Hach DR/700 Procedures Manual page 150

PHOSPHORUS, REACTIVE,
SUMMARY OF METHOD
In the molybdovanadate method, orthophosphate reacts with molybdate
in an acid medium to produce a phosphomolybdate complex. In the
presence of vanadium, yellow vanadomolybdophosphoric acid is
formed. The intensity of the yellow color is proportional to the
phosphate concentration.
REQUIRED REAGENTS
Description
Molybdovanadate Reagent . . . 2.0 mL . . . . . 100 mL* MDB . . .20760-32
Water, demineralized . . . . . . . 25 mL . . . . . 4 L . . . . . . . . . . . . 272-56
REQUIRED APPARATUS
DR/700 Filter Module
Number 42.01. . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . 46242-00
OPTIONAL REAGENTS
Bromine Water . . . . . . . . . . . . . . . . . . . . . . . 29 mL* . . . . . . . 2211-20
Hydrochloric Acid Solution, 1:1 . . . . . . . . . 500 mL . . . . . . . . . 884-49
Mercuric Chloride Solution, 10 g/L . . . . . . . 100 mL . . . . . . . 14994-42
Phenol Solution, 30 g/L . . . . . . . . . . . . . . . . 29 mL . . . . . . . . 2112-20
Phosphate Standard Solution,
50 mg/L as PO
Phosphate Standard Solution, Voluette
ampule, 500 mg/L as PO
Sodium Chloride, ACS . . . . . . . . . . . . . . . . . 454 g . . . . . . . . .
Sodium Hydroxide
Standard Solution, 5.0 N . . . . . . . . . . . . . . 100 mL**MDB . . . 2450-32
Sulfuric Acid, ACS . . . . . . . . . . . . . . . . . . . . 500 mL* . . . . . . . . 979-49
Molybdovanadate Reagent . . . . . . . . . . . . . . 1000 mL . . . . . . 20760-53
OPTIONAL APPARATUS
Caps for 10- and 25-mL sample cells . . . . . . 12/pkg . . . . . . . . 24018-12
Dispenser, fixed volume,
1.0 mL Repipet Jr. . . . . . . . . . . . . . . . . . . each . . . . . . . . . . 21113-02
Flask, erlenmeyer, 50 mL . . . . . . . . . . . . . . . each . . . . . . . . . . . . 505-41
Flask, volumetric, Class A, 50 mL . . . . . . . . each . . . . . . . . . . 14574-41
pH Indicator Paper, 1 to 11 pH . . . . . . . . . . . 5 rolls/pkg . . . . . . . 391-33
pH Meter, EC10, portable . . . . . . . . . . . . . . each . . . . . . . . . . 50050-00
Quantity
Per Test
3-
. . . . . . . . . . . . . . . . . . . 500 mL . . . . . . . . . 171-49
4
3-
, 10 mL . . . . . 16/pkg . . . . . . . . 14242-10
4
42-66
continued
Units Cat. No.
182-01