Hach DR/850 Procedures Manual page 83

BROMINE,
continued
Interferences
Summary of Method
Interfering Substance
Acidity
Alkalinity
Chlorine
Chlorine Dioxide
Chloramines, organic
Hardness
Iodine
Manganese, Oxidized
4+ 7+
(Mn , Mn )
or
Chromium , Oxidized
6+
(Cr )
Monochloramine
Ozone
Peroxides
Extreme sample pH and
highly buffered samples
Bromine reacts with DPD (N,N-diethyl-p-phenylenediamine) to
form a magenta color which is proportional to the total bromine
concentration.
Interference Level and Treatment
Greater than 150 mg/L CaCO
color or color may fade instantly. Neutralize to pH 6-7
with 1 N sodium hydroxide. Determine amount to be
added on separate sample aliquot, then add the same
amount to the sample being tested. Correct for volume
addition (See Section 1, Correcting for Volume
Additions).
Greater than 250 mg/L CaCO
color or color may fade instantly. Neutralize to pH 6-7
with 1 N sulfuric acid. Determine amount to be added on
separate sample aliquot, then add the same amount to the
sample being tested. Correct for volume addition (See
Section 1, Correcting for Volume Additions).
Interferes at all levels
Interferes at all levels
May interfere
No effect at less than 1,000 mg/L as CaCO
Interferes at all levels
1. Adjust sample pH to 6-7.
2. Add 3 drops potassium iodide (30 g/L) to a
25-mL sample.
3. Mix and wait 1 minute.
4. Add 3 drops sodium arsenite (5 g/L) and mix.
5. Analyze 10 mL of the treated sample as described in the
procedure.
6. Subtract the result from this test from the original
analysis to obtain the correct bromine concentration.
Interferes at all levels
Interferes at all levels
May interfere
Adjust to pH 6-7. See Interferences, Section 1.
83
. May not develop full
3
. May not develop full
3
3