ASTM D3867-16(2021)e1

Standard Test Methods for Nitrite-Nitrate in Water

SIGNIFICANCE AND USE
5.1 Both test methods use identical reagents and sample processing. The only difference between the two methods is that one test method is automated and the other is manual. The ranges and interferences are identical.  
5.2 The automated test method is preferred when large numbers of samples are to be analyzed. The manual test method is used for fewer samples or when automated instrumentation is not available.  
5.3 These test methods replace Test Methods D1254 (Nitrite) and D992 (Nitrate). The nitrite test method (Test Method D1254) used a reagent that is considered to be a potential carcinogen. The nitrate test method (Test Method D992) has been shown to have relatively large errors when used in wastewaters and also has greater manipulative difficulties than the test method described herein.  
5.4 Test Method D7781 uses a nitrate reductase enzyme for the reduction of nitrate to nitrite. Cadmium is considered a toxic metal. Also, the heterogeneous cadmium reductant creates greater difficulty than the reduction described in this test method.
SCOPE
1.1 These test methods cover the determination of nitrite nitrogen, nitrate nitrogen, and combined nitrite-nitrate nitrogen in water and wastewater in the range from 0.05 to 1.0 mg/L nitrogen. Two test methods2 are given as follows:    
Sections  
Test Method A—Automated Cadmium Reduction  
9 to 18  
Test Method B—Manual Cadmium Reduction  
19 to 28  
1.2 These test methods are applicable to surface, saline, waste, and ground waters. It is the user's responsibility to ensure the validity of these test methods for waters of untested matrices.  
1.3 The values stated in either SI or inch-pound units are to be regarded as the standard. No other units of measurement are included in this standard.  
1.4 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.  For specific hazard statements, see 8.2.  
1.5 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

• Status: Published
• Publication Date: 31-Oct-2021
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D2777-12 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jun-2012
• Refers: ASTM D5810-96(2011) - Standard Guide for Spiking into Aqueous Samples
• Effective Date: 01-May-2011
• Refers: ASTM D3370-10 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2010
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM E275-08 - Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
• Effective Date: 15-Oct-2008
• Refers: ASTM D3370-08 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Oct-2008
• Refers: ASTM D1141-98(2008) - Standard Practice for the Preparation of Substitute Ocean Water
• Effective Date: 15-Jul-2008
• Refers: ASTM D2777-08 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jan-2008
• Refers: ASTM D3370-07 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2007
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D5810-96(2006) - Standard Guide for Spiking into Aqueous Samples
• Effective Date: 15-Aug-2006
• Refers: ASTM D2777-06 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Aug-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006

Overview

ASTM D3867-16(2021)e1 – Standard Test Methods for Nitrite-Nitrate in Water is an internationally recognized standard developed by ASTM International. It specifies robust procedures for determining nitrite nitrogen, nitrate nitrogen, and their combined concentrations in water and wastewater samples. The methods operate effectively within a range of 0.05 to 1.0 mg/L nitrogen and are suitable for various water types, including surface waters, saline waters, wastewaters, and groundwater.

The standard presents two distinct, yet chemically identical, test methods:

• Test Method A: Automated cadmium reduction for high-throughput environments.
• Test Method B: Manual cadmium reduction for low-volume or settings without automated analyzers.

These methods supersede previous standards that posed safety or accuracy challenges, making ASTM D3867-16(2021)e1 a safer and more reliable approach for environmental and industrial water analysis.

Key Topics

• Scope and Application: The standard accurately quantifies nitrite and nitrate nitrogen in a range of water matrices, supporting both environmental monitoring and industrial applications.
• Testing Methodologies: Both automated and manual cadmium reduction methods are included, using identical reagents and sample preparations to maintain consistency in results.
• Interferences and Sample Integrity: Addresses potential issues such as turbidity, color, oil and grease, metal ion interference, and proper sample preservation to ensure accurate analyses.
• Health and Safety: Notes the toxic nature of cadmium used in reduction columns and provides important guidance on the safe handling and storage of reagents and samples.
• Quality Control: Emphasizes calibration with standard solutions, regular verification, quality control samples, and adherence to best laboratory practices to maintain data precision and accuracy.
• International Standardization: Developed following internationally recognized guidelines, ensuring global applicability and acceptance.

Applications

ASTM D3867-16(2021)e1 is widely used in:

• Environmental monitoring: Supporting regulatory compliance and water quality surveillance by public utilities, government agencies, and environmental laboratories.
• Industrial wastewater analysis: Helping industries meet discharge regulations by accurately measuring levels of nitrite and nitrate nitrogen in effluent streams.
• Drinking water testing: Ensuring safety and compliance in municipal water supplies and groundwater sources.
• Research and academic laboratories: Providing a reliable framework for scientific studies involving nitrogen species in aquatic environments.
• Quality assurance programs: Underpinning laboratory accreditation and routine quality assessments for water analysis.

