Hach DR/700 Procedures Manual page 403

IODINE,
continued
Bromine, chlorine, ozone and oxidized forms of manganese and
chromium also may react and read as iodine. To compensate for the
effects of manganese (Mn
described above. Add three drops of potassium iodide, 30 g/L, to 25 mL
of sample, mix and wait one minute. Add three drops of sodium
arsenite, 5 g/L, and mix. Analyze this sample as described above. This
sample can be transferred to a 10-mL cell for measurement so the cell
cover can be closed in bright sunlight. (If chromium, is present, allow
the same reaction period with the DPD for both analyses.) Subtract the
result of this test from the original analysis to obtain the accurate iodine
result. Bromine, chlorine and iodine cannot be compensated for.
DPD Reagent Powder Pillows and AccuVac ampuls are formulated with
a buffer which will withstand high levels (1000 mg/L) of hardness
without interference.
SUMMARY OF METHOD
Iodine reacts with DPD (N, N-diethyl-p-phenylenediamine) to form a
red color which is proportional to the total iodine concentration.
REQUIRED REAGENTS (Using Powder Pillows)
Description
DPD Total Chlorine Reagent
Powder Pillows, 10 mL . . . 1 pillow . . . . 100/pkg . . . . . . . 21056-69
REQUIRED REAGENTS (Using AccuVac Ampuls)
DPD Total Chlorine Reagent
AccuVac Ampuls . . . . . . . . 1 ampul . . . . 25/pkg . . . . . . . . 25030-25
REQUIRED APPARATUS (Using Powder Pillows)
Clippers, for opening
powder pillows . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . . 968-00
DR/700 Filter Module
Number 52.01. . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . 46252-00
REQUIRED APPARATUS (Using AccuVac Ampuls)
Beaker, 50 mL . . . . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . . 500-41
DR/700 Filter Module
Number 52.01. . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . 46252-00
4+
) or chromium (Cr
Quantity
Per Test
52-77
6+
), adjust pH to 6 to 7 as
Unit Cat. No.