Hach DR2400 - Page 617

Phosphorus, Reactive
Phosphorus, Reactive
PhosphorusReac_PT_Low_ASC_Eng_Ody.fm Page 5 of 6
Method Performance
Precision
Standard: 1000 µg/L PO
4
3–
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
See Section 3.4.5 Sensitivity on page 44 for more information.
Summary of Method
Orthophosphate reacts with molybdate in an acid medium to produce a
phosphomolybdate complex. Ascorbic acid then reduces the complex, giving an
intense molybdenum blue color. Reactive phosphorus includes existing
orthophosphate in the sample plus a small fraction of condensed phosphate that
may be hydrolyzed to orthophosphate during the test. Test results are measured
at 880 nm.
Required Reagents
Quantity Required
Description Per Test Unit Cat. No.
Rapid Liquid Low Range Phosphorus Reagent Set ...................................................................................26786-00
Includes:
Ascorbic Acid Reagent Dilution Solution ......................................1 mL ................ 450 mL...............25999-49
Ascorbic Acid Reagent Powder ................................................................................. 48 g.....................26512-55
Molybdate Reagent Solution ............................................................2 mL ................ 500 mL...............25998-49
Water, deionized ................................................................................................................. 4 L ..........................272-56
Required Apparatus
Adapter, multi-pathlength cell ...............................................................1 ....................... each....................59466-00
Cylinder, graduated, 25-mL, poly ..........................................................2 ....................... each......................1081-40
Dispenser, fixed volume, 1.0-mL w/bottle...........................................2 ....................... each....................21113-02
Flask, Erlenmeyer, 125-mL, PMP w/cap...............................................2 ....................... each....................20898-43
Pour-Thru Cell Assembly........................................................................1 ....................... each....................59404-00
Required Standards
Phosphate Standard Solution, 1.00-mg/L as PO
4
3–
...................................................... 500 mL.................2569-49
Phosphate Standard Solution, Voluette
®
ampule, 10-mL, 50-mg/L PO
4
3–
............... 16/pkg...................171-10
Phosphate Standard Solution, 15-mg/L PO
4
3–
.............................................................. 100 mL...............14243-42
Program 95% Confidence Limits of Distribution
488 976–1024 µg/L PO
4
3–
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 19 µg/L PO
4
3–