Hach DR/850 Procedures Manual page 231

Nitrogen, Free Ammonia and Chloramine (Mono), continued
Method Performance
Monochloramine Test
Free Ammonia Test
3. Analyze each spiked sample, following all steps of the
Monochloramine and Free Ammonia procedure. The
ammonia nitrogen concentration should increase 0.02 mg/L
for each 0.1 mL of standard added.
4. If these increases do not occur, see Standard Additions
(Section 1 of the DR/890 Procedures Manual) for more
information.
Standard Solution Method
Prepare a 0.20 mg/L ammonia nitrogen standard by diluting
2.00 mL of the Ammonia Nitrogen Standard Solution, 10 mg/L,
to 100 mL with dilution water. Or, using the TenSette Pipet,
prepare a 0.20 mg/L ammonia nitrogen standard by diluting
0.4 mL of a Ammonia Nitrogen Voluette Standard Solution,
50 mg/L as NH –N, to 100 mL with dilution water. Analyze the
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standard solution, following all steps of the Monochloramine and
Free Ammonia procedure.
Precision
In a single laboratory, using a monochloramine standard solution
of 2.10 mg/L Cl and representative lots of reagent, a single
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operator obtained a standard deviation of ± 0.12 mg/L Cl
Estimated Detection Limit
The estimated detection limit for Method 10171 is 0.05 mg/L Cl
Precision
In a single laboratory using a solution containing 1.80 mg/L Cl
plus 0.20 mg/L ammonia nitrogen (NH
representative lots of reagent with the DR/890, a single operator
obtained a standard deviation of ± 0.01 mg/L N for seven
replicates.
Estimated Detection Limit
The estimated detection limit for program 46 is 0.02 mg/L N.
For more information on the estimated detection limit, see
Section 1 of the DR/850 or DR/890 Procedure Manual.
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–N) and two
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