Hach DR2400 - Page 500

Nitrogen, Total
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 6 of 6 NitrogenTot_TNT_High_PSD_Eng_Ody.fm
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Method Performance
Precision
Standard: 100 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™ HR Total Nitrogen Reagent Set.............................................................. 50 vials...............27141-00
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
Pipet, TenSette
®
, 0.1 to 1.0 mL ................................................................1 ....................... each....................19700-01
Pipet Tips, for 19700-01 TenSette
®
Pipet ...............................................2 ....................... 50/pkg...............21856-96
Safety Shield ..............................................................................................1....................... each....................50030-00
Test Tube Cooling Rack............................................................................1–3 ................... each....................18641-00
Required Standards
Ammonia Nitrogen Standard Sol., 1000-mg/L NH
3
–N ............................................... 1 liter..................23541-53
Primary Standard Set, for Kjeldahl Nitrogen ................................................................. set of 3 ...............22778-00
Ammonia Nitrogen Standard Solution, 100-mg/L NH
3
–N......................................... 500mL................24065-49
Water, deionized........................................................................................................... 500 mL...................272-49
or Water, organic-free ....................................................................................................... 500 mL...............26415-49
Program 95% Confidence Limits of Distribution
395 94–106 mg/L N
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 2 mg/L N