ASTM D1426-15(2021)e1
(Test Method)Standard Test Methods for Ammonia Nitrogen In Water
Standard Test Methods for Ammonia Nitrogen In Water
SIGNIFICANCE AND USE
4.1 Nitrogen is a nutrient in the environment and is necessary to sustain growth of most organisms. It exists in several forms such as nitrate, nitrite, organic nitrogen such as proteins or amino acids, and ammonia.
4.2 Ammonia is a colorless, gaseous compound with a sharp distinctive odor. It is highly soluble in water where it exists in a molecular form associated with water and in an ionized form as NH4+. The extent of association or ionization is dependent on the temperature and pH. It may also be toxic to aquatic life. The extent of toxicity is dependent upon species and extent of dissociation.4 Ammonia may occur in water as a product of anaerobic decomposition of nitrogen containing compounds or from waste streams containing ammonia.
SCOPE
1.1 These test methods cover the determination of ammonia nitrogen, exclusive of organic nitrogen, in water. Two test methods are included as follows:
Sections
Test Method A—Direct Nesslerization
7 – 16
Test Method B—Ion Selective Electrode
17 – 24
1.2 Test Method A is used for the routine determination of ammonia in steam condensates and demineralizer effluents.
1.3 Test Method B is applicable to the determination of ammonia nitrogen in the range from 0.5 to 1000 mg NH3N/L directly in reagent and effluent waters. Higher concentrations can be determined following dilution. The reported lower range is based on multiple-operator precision. Lower limits have been obtained by two of the twelve laboratories participating in the round robin.
1.4 Both test methods A and B are applicable to surface and industrial waters and wastewaters following distillation. The test method for distillation given in Appendix X1 has been used in the past to meet requirements for predistillation of samples being analyzed for ammonia.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 The distillation method now appears as Appendix X1 and is provided as nonmandatory information only. The automated colorimetric phenate method has been discontinued.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
´1
Designation: D1426 − 15 (Reapproved 2021)
Standard Test Methods for
Ammonia Nitrogen In Water
This standard is issued under the fixed designation D1426; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—The WTO caveat was editorially added in November 2021.
1. Scope 1.8 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 These test methods cover the determination of ammonia
ization established in the Decision on Principles for the
nitrogen, exclusive of organic nitrogen, in water. Two test
Development of International Standards, Guides and Recom-
methods are included as follows:
mendations issued by the World Trade Organization Technical
Sections
Barriers to Trade (TBT) Committee.
Test Method A—Direct Nesslerization 7–16
Test Method B—Ion Selective Electrode 17–24
2. Referenced Documents
1.2 Test Method A is used for the routine determination of
2.1 ASTM Standards:
ammonia in steam condensates and demineralizer effluents.
D1066 Practice for Sampling Steam
1.3 Test Method B is applicable to the determination of
D1129 Terminology Relating to Water
ammonia nitrogen in the range from 0.5 to 1000 mg NH N/L
3 D1193 Specification for Reagent Water
directly in reagent and effluent waters. Higher concentrations
D2777 Practice for Determination of Precision and Bias of
can be determined following dilution. The reported lower
Applicable Test Methods of Committee D19 on Water
range is based on multiple-operator precision. Lower limits
D3370 Practices for Sampling Water from Flowing Process
have been obtained by two of the twelve laboratories partici-
Streams
pating in the round robin.
D5810 Guide for Spiking into Aqueous Samples
D5847 Practice for Writing Quality Control Specifications
1.4 Both test methodsAand B are applicable to surface and
for Standard Test Methods for Water Analysis
industrial waters and wastewaters following distillation. The
E60 Practice for Analysis of Metals, Ores, and Related
test method for distillation given in Appendix X1 has been
Materials by Spectrophotometry
used in the past to meet requirements for predistillation of
E275 Practice for Describing and Measuring Performance of
samples being analyzed for ammonia.
Ultraviolet and Visible Spectrophotometers
1.5 The values stated in SI units are to be regarded as
2.2 APHA Standard:
standard. No other units of measurement are included in this
Standard Methods for the Examination of Water and Waste
standard.
Water
1.6 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety, health, and environmental practices and deter-
3.1.1 For definitions of terms used in this standard, refer to
mine the applicability of regulatory limitations prior to use.
Terminology D1129.
1.7 The distillation method now appears as Appendix X1
4. Significance and Use
and is provided as nonmandatory information only. The auto-
mated colorimetric phenate method has been discontinued.
4.1 Nitrogen is a nutrient in the environment and is neces-
sary to sustain growth of most organisms. It exists in several
1 2
These test methods are under the jurisdiction of ASTM Committee D19 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Water and are the direct responsibility of Subcommittee D19.05 on Inorganic contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Constituents in Water. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2021. Published December 2021. Originally the ASTM website.
approved in 1956. Last previous edition approved in 2015 as D1426 – 15. DOI: AvailablefromAmericanPublicHealthAssociation,800ISt.NW,Washington,
10.1520/D1426-15R21E01. DC 20001, http://www.apha.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D1426 − 15 (2021)
forms such as nitrate, nitrite, organic nitrogen such as proteins 8. Summary of Test Method
or amino acids, and ammonia.
