Chlorine, Total
Chlorine, Total
ChlorineTot_PT_ULow_DPD_Eng_Ody.fm Page 5 of 8
Interferences
When the timer beeps,
introduce the contents of
the cylinder into the Pour-
Thru Cell. When the flow
stops, touch
Read.
The result in µg/L
chlorine will appear.
13. Use this value to
correct the sample result
obtained in this
procedure.
Note: See Creating a User
Program Based on a Hach
Program in the instrument
manual for details on saving a
reagent blank value.
14. Flush the Pour-Thru
Cell with at least 50 mL of
deionized water
immediately after use.
Interfering Substance Interference Levels and Treatments
Bromine, Br
2
Interferes at all levels
Chlorine Dioxide, ClO
2
Interferes at all levels
Chloramines, organic May interfere
Copper, Cu
2+
Greater than 1000 µg/L
Iodine, I
2
Interferes at all levels
Iron (Fe
3+
) Greater than 1000 µg/L
Manganese, Oxidized
(Mn
4+
, Mn
7+
) or Chromium,
Oxidized (Cr
6+
)
1. Adjust sample pH to 6–7.
2. Add 6 drops Potassium Iodide (Cat. No. 343-32) (30-g/L) to a 50-mL sample.
3. Mix and wait 3 minutes.
4. Add 6 drops Sodium Arsenite* (Cat. No. 1047-32) (5-g/L) and mix.
5. Analyze the treated sample as described in the procedure.
6. Subtract the result of 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.
Nitrite, NO
2
–
(uncommon in
clean waters)
Ozone, O
3
Interferes at all levels
Peroxides May interfere
Extreme sample pH or highly
buffered samples
Adjust to pH 6 –7. See Section 3.3 Interferences on page 41.
mg/L nitrite Apparent µg/L chlorine
2.0 mg/L 3 µg/L
5.0 mg/L 5 µg/L
10.0 mg/L 7 µg/L
15.0 mg/L 16 µg/L
20.0 mg/L 18 µg/L
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