By enabling both automated and manual approaches, the standard offers flexibility for laboratories of all sizes, ensuring dependable results regardless of sample volume or resource availability.

Related Standards

Professionals utilizing ASTM D3867-16(2021)e1 may also reference:

• ASTM D1129: Terminology relating to water.
• ASTM D1141: Preparation of substitute ocean water.
• ASTM D1193: Reagent water specifications.
• ASTM D2777: Precision and bias determination for water analysis methods.
• ASTM D3370: Sampling water from flowing process streams.
• ASTM D5847: Writing quality control specifications for water analysis.
• ASTM D7781: Nitrite-nitrate in water by nitrate reductase.
• EPA Methods: U.S. Environmental Protection Agency methods for water analysis.
• ISO Standards: Comparable international guidance for nitrate and nitrite measurement.

Adoption of ASTM D3867-16(2021)e1 assures comprehensive, reliable, and globally recognized methodologies for nitrite and nitrate determination in diverse water samples, supporting both regulatory compliance and environmental protection efforts.

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: D3867 − 16 (Reapproved 2021)
Standard Test Methods for
Nitrite-Nitrate in Water
This standard is issued under the fixed designation D3867; 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.
ε NOTE—The WTO caveat was editorially added and warning notes were editorially updated throughout in November
2021.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 These test methods cover the determination of nitrite
D992 Method of Test for Nitrate Ion in Water (Withdrawn
nitrogen, nitrate nitrogen, and combined nitrite-nitrate nitrogen
1983)
in water and wastewater in the range from 0.05 to 1.0 mg/L
D1129 Terminology Relating to Water
nitrogen. Two test methods are given as follows:
D1141 Practice for Preparation of Substitute Ocean Water
Sections
D1193 Specification for Reagent Water
Test Method A—Automated Cadmium Reduction 9 to 18
Test Method B—Manual Cadmium Reduction 19 to 28 D1254 Method of Test for Nitrite Ion in Water (Withdrawn
1980)
1.2 These test methods are applicable to surface, saline,
D2777 Practice for Determination of Precision and Bias of
waste, and ground waters. It is the user’s responsibility to
Applicable Test Methods of Committee D19 on Water
ensure the validity of these test methods for waters of untested
D3370 Practices for Sampling Water from Flowing Process
matrices.
Streams
D5810 Guide for Spiking into Aqueous Samples
1.3 The values stated in either SI or inch-pound units are to
D5847 Practice for Writing Quality Control Specifications
be regarded as the standard. No other units of measurement are
for Standard Test Methods for Water Analysis
included in this standard.
D7781 Test Method for Nitrite-Nitrate in Water by Nitrate
1.4 This standard does not purport to address all of the
Reductase
safety concerns, if any, associated with its use. It is the
E60 Practice for Analysis of Metals, Ores, and Related
responsibility of the user of this standard to establish appro-
Materials by Spectrophotometry
priate safety, health, and environmental practices and deter-
E275 Practice for Describing and Measuring Performance of
mine the applicability of regulatory limitations prior to use.
Ultraviolet and Visible Spectrophotometers
For specific hazard statements, see 8.2.
3. Terminology
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.1 Definitions:
ization established in the Decision on Principles for the
3.1.1 For definitions of terms used in this standard, refer to
Development of International Standards, Guides and Recom-
Terminology D1129.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Summary of Test Methods
4.1 Total Oxidized Nitrogen—A filtered sample is passed
through a column containing copper-coated cadmium granules
to reduce nitrate ion to nitrite ion. The combined nitrite-nitrate
nitrogen is determined by diazotizing the total nitrite ion with
These test methods are under the jurisdiction of ASTM Committee D19 on
Water and are the responsibility of Subcommittee D19.05 on Inorganic Constituents
in Water. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2021. Published December 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1979. Last previous edition approved in 2016 as D3867 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D3867-16R21E01. the ASTM website.
2 4
Methods similar to these appear in Methods of Chemical Analysis of Water and The last approved version of this historical standard is referenced on
Wastes, 2nd edition, U.S. Environmental Protection Agency. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D3867 − 16 (2021)