8.1 Asample aliquot is Nesslerized directly and the ammo-
4.2 Ammoniaisacolorless,gaseouscompoundwithasharp nia content determined colorimetrically.
distinctive odor. It is highly soluble in water where it exists in
9. Interferences
a molecular form associated with water and in an ionized form
+
as NH . The extent of association or ionization is dependent
4 9.1 Glycine, urea, glutamic acid, cyanates, and acetamide
on the temperature and pH. It may also be toxic to aquatic life.
hydrolyze very slowly in solution on standing, but, of these,
The extent of toxicity is dependent upon species and extent of
only urea and cyanates will hydrolyze on distillation at a pH of
dissociation. Ammonia may occur in water as a product of
9.5. Glycine, hydrazine, and some amines will react with
anaerobic decomposition of nitrogen containing compounds or
Nessler’s reagent to give the characteristic yellow color in the
from waste streams containing ammonia.
time required for the test. Similarly, volatile alkaline com-
pounds such as hydrazine and the amines will influence
5. Purity of Reagents
titrimetric results. Some organic compounds such as ketones,
5.1 Reagent grade chemicals shall be used in all tests.
aldehydes, alcohols, and some amines may cause an off color
Unless otherwise indicated, it is intended that all reagents shall
on Nesslerization. Some of these, such as formaldehyde may
conform to the specifications of the Committee on Analytical
beeliminatedbyboilingoffatalowpHpriortoNesslerization.
Reagents of the American Chemical Society, where such
Residual chlorine must be removed prior to the ammonia
specifications are available. Other grades may be used, pro-
determination by pretreatment of the sample.
vided it is first ascertained that the reagent is of sufficiently
9.2 Turbid samples may be clarified with ZnSO and NaOH
high purity to permit its use without lessening the accuracy of
solution; the precipitated Zn(OH) is filtered off, discarding the
the determination.
first 25 mL of filtrate, and the ammonia is determined on an
5.2 Unless otherwise indicated, references to water shall be
aliquot of the remaining clear filtrate by direct Nesslerization.
understood to mean reagent water conforming to Specification
Ammonia can be lost in basic conditions. Check procedure
D1193,Type I. In addition, this water shall be free of ammonia
with a standard solution.
nitrogen.Suchwaterisbestpreparedbythepassageofdistilled
water through an ion-exchange resin. These resins should also 10. Apparatus
be selected so that organic compounds which might subse- 3
10.1 Nessler Tubes—Matched Nessler tubes about 300 mm
quently interfere with the ammonia determination will be
long, 17-mm inside diameter, and marked for 50 mL at 225 6
removed. Regeneration of the ion-exchange materials should
1.5 mm from inside the bottom.
be carried out in accordance with the instructions of the
10.2 Photometer—Filter photometer or spectrophotometer
manufacturer.
suitable for absorbance measurements at 425 nm. Filter pho-
tometers and photometric practices used in this test method
6. Sampling
shall conform to Practice E60. Spectrophotometers shall con-
6.1 Collect the sample in accordance with Practices D1066
form to Practice E275.
and D3370, as applicable.
10.3 Stoppers—Rubber, size No. 2, to fit Nessler tubes.
6.2 Preserve the samples by the addition of 1 mL of
These stoppers shall be boiled in H SO (1 + 99), rinsed,
2 4
concentrated sulfuric acid per litre and store at 4°C. The pH
boiled in NaOH solution (1 g/L), rinsed, allowed to stand in
should be 2.0 or less. Analyze the samples within 24 h of
dilute Nessler reagent for 30 min, and then rinsed again.
sampling. Do not use mercuric chloride as a preservative.
NOTE1—Thispreservationprocedurewillconvertcyanatetoammonia. 11. Reagents and Materials
The user must be cautioned not to acidify samples if they contain
11.1 Ammonia Nitrogen Solution, Standard (1 mL = 0.01
cyanates. The preservation can extend the holding time to 28 days;
mg N)—Dry reagent grade ammonium sulfate ((NH ) SO )
however, the user will need to confirm the actual holding time.
4 2 –4
for1hat 100°C. Accurately weigh 4.718 g and dissolve in
TEST METHOD A—DIRECT NESSLERIZATION
water. Dilute to 1 L in a volumetric flask. Pipet 10 mL of this
stock solution to a 1-L volumetric flask and dilute to volume
7. Scope
with water. A purchased ammonia nitrogen stock solution of
7.1 This test method is suitable for the rapid routine
appropriate known purity is also acceptable.
determination of ammonia nitrogen in steam condensates and
NOTE 2—Ammonia standards should be stored in an area free from
demineralized water. See Appendix X1 for the distillation test
ambient ammonia vapors.
method.
