Hach DR2400 - Page 459

Nitrite
Nitrite
Nitrite_TNT_Low_DAZ_Eng_Ody.fm Page 3 of 4
Accuracy Check
Standard Solution Method
Preparing nitrite standards is difficult. A standard should be prepared by a
trained chemist. Hach recommends using the standard preparation instructions
in Standard Methods for the Examination of Water and Wastewater, 18th ed., under
the headings “Stock nitrite solution,” “Intermediate nitrite solution,” and
“Standard nitrite solution.” Prepare a 0.150-mg/L standard. Perform the nitrite
test on the standard solution.
Method Performance
Precision
Standard: 0.150 mg/L NO
2
–
–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
Nitrite in the sample reacts with sulfanilic acid to form an intermediate
diazonium salt. This couples with chromotropic acid to produce a pink colored
complex directly proportional to the amount of nitrite present. Test results are
measured at 507 nm.
Required Reagents
Quantity Required
Description per test Unit Cat. No.
NitriVer
®
3 Low Range Nitrite Test ‘N Tube™ Vial Set (50 tests) ............................................................26083-45
Required Apparatus
Adapter, 16-mm Cell ................................................................................1 ....................... each....................59457-00
Pipet, TenSette
®
, 1.0 to 10.0 mL ..............................................................1 ....................... each....................19700-10
Pipet Tips, for 19700-10 TenSette
®
Pipet ...............................................varies .............. 50/pkg...............21997-96
Required Standards
Sodium Nitrite, ACS .......................................................................................................... 454 g.....................2452-01
Water, deionized ................................................................................................................. 4 liters ....................272-56
Program 95% Confidence Limits of Distribution
345 0.146–0.154 mg/L NO
2
–
–N
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.003 mg/L NO
2
–
–N