sulfanilamide and coupling with N-(1- The use of chlorine-containing Type II water will lead to a
naphthyl)ethylenediamine dihydrochloride to form a highly negative interference because nitrite and chlorine do not
colored azo dye that is measured spectrophotometrically. normally coexist. This is of particular importance when pre-
paring standards or spiked samples (Guide D5810).
4.2 Nitrite—The nitrite ion originally present in the sample
canbedeterminedseparatelybycarryingouttheprocedureand
6.6 In acid samples (pH less than 4.5) nitrate is not reduced
omitting the cadmium reduction step.
in the cadmium column. To overcome this interference, the
sample must be neutralized to a pH of between 6 and 8 prior to
4.3 Nitrate—The nitrate ion can be calculated as the differ-
analysis.
ence between the combined nitrite-nitrate nitrogen and the
nitrite nitrogen.
7. Purity of Reagents
5. Significance and Use
7.1 Reagent grade chemicals shall be used in all tests.
Unless otherwise indicated, it is intended that all reagents shall
5.1 Both test methods use identical reagents and sample
processing. The only difference between the two methods is conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, when such
that one test method is automated and the other is manual. The
ranges and interferences are identical. specifications are available. Other grades may be used, pro-
vided it is first ascertained that the reagent is of sufficient high
5.2 The automated test method is preferred when large
purity to permit its use without lessening the accuracy of the
numbers of samples are to be analyzed. The manual test
determination.
method is used for fewer samples or when automated instru-
mentation is not available.
7.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water conforming
5.3 These test methods replace Test Methods D1254 (Ni-
to Specification D1193, Type I. Other reagent water types may
trite) and D992 (Nitrate). The nitrite test method (Test Method
be used, provided it is first ascertained that the water is of
D1254) used a reagent that is considered to be a potential
sufficiently high purity to permit its use without adversely
carcinogen. The nitrate test method (Test Method D992) has
affecting the bias and precision of these test methods. Type II
been shown to have relatively large errors when used in
water was specified at the time of round-robin testing of these
wastewaters and also has greater manipulative difficulties than
test methods.
the test method described herein.
5.4 Test Method D7781 uses a nitrate reductase enzyme for
8. Sampling and Sample Preservation
the reduction of nitrate to nitrite. Cadmium is considered a
8.1 Collect the sample in accordance with Practices D3370.
toxic metal. Also, the heterogeneous cadmium reductant cre-
ates greater difficulty than the reduction described in this test
8.2 When nitrite ion is to be determined separately, analyze
method.
as soon as possible after sampling. Even when sterile bottles
are used, bacteria naturally present in the water may cause
6. Interferences
conversion of all or part of nitrite ion to other forms such as
6.1 Turbid samples must be filtered prior to analysis to
nitrate or ammonia. Ammonia and natural amines, which are
eliminate particulate interference. Furthermore, sample turbid-
frequently present in natural waters, may react with nitrites to
ity results in a buildup on the reduction column that restricts
form nitrogen. If samples are to be stored for 24 h or less,
sample flow.
preserve the sample by refrigeration at 4°C. If the sample must
be stored for more than 24 h, preserve it by the addition of 2
6.2 Sample color that absorbs at wavelengths between 520
mL of chloroform per litre (11.7 and 11.9) in addition to
and 540 nm interferes with the absorbance measurements.
refrigeration at 4°C. (Warning—Chloroform is toxic and is a
When color is suspect, analyze a sample blank, omitting the
suspected human carcinogen. Use with adequate ventilation or
N-(1-naphthyl)ethylenediamine dihydrochloride from the color
in a fume hood. Wear prescribed protective equipment. Use of
reagent.
chloroform is discouraged, since its use renders the solution a
6.3 Oil and grease in the sample coat the surface of the
hazardous waste.) (Caution—The common prescribed use of
cadmium and prevent complete reduction of nitrate to nitrite.
sulfuric acid or mercury compounds as preservatives is dis-
This interference is usually removed by filtration prior to
couraged. Sulfuric acid does not necessarily inhibit oxidation
analysis. If filtration is not adequate, the interference can be
and mercury compounds should be avoided to prevent envi-
removed by extracting the sample with an n-hexane or a solid
ronmental pollution. Mercuric chloride is known to deactivate