11.2 Disodium Dihydrogen Ethylenediamine Tetraacetate
Solution (500 g/L)—Dissolve 500 g of disodium dihydrogen
Quality Criteria for Water, USEPA-440/9-76-023, July 26, 1976, pp. 16–24.
ethylenediamine tetraacetate dihydrate in water containing 100
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
g of NaOH. Gently heat to complete dissolution. Cool and
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical dilute to 1 L.
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
11.3 Filter Paper—Purchase suitable filter paper. Typically
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
copeial Convention, Inc. (USPC), Rockville, MD. the filter papers have a pore size of 0.45-µm membrane.
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D1426 − 15 (2021)
Material such as fine-textured, acid-washed, ashless paper, or the filtrate. Dilute a portion of the filtrate or clear sample,
glass fiber paper are acceptable. The user must first ascertain containing not more than 0.1 mg of ammonia nitrogen, to 50
that the filter paper is of sufficient purity to use without mLinaNesslertube.Add2dropsofsodiumpotassiumtartrate
adversely affecting the bias and precision of the test method. solution (11.6) (or disodium dihydrogen ethylenediamine tet-
raacetate [11.2]) to prevent cloudy tubes, and mix. Add 1 mL
11.4 Nessler Reagent—Dissolve 100 g of anhydrous mercu-
of Nessler solution (11.4) and measure photometrically at a
ric iodide (HgI ) and 70 g of anhydrous potassium iodide (KI)
wavelength of 425 nm.
in a small volume of water. Add this mixture slowly, with
stirring, to a cooled solution of 160 g of sodium hydroxide 13.2 If a visual comparison method is used, select a volume
(NaOH) in 500 mL of water. Dilute the mixture to 1 L. Store containing not more than 0.04 mg of ammonia nitrogen and
the solution in the dark for five days and filter twice, either dilute to 50 mL. Mix, add 1 mL of Nessler reagent (11.4), and
through a fritted glass crucible or glass fiber filter before using. remix. Compare the color developed after 10 min with the
If this reagent is stored in a chemically resistant bottle out of previously prepared standards. If the ammonia nitrogen con-
direct sunlight, it will remain stable up to a period of 1 year.A centrationisbelow0.008mg(inthe50-mLtube)compareafter
purchased solution of appropriate known purity is also accept- 30 min.
able.
14. Calculation
NOTE 3—This reagent should give the characteristic color with ammo-
14.1 Calculate the ammonia concentration in mg/Lof nitro-
nia within 10 min after addition, and should not produce a precipitate with
gen in the original sample, using Eq 1:
small amounts of ammonia (0.04 mg in a 50-mL volume). The solution
may be used without 5-day storage if it is filtered through a 0.45 µm
Ammonia nitrogen, mg/L 5 A 31000 /S (1)
@~ ! #
membrane (previously rinsed with reagent water Type I (see Specification
D1193)) shortly before use.
where:
NOTE 4—Mercury and its salts are hazardous materials.They should be
A = ammonia nitrogen observed, mg, and
stored, handled and dispensed accordingly. Disposal of solutions must be
S = sample, mL.
made by legally acceptable means.
14.2 Calculate the ammonia concentration in mg/L of am-
11.5 Sodium Hydroxide Solution (240 g/L)—Dissolve 240 g
monia in the original sample, using Eq 2:
of NaOH in water and dilute to 1 L.
Ammonia, mg/L 5 E 31.22 (2)
11.6 Sodium Potassium Tartrate Solution (300 g/L)—
Dissolve 300 g of sodium-potassium tartrate tetrahydrate in 1
where:
L of water. Boil until ammonia-free and dilute to 1 L.
E = ammonia nitrogen, mg/L.
11.7 Zinc Sulfate Solution (100 g/L)—Dissolve 100 g of
15. Precision and Bias
zinc sulfate heptahydrate (ZnSO ·7H O) in water and dilute to
4 2
1L. 15.1 The precision of this test method was measured with-
out the use of any distillation procedure by nine laboratories in
12. Calibration
reagent water only at four levels in the range from 30 to 100
12.1 Prepare a series of standards containing the following mg/L NH -N, and each concentration was done in triplicate.
The test method was tested in reagent water because steam
volumes of standard ammonia nitrogen solution diluted to 50
mL with water: 0.0, 1.0, 3.0, 5.0, 8.0, and 10.0 mL. Mix, add condensates and demineralized effluents are similar to reagent
water.
1 mLof Nessler reagent (11.4), and remix.After 20 to 30 min,
using a photometer suitable for absorbance measurement at
15.2 Analysts using Test MethodAin any matrix other than
425 nm and a compensatory blank (Nesslerized ammonia-free
a steam condensate or demineralized effluent must show the
water), prepare a calibration curve based on a series of these
applicability of this test method to that matrix.
standards.Analyze at least three working standards containing
15.3 The precision of Test Method A in reagent water was
concentrations of ammonia nitrogen that bracket the expected
0.04 mg/Lat 1.0 mg/LNH -N. Other precision data are shown
sample concentration prior to analysis of samples to calibrate
in Table 1.
the instrument.
15.4 Precision and bias for this test method conforms to
12.2 If a visual comparison method is used, prepare a series
Practice D2777 – 77, which
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