LaMotte SMART Spectro Spectrophotometer - Manual (Page 105)

(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
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-TOTAL, UDV SMART Spectro Test Procedures 2.11
Test P
rocedures