PASCO EZ-2333A Nitrate ezSample - Manual (Page 2)

Test Method Description
The nitrate ezSample test method employs the zinc reduction method. 1,2,3,4 Nitrate is reduced to nitrite in the
presence of zinc. In an acidic solution, the nitrite diazotizes with a primary aromatic amine and then couples with
another organic molecule to produce a highly colored azo dye. The resulting pink-orange color is proportional to
the nitrate concentration.
Results are expressed in ppm (mg/L) NO
3
-N. To convert to ppm (mg/L) nitrate as NO
3
, multiply test results
by 4.4.
This test method is applicable to industrial wastewater, drinking water, surface water and seawater.
Test Procedure for Nitrite Nitrogen
This kit can also be used to measure nitrate in the presence of up to 0.4 ppm (mg/L) nitrite nitrogen (NO
2
-N) by
difference using the following procedure:
A. Fill the 25 mL sample cup to the 15 mL mark with sample.
B. Follow steps 5 through 7 of the test procedure to obtain a test result for nitrite-nitrogen in the sample.
C. If the test result obtained for nitrite-nitrogen is less than 0.4 ppm, this test result can be subtracted from a
nitrate-nitrogen test result (obtained on a separate aliquot of sample by following the full test procedure (Steps 1
through 7) to obtain accurate results for nitrate-nitrogen in the presence of low levels of nitrite-nitrogen.
Accuracy and practical detection limit (PDL)
The lower limit of the stated test range is the “Practical Detection Limit (PDL).” Accuracy may be compromised if
test results are outside of the test range. Test results obtained at or below the PDL should be further confirmed for
best accuracy.
References
1. Method 4500-NO3 E APHAStandard Methods, 20th ed., p. 4-117, (1998)
2. Nitrite-Nitrate in Water, Test Method B, ASTM D 3867 - 99
3. Method 353.3 EPA Methods for Chemical Analysis of Water and Wastes, (1983)
4. Nelson J. L., Kurtz, L. T., and R. H. Bray, R.H. Rapid Determination of Nitrates and Nitrites. Analytical
Chem., V26, p 1081-2 (1954)
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