Hach DR/850, Procedures Manual, Page: 365 / 460

365
Sampling and Storage
Collect samples in plastic or glass bottles that have been acid
cleaned with 1:1 Hydrochloric Acid Solution and rinsed with
deionized water. Do not use commercial detergents containing
phosphate for cleaning glassware used in this test.
Analyze samples immediately after collection for best results. If
prompt analysis is impossible, preserve samples for up to 48
hours by filtering immediately and storing at 4 °C. Warm to room
temperature before analyzing the sample.
Accuracy Check
Note: Clean glassware with
1:1 hydrochloric acid
solution. Rinse again with
deionized water. Do not use
detergents containing
phosphates to clean
glassware.
Standard Additions Method
a) Fill three 25-mL graduated mixing cylinders with 25 mL of
sample.
b) Snap the neck off a Phosphate PourRite Ampule Standard,
50 mg/L as PO
4
3- .
c) Use the TenSette Pipet to add 0.1 mL, 0.2 mL and 0.3 mL,
respectively, to the three 25-mL aliquots of sample
prepared in
step a . Mix well.
13.
Tightly cover the
vial with the instrument
cap.
14.
Press:
READ
The cursor will move to
the right, then the result
in mg/L phosphate
(PO
4
3-
) will be displayed.
Note: Standard Adjust may
be performed using a
prepared standard (see
Section 1).
PHOSPHORUS, REACTIVE,
continued