Hach DR/850, Procedures Manual, Page: 384 / 460

384
Sample Disposal Information
Final samples will contain molybdenum. In addition, final
samples will have a pH less than 2 and are considered corrosive
(D002) by the Federal RCRA.
Summary of Method
Phosphates present in organic and condensed inorganic forms
(meta-, pyro- or other polyphosphates) must be converted to
reactive orthophosphate before analysis. Pretreatment of the
sample with acid and heat provides the conditions for hydrolysis
of the condensed inorganic forms. Organic phosphates are
converted to orthophosphate by heating with acid and persulfate.
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.
REQUIRED REAGENTS
Total Phosphorus Test ’N Tube Reagent Set ......................................50 tests ............. 27426-45
Includes: (1) 272-42, (1) 20847-66, (1) 21060-46, (1) 27430-42, (50) Acid Dilution Vials*
Quantity Required
Description Per Test Unit Cat. No.
PhosVer 3 Phosphate Reagent Powder Pillows ..................1 ..............50/pkg ............. 21060-46
Potassium Persulfate powder Pillows .................................1 ..............50/pkg ............. 20847-66
Sodium Hydroxide Solution, 1.54 N ........................... 2 mL ............ 100 mL ............. 27430-42
Test ‘N Tube Acid Dilution Vials .......................................1 ..............50/pkg
.................................. *
Water, deionized for reagent blank .............................. 5 mL ............ 100 mL ................. 272-42
REQUIRED APPARATUS
COD/TNT Adapter .............................................................1 ..................each ............. 48464-00
DRB 200 Reactor, 110 V, 15 x 16 mm tubes .................................................. LTV082.53.40001
DRB 200 Reactor, 220 V, 15 x 16 mm tubes.................................................. LTV082.52.40001
Funnel, micro ......................................................................1 ..................each ............. 25843-35
Test Tube Rack ............................................................... 1-3 ..................each ............. 18641-00
Pipet, TenSette, 1 to 10 mL.................................................1 ..................each ............. 19700-10
Pipet Tips, for 19700-10 TenSette Pipet ..................... varies ..............50/pkg ............. 21997-96
* These items are not sold separately.
PHOSPHORUS, TOTAL,
continued