Hach DR2400 - Page 611

Phosphorus, Acid Hydrolyzable Digestion
Phosphorus, Acid Hydrolyzable Digestion
PhosphorusAcidHydro_Other_AD_Eng_Ody.fm Page 3 of 4
Summary of Method
Phosphates present in condensed inorganic forms (meta-, pyro- or other
polyphosphates) must be converted to reactive orthophosphate before analysis.
Pretreatment of the sample with acid and heat hydrolyzes the condensed
inorganic forms to orthophosphate.
This procedure must be followed by one of the reactive phosphorus
(orthophosphate) analysis methods for determining the phosphorus content of
the sample. If the ascorbic acid (PhosVer 3) method is used to measure the
reactive phosphorus, this method is USEPA accepted for NPDES reporting.
The following reagents and apparatus are required in addition to those required
for the active phosphorus test.
Required Reagents
Quantity Required
Description Per Test Unit Cat. No.
Sodium Hydroxide Solution, 5.0 N........................................................2 mL ................ 100 mL MDB.......2450-32
Sulfuric Acid Solution, 5.25 N ................................................................2 mL ................ 100 mL MDB.......2449-32
Water, deionized ................................................................................................................. 4 liters ....................272-56
Required Apparatus
Cylinder, graduated, 25-mL ....................................................................1 ....................... each........................508-40
Flask, Erlenmeyer, 125-mL ......................................................................1 ....................... each........................505-43
Hot Plate, 4 inch diameter, 120 VAC......................................................1 ....................... each....................12067-01
Hot Plate, 4 inch diameter, 240 VAC......................................................1 ....................... each....................12067-02
Required Apparatus (Field Applications)
Heatab Cookit, with 1 box heatabs .................................................................................. each......................2206-00
Heatab Replacements......................................................................................................... 21/pkg.................2207-00