
2. Use the 0.5 g spoon to add 0.25 g of *EDTA Disodium Salt (6382).
Mix.
NOTE:
In the presence of high monochloramine, add 10 drops of
*Steadifac Reagent (6383WT) to prevent interference. This will
give a Free Chlorine reading only. Discard and start again at Step
1A and continue to Step B5 for monochloramine, etc. Do not add
*Steadifac if other forms of chlorine are to be determined.
3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate
Solution. This is Reading A. DO NOT DISCARD SOLUTION.
Solution will be used for Combined Chlorine test.
D. MONOCHLORAMINE
4.
Use the 1.0 g spoon (0697) to add one small *Potassium Iodide
Crystal (6809) to the sample from Step 3. Swirl to mix. If
monochloramine is present, solution will turn pink.
NOTE:
If dichloramine concentration is expected to be high,
substitute 2 drops Potassium Iodide, 0.5% (6810) for one *Potassium
Iodide Crystal in Step 4.
5. Continue titrating with the diluted Ferrous Ammonium Sulfate
Solution until the pink color disappears. Record buret reading as
Reading B.
(Reading B – Reading A), mL = (ppm) Monochloramine
Retain sample and buret for testing Dichloramine.
E. COMBINED CHLORINE
6.
Use the 1.0 g spoon (0697) to add 1 g of *Potassium Iodide Crystals
(6809) to the solution from the Free Chlorine test above. Mix to
dissolve crystals. Wait 2 minutes.
7. Add 10 drops of *Steadifac Reagent (6383WT). Mix.
8. Titrate rapidly with the diluted Ferrous Ammonium Sulfate
Solution. This is Reading C. DO NOT DISCARD SOLUTION.
Solution will be used for Total Chlorine Including Chlorite test.
F. TOTAL CHLORINE INCLUDING CHLORITE
1.
Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807)
to a clean 250 mL Erlenmeyer flask (0433).
2. Use the 1.0 g spoon (0697) to add 1.0 g of *Potassium Iodide
Crystals (6809) to the flask (0433).
7