81-30
PHOSPHORUS, REACTIVE, continued
ACCURACY CHECK
Standard Additions Method
a) Snap the neck of a Phosphate Voluette Ampule Standard, 25 mg/L as P.
b) Use the TenSette Pipet to add 0.1 mL, 0.2 mL and 0.3 mL,
respectively, to three 5-mL aliquots of a water samples. Mix well.
c) Analyze each sample as described in the procedure. The concentration
should increase 1.5 mg/L, 3.0 mg/L, 4.3 mg/L, respectively.
d) If these increases do not occur, see Standard Additions for more
information.
INTERFERENCES
Large amounts of turbidity may cause inconsistent results in the test
because the acid present in the powder pillows may dissolve some of the
suspended particles and because of variable desorption of
orthophosphate from the particles.
The PhosVer 3 Phosphate Reagent Powder Pillows should be stored in a
cool, dry environment.
The following may interfere when present in concentrations exceeding
these listed below:
Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . 200 mg/L
Chromium . . . . . . . . . . . . . . . . . . . . . . . . . 100 mg/L
Copper . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mg/L
Iron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mg/L
Nickel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 mg/L
Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mg/L
Silicate. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mg/L
Zinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 mg/L
Arsenate and hydrogen sulfide do interfere.
Highly buffered samples or extreme sample pH may exceed the
buffering capacity of the reagents and require sample pretreatment.
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