50
•
Remove the cap and add the content of one packet of HI 93758-0
Phosphorus Reagent.
•
Replace the cap tightly and shake gently to mix for 2 minutes until most of
the powder is dissolved. This is the reacted sample.
•
Place the vial into the holder and push it completely down.
• Press
Timer
and the display will show the countdown prior to the
measurement and the “
Reaction Time
” message. Alternatively, wait for 3 minutes and press
Read
.
• The instrument will perform the reading. The instrument displays concentration in
mg/L of phosphorus
(P)
.
• Press
s
or
t
to convert the result in mg/L of phosphate (PO
4
3
-) or mg/L of P
2
O
5
.
Note
: For accurate measurements
1) wash glassware only with phosphate-free detergents
2) clean all glassware with 1 : 1 hydrochloric acid solution and rinse with deionized water.
INTERFERENCES
Interference may be caused by:
Arsenate at any level
Silica above 50 mg/L
Sulfide
above 6 mg/L.
To eliminate sulfide: add Bromine Water drop-wise until a pale yellow color develops; remove Bromine Water
excess by adding Phenol solution drop-wise.
Turbidity and suspended matter in large amounts may cause interference because the reaction conditions
may dissolve suspended matter or cause desorption of phosphates from particles. Turbidity or suspended
matter should be removed before measurement by treatment with active carbon and by prior filtration.
Phosphorus, Reactive