LaMotte SMART Spectro Spectrophotometer - Manual (Page 89)

APPLICATION: Drinking, surface, and saline waters; swimming
pool water; domestic and industrial wastes.
RANGE: 0.00–4.00 ppm Chlorine
MDL: 0.02 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.
INTERFERENCE: 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-BROMINE-IODINE SMART Spectro Test Procedures 2.11
Test P
rocedures