Test Procedures
The fact that chlorine can be easily detected and measured makes chlorine a favorite
water sanitizer of those concerned with the public safety of water supplies. Chlorine
concentrations in the range of 0.1 to 0.4 parts per million are usually maintained in
municipal supplies.
Chlorine can be added in the form of chlorine gas, liquid sodium hypochlorite (bleach),
granular calcium hypochlorite or as organic chlorine compounds. Chlorine is not present
in natural water supplies; if it is present it is the result of chlorination of a water supply
or of chlorinated compounds being discharged as waste from industrial operations. The
presence of chlorine in concentrations above 0.5 parts per million should be considered
evidence of pollution from chlorine treated effl
uents or from a process in which high
concentrations of chlorine are used.
APPLICATION:
Drinking, surface, and saline waters; domestic and industrial
wastes.
RANGE:
0.00–10.00 ppm Chlorine
MDL:
0.10 ppm
METHOD:
In the absence of iodide, free available chlorine reacts instantly
with DPD to produce a red color. Subsequent addition of
potassium iodide evokes a rapid color response from the
combined forms of chlorine (chloramines).
SAMPLE HANDLING &
PRESERVATION:
Chlorine in aqueous solutions is not stable, and the chlorine
content of samples or solutions, particularly weak solutions,
will rapidly decrease. Exposure to sunlight or agitation will
accelerate the reduction of chlorine present in such solutions.
For best results, start analysis immediately after sampling.
Samples to be analyzed for chlorine cannot be preserved or
stored.
INTERFERENCES:
The only interfering substance likely to be encountered in
water is oxidized manganese. The extent of this interference
can be determined by treating a sample with sodium
arsenite to destroy the chlorine present so that the degree of
interference can be measured.
Iodine and bromine can give a positive interference, but these
are not normally present unless they have been added as
sanitizers.
CHLORINE-FREE
, UDV
SMART Spectro 2 Test Procedures 05.02.16
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