Hach DR2400 - Page 192

Chlorine, Total
Chlorine, Total
Page 2 of 4
ChlorineTot_MP_High_DPD_Eng_2400.fm
Interferences
5. Remove the cell from
the adapter and add the
contents of one DPD
Total Chlorine powder
pillow to the sample. Cap
and shake the cell about
20 seconds to dissolve.
6. Touch the timer icon.
Touch
OK.
A 3-minute reaction
period will begin.
7. After the color has
developed fully, wipe the
cell and place it into the
adapter.
8. Touch Read.
Results will appear in
mg/L Cl
2
.
Interfering Substance Interference Levels and Treatments
Acidity
Greater than 150 mg/L CaCO
3
. May not develop full color or color may fade instantly. Neutralize
to pH 6–7 with1 N Sodium Hydroxide (Cat. No. 1045-32). 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 3.1.3 Correcting for Volume Additions).
Alkalinity
Greater than 250 mg/L CaCO
3
. May not develop full color or color may fade instantly. Neutralize
to pH 6–7 with 1 N Sulfuric Acid (Cat. No. 1270-32). 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 3.1.3 Correcting for Volume Additions).
Bromine, Br
2
Interferes at all levels
Chlorine Dioxide, ClO
2
Interferes at all levels
Chloramines, organic May interfere
Iodine, I
2
Interferes at all levels
Manganese, oxidized
(Mn
4+
, Mn
7+
) or Chromium,
oxidized (Cr
6+
)
1. Adjust sample pH to 6 –7.
2. Add 2 drops Potassium Iodide (30 g/L) (Cat. No. 343-32) to a 5-mL sample.
3. Mix and wait 1 minute.
4. Add 2 drops Sodium Arsenite* (5 g/L) (Cat. No. 1047-32) and mix.
5. Analyze the treated sample as described in the procedure.
6. Subtract the result from this test from the original analysis to obtain the correct
chlorine concentration.
* Samples treated with sodium arsenite for manganese or chromium interferences will be hazardous wastes as regulated by the
Federal RCRA for arsenic (D004). See Section 4 for more information on proper disposal of these materials.
Ozone Interferes at all levels
Peroxides May interfere
Extreme sample pH or
Highly buffered samples
Adjust to pH 6–7 using acid (Sulfuric Acid, 1.000 N, Cat. No. 1270-32) or base (Sodium
Hydroxide, 1.00 N, Cat. No. 1045-32).
Read