LaMotte SMART Spectro Spectrophotometer - Manual (Page 94)

IODINE
Like chlorine and bromine, iodine is an effective germicidal agent employed in
drinking water treatment, pool and spa water sanitation, food service sanitation,
and other public health applications.
APPLICATION: Drinking, surface, and saline waters; swimming pool
water; domestic and industrial wastes.
RANGE: 0.00–14.00 ppm Iodine
MDL: 0.08 ppm
METHOD: In a buffered sample iodine reacts with diethyl-p-
phenylene-diamine (DPD) to produce a pink-red color in
proportion to the concentration of iodine present.
SAMPLE HANDLING &
PRESERVATION:
Iodine in aqueous solutions is not stable, and the iodine
content of samples or solutions, particularly weak
solutions, will rapidly decrease. Exposure to sunlight
or agitation will accelerate the reduction of iodine
present in such solutions. For best results start analysis
immediately after sampling. Samples to be analyzed for
iodine 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 iodine present so
that the degree of interference can be measured.
Chlorine and bromine can give a positive interference,
but these are not normally present unless they have
been added as sanitizers.
SMART Spectro Test Procedures 2.11 CHLORINE, BROMINE, IODINE
Test P
rocedures