Hach DR/700 Procedures Manual page 367

CADMIUM,
13.
Press:
ZERO
The display will
count down to 0.
Then the display will
show 0 mg/L and the
zero and S1 prompts
will turn off.
SAMPLING AND STORAGE
Collect samples in an acid-cleaned glass or plastic container. Adjust the
pH to 2 or less with nitric acid (about 2 mL per liter). Store preserved
samples up to six months at room temperature. Before analysis, adjust
the pH to 2.5 with 5.0 N sodium hydroxide. Correct the test result for
volume additions; see Sampling and Storage, Volume Additions
(Section I) for more information.
DITHIVER SOLUTION PREPARATION AND STORAGE
Store DithiVer powder pillows away from light and heat. A convenient
way to prepare DithiVer solution is to add the contents of 16 DithiVer
Metals Reagent Powder Pillows to a 500-mL bottle of chloroform and
invert several times until well mixed (carrier powder may not dissolve).
Store dithizone solution in an amber glass bottle. This solution is stable
for 24 hours for cadmium testing. Do not use it to run lead tests.
continued
14.
Place the
prepared sample in
the cell holder.
Note: Typical indoor
lighting permits the
DR/700 to operate with
the cell compartment
open. In bright
sunlight, it may be
necessary to close the
cell compartment cover.
Transfer 10 mL of the
blank and 10 mL of the
sample to 10-mL sample
cells and proceed.
52-41
15.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
µg/L cadmium (Cd).
Note: For best results, a
reagent blank should be
determined for each
new lot of DithiVer
Metals Reagent Powder
Pillows. Use
demineralized water in
place of the sample in
Step 4 and subtract this
amount from the test
results obtained in Step
15.