Hach DR/700 Procedures Manual page 370

CADMIUM,
continued
c) Extract the solution with several 2 or 3 mL portions of pure
chloroform to remove any remaining DithiVer, again discarding the
bottom layer each time.
d) Continue with Step 7.
e) In Step 8, substitute 28.5 mL of DithiVer solution for the 30 mL.
f) Continue with Step 9.
Highly buffered samples or extreme sample pH may exceed the
buffering capacity of the reagents and require sample pretreatment; see
Interferences, pH (Section I).
WASTE DISPOSAL
Dispose of cyanide-containing wastes following the steps below:
a) Use good ventilation or a fume hood.
b) Add the waste while stirring to a beaker containing a strong solution
of sodium hydroxide and calcium hypochlorite or sodium hypochloride
(household bleach).
c) Maintain a strong excess of hydroxide and hypochlorite. Let the
solution stand for 24 hours.
d) Flush the solution down the drain with a large excess of water.
SUMMARY OF METHOD
The dithizone method is designed for the determination of cadmium in
water and wastewater. The DithiVer metals reagent is a stable powder
form of dithizone. Cadmium ions in basic solution react with dithizone
to form a pink to red cadmium-dithizonate complex, which is extracted
with chloroform.
REQUIRED REAGENTS
Cat No.
Cadmium Reagent Set (68 Tests) . . . . . . . . . . . . . . . . . . . . . . . . 22422-00
Includes: (1) 14202-99, (1) 14458-17, (4) 12616-68,
(1) 767-14, (4) 2180-49
52-44