Hach DR/700 Procedures Manual page 12

If sample
cannot be
run
immediately,
follow these
steps
PHOSPHORUS, REACTIVE,
10.
Insert the
AccuVac Vial Adapter
into the cell holder.
Table 2. Conversion Factors
To convert reading from
mg/L PO mg/L P
4
mg/L PO
4
SAMPLING AND STORAGE
Collect sample in plastic or glass bottles that have cleaned with 1:1
Hydrochloric Acid Solution and rinsed with deionized water. Do not use
commercial detergents containing phosphate for cleaning glassware used in
phosphate analysis.
Most reliable results are obtained when samples are analyzed as soon as
possible after collection. If prompt analysis is impossible, preserve samples
up to 24 hours by storing at or below 4 C. For longer storage periods, add 4.0
mL of Mercuric Chloride Solution to each liter of sample taken and mix.
Use of mercuric chloride is discouraged whenever possible for health and
environmental considerations. Sample refrigeration is still required.
Samples preserved with mercuric chloride must have a sodium chloride level
of 50 mg/L or more to prevent mercury interference. Samples low in
chloride should be spiked with 0.1 g sodium chloride per liter of sample.
continued
11.
Place the
prepared sample in the
cell holder.
Note: In bright sunlight it
may be necessary to close
the cell compartment cover.
To Multiply by
O 0.747
2 5
mg/L P 0.326
81-52
xii
12.
Press:
READ
The display will count
down to 0. Then the
display will show the
results in mg/L
phosphate (as PO ).
4
Note: To convert results to
other units, see Table 2.