Hach DR/850, Procedures Manual, Page: 344 / 460

344
Sampling and Storage
Collect samples in clean plastic or glass bottles that have been
cleaned with 1:1 Hydrochloric Acid Solution and rinsed with
deionized water.
Do not use a commercial detergent. If prompt analysis is
impossible, adjust the pH to 2 or less with about 2 mL of sulfuric
acid, ACS, per liter of sample. Store at 4 °C (39 °F) or below.
Preserved samples can be stored at least 24 hours. See
Section 1
for more information on dilution factors, cleaning instructions,
etc.
Accuracy Check
Ideally, a solution containing a known amount of the phosphonate
product being used should be prepared. This will check the UV
conversion of phosphonate to orthophosphate.
Interferences
When testing a 5-mL sample volume, the following may interfere
when present in concentrations exceeding those listed below:
The interference levels will decrease as the sample size increases.
For example, copper does not interfere at or below 100 mg/L for
a 5.00 mL sample. If the sample volume is increased to 10.00 mL,
copper will begin to interfere above 50 mg/L.
Table 2 Table 3
Sample Volume (mL)
(chosen in Step 3)
Multiplier
50 0.1
25 0.2
10 0.5
5 1.0
1 5.0
Phosphate concentration = Instrument Reading x
Multiplier
Phosphonate Type Conversion Factor
PBTC 2.84
NTP 1.050
HEDPA 1.085
EDTMPA 1.148
HMDTMPA 1.295
DETPMPA 1.207
HPA 1.49
Active Phosphonate (mg/L) = Phosphate con-
centration from Step 15 x Conversion Factor
PHOSPHONATES,
continued