LaMotte DPD-FAS TITRIMETRIC OUT FIT DT - Manual (Page 9)

G1 =
ClO
2
5
G2 =
ClO
2
5 + K*
*where K = the “breakthrough” error
IV. DPD METHOD FOR BROMINE
Bromine may consist of free bromine or bromamines or a mixture of
these. The term “Bromine” refers to the total of free bromine and
bromamines.
A. BROMINE (IN THE ABSENCE OF CHLORINE)
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 Bromine is present, solution will turn pink.
3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution
in the buret until the pink color disappears.
NOTE:
Results obtained in mg/L (ppm) Free Chlorine. Multiply by
2.25 to convert to Bromine.
B. BROMINE (IN THE PRESENCE OF CHLORINE)
1.
Use the 1.0 mL pipet 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 *DPD #1 Powder (6807).
Mix.
3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate
Solution. This is Reading BR.
C. FREE CHLORINE
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 free chlorine is present, solution will turn pink.
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 Reagent if other forms of chlorine are to be determined.
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