Hach DR2400 - Page 507

Nitrogen, Total
Nitrogen, Total
NitrogenTot_TNT_Other_PSD_Eng_Ody.fm Page 7 of 8
Method Performance
Precision
Standard: 10 mg/L NH
3
–N
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
An alkaline persulfate digestion converts all forms of nitrogen to nitrate.
Sodium metabisulfite is added after the digestion to eliminate halogen oxide
interferences. Nitrate then reacts with chromotropic acid under strongly acidic
conditions to form a yellow complex with an absorbance maximum at 410 nm.
Required Reagents
Quantity Required
Description Per Test Unit Cat. No.
Test ‘N Tube™ Total Nitrogen Reagent Set .................................................................... 50 vials...............26722-45
Required Apparatus
Adapter, 16-mm Cell ................................................................................1 ....................... each....................59457-00
COD Reactor, 115/230 VAC, North American Plug............................1 ....................... each....................45600-00
COD Reactor, 230 VAC, European Plug................................................1 ....................... each....................45600-02
Funnel, micro ............................................................................................1 ....................... each....................25843-35
Safety Shield, laboratory bench, 38 x 40 cm..........................................1 ....................... each....................50030-00
Test Tube Cooling Rack............................................................................1–3 ................... each....................18641-00
Required Standards
Ammonia Nitrogen Standard Solution as N, 100-mg/L .............................................. 500 mL...............24065-49
Ammonia Nitrogen Standard Sol., 10-mL Voluette
®
Ampule, 160-mg/L NH
3
–N .. 16/pkg...............21091-10
Primary Standard Set, Kjeldahl Nitrogen, 59-mL SCDB .............................................. 3/set...................22778-00
Water, deionized ................................................................................................................. 500 mL...................272-49
or
Water, organic-free.............................................................................................................. 500 mL...............26415-49
Program 95% Confidence Limits of Distribution
350 9.0–11.0 mg/L N
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.5 mg/L N