Hach DR/700 Procedures Manual page 410

LEAD,
continued
16.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
µg/L lead (Pb).
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 2 and subtract this
amount from the test
results obtained in Step
16.
DITHIVER SOLUTION PREPARATION, STORAGE AND
REAGENT BLANK
Store DithiVer Powder Pillows away from light and heat. A convenient
way to prepare this solution is to add the contents of 10 DithiVer Metals
Reagent Powder Pillows to a 500-mL bottle of chloroform and invert
several times until well mixed. Some of the powder will not dissolve.
Store DithiVer solution in an amber glass bottle. This solution is usable
for 24 hours for running lead tests. Do not use it to run cadmium tests.
SAMPLING AND STORAGE
Collect samples in acid-cleaned glass or plastic containers. Adjust the
pH to 2 or less with nitric acid (about 2 mL per liter). Preserved samples
can be stored up to six months at room temperature. Adjust the pH to
2.5 to 4.5 with 5.0 N sodium hydroxide before analysis. Correct the test
52-84