Hach DR/700 Procedures Manual page 670

TANNIN AND LIGNIN,
10.
Press:
ZERO
The display will
count down to 0.
Then the display will
show 0.00 mg/L and
the zero prompt will
turn off.
SAMPLING AND STORAGE
Collect samples in clean plastic or glass bottles.
ACCURACY CHECK
Standard Solution Method
Prepare a 200-mg/L tannic acid stock solution by dissolving 0.200
grams of tannic acid in demineralized water and diluting to 1000 mL.
Prepare this solution monthly. Make a 2.0-mg/L tannic acid standard by
diluting 10.00 mL of the stock solution to 1000 mL with demineralized
water. Prepare this standard daily.
continued
11.
Place the
prepared sample in the
cell holder.
Note: Use a 10-mL cell
for the blank and the
sample in bright
sunlight.
69-10
12.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
mg/L tannic acid.