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exactmeters.com
COMBINED CHLORINE
eXact
®
Strip Micro CL (DPD-1, DPD-3, DPD-4) Interferences
Interfering
Substance
Interfering Levels & Treatments
Acidity
If sample has acidity above 150mg/L CaCO3 test may not develop
full color. Neutralize to pH 6.0 to 7.0 with 0.5N Sodium hydroxide.
Alkalinity
If sample has alkalinity above 200mg/L CaCO3 test may not
develop full color. Neutralize to pH 6.0 to 7.0 with 0.5N Sulfuric
acid.
Bromine & Bromamines,
Br
2
Color similar to other oxidizer reaction at all levels.
Chlorine, Cl
2
Color similar to other oxidizer reaction at all levels.
Chlorine Dioxide, ClO
2
Color similar to other oxidizer reaction at all levels.
Copper, Cu
+2
Color development is reduced above 10 ppm (mg/L).
Iodine, I
2
Color similar to other oxidizer reaction at all levels.
Manganese, Oxidized
(Mn
+4
, Mn
+6
) or
Chromium,
Oxidized (Cr
+6
)
See AWWA procedure 4500-CL F, 1(d) for removal of
interferences.
Monochloramines (NH
2
Cl)
(applies to DPD-1 only)
Monochloramine interferences are known to occur in free chlorine
DPD methods. This interference is dependent on temperature and
monochloramine concentration.
Ozone, O
3
Color similar to other oxidizer reaction at all levels.
Peroxides
Interference is possible.
pH
Typical pH samples of potable water with a pH of 6.0 to 9.0 are
OK. If outside this range adjust to pH 6.0 to 7.0 using acid (0.5N
Sulfuric acid) or base (0.5N Sodium hydroxide).
FILL, DIP, READ
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CAP CELL AND READ RESULTS
Place the Cell Cover onto the CELL and
READ
result displayed as Combined Chlorine. This result is
automatically stored in the CL(3) menu. After testing is
complete, rinse the sample cell immediately and clean
with brush.
DPD will stain the CELL wall if allowed to remain in the CELL. To remove staining, rinse
cell thoroughly and
fi
ll with water then add two (2) drops of bleach (5-8%) and clean with
brush until stain is removed. Caution: Avoid contact of bleach with eyes and clothing.
To get
fi
nal result as Total Chlorine, press
READ
again.
Note
: If second DPD-1 strip was used for Free
Chlorine >6ppm then Total Chlorine will have to
be manually calculated.
