Hach DR/850 Procedures Manual page 373

PHOSPHORUS, ACID HYDROLYZABLE,
17.
Tightly cover the
vial with the instrument
cap.
Sampling and Storage
Accuracy Check
Note: Clean glassware with
1:1 hydrochloric acid
solution. Rinse with deionized
water. Do not use detergents
containing phosphate to clean
glassware.
18.
Press:
READ
The cursor will move to
the right, then the result
in mg/L phosphate
3-
(PO ) will be
4
displayed.
Note: Standard Adjust may
be performed using a
prepared standard (see
Section 1).
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, the sample may be preserved up to
48 hours by cooling to 4 °C (39 °F). Warm to room temperature
before testing.
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
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.
continued
3- .
4
373