phase extraction (SPE) filter.
the column.)
6.4 Certain metal ions, in concentrations above 35 mg/L,
may cause interferences. For example, Hg (II) and Cu (II) may
form colored complex ions having absorption bands in the
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
region of color measurement. Iron and manganese are other
Standard-Grade Reference Materials, American Chemical Society, Washington,
reported examples of interference. DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
6.5 Excessiveamountsofchlorinewilldeactivatethereduc-
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
ing column. Chlorine might be present in some Type II water. copeial Convention, Inc. (USPC), Rockville, MD.
´1
D3867 − 16 (2021)
FIG. 1 Nitrite-Nitrate Manifold
TEST METHOD A—AUTOMATED CADMIUM 10.2 Reduction Columns—Choosetheappropriatereduction
REDUCTION column for the manifold system. A schematic drawing of the
manifold system is shown in Fig. 1 and the cartridge system is
9. Scope shown in Fig. 2.
10.2.1 Reduction Column, a glass tube 8 by 50 mm with the
9.1 The applicable range of this test method is from 0.05 to
ends reduced in diameter to permit insertion into the system
1 mg/L of nitrite or nitrate nitrogen. The range may be
(see Fig. 1).
extended upward by dilution of an appropriate aliquot. Many
10.2.2 Reduction Column, a U-shaped glass tubing,
workers have found that this test method is reliable for nitrite
350-mm length and 2-mm inside diameter.
and combined nitrite-nitrate levels to 0.01 mg N/L. However,
the precision and bias data presented in this test method are
NOTE 1—Apump tube with 0.081-in. (2.1-mm) inside diameter can be
used in place of the 2-mm glass tube.
insufficient to justify application of this test method in the 0.01
to 0.05 mg/L-N range.
11. Reagents and Materials
9.2 This test method is applicable to surface, saline, waste,
11.1 Ammonium Chloride Solution (85 g/L)—Dissolve 85 g
and ground waters. It is the user’s responsibility to ensure the
ofammoniumchloride(NH Cl)inwateranddiluteto1L.Add
validity of this test method for waters of untested matrices.
0.5 mL wetting agent.
10. Apparatus
11.2 Cadmium, 40 to 60 mesh, granulated.
10.1 Automated Analysis System consisting of:
11.3 ColorReagent—Addthefollowingto800mLofwater,
10.1.1 Sampler.
while stirring constantly: 100 mL of concentrated phosphoric
10.1.2 Manifold or Analytical Cartridge.
acid (H PO ), 10 g of sulfanilamide, and 0.5 g of N-1-
3 4
10.1.3 Colorimeter equipped with a 15- or 50-mm tubular
(naphthyl)ethylenediamine dihydrochloride. Stir until dis-
flow cell and 540 6 10-nm filters.
solved. Add 1 mL of wetting agent, and dilute to 1 L with
10.1.4 Recorder or Electronic Data Acquisition Device.
water. This solution is stable for about a month when stored in
10.1.5 Digital Printer (Optional).
a brown bottle in a dark cool place.
10.1.6 Continuous Filter (Optional).
A 30 % aqueous solution of Brij 35, a polyoxyethylene compound with
The apparatus described is commercially available. ASTM does not undertake dodecyl alcohol (sp gr 1.18 to 1.22) has been found satisfactory for this purpose.
to ensure anyone utilizing an automated analysis system against liability of Different sizes of granulated cadmium may be used. The analyst should ensure
infringement of patent or assume such liability. that adequate reduction occurs with the size chosen.
´1
D3867 − 16 (2021)
FIG. 2 Nitrite-Nitrate Cartridge
NOTE 2—Potassium nitrite is easily oxidized, so use only fresh bottles
11.4 Copper Sulfate Solution (20 g/L)—Dissolve 20 g of
of this reagent.
copper sulfate pentahydrate (CuSO ·5H O) in 500 mL of
4 2
water. Dilute to 1 L. 11.10 Nitrite Solution, Standard (1.0 mL = 0.01 mg
NO –N)—Dilute 10 mL of stock nitrite solution (11.9)to1L
11.5 n-Hexane.
with water. This solution is unstable; prepare fresh as needed.
11.6 Hydrochloric Acid (1+1)—Slowly add 50 mL of
11.11 Filter Paper—Purchase suitable filter paper.Typically
concentrated hydrochloric acid (HCl) to 40 to 45 mL of water
the filter papers have a pore size of 0.45-µm membrane.
and dilute to 100 mL.
Material such as fine-textured, acid-washed, ashless paper, or
11.7 Nitrate Solution, Stock (1.0 mL = 1.0 mg NO -N)—
glass fiber paper are acceptable. The user must first ascertain
Dry potassium nitrate (KNO ) in an oven at 105°C for 24 h.
that the filter paper is of sufficient purity to use without
Dissolve 7.218 g in water in a 1-L volumetric flask. Dilute to
adversely affecting the bias and precision of the test method.
the mark with water. This solution is stable for up to 1 month
withrefrigeration.Iflongerstabilityisrequiredorrefrigeration
12. Preparation of Reduction Column
is not available, add 2 mL of chloroform as a preservative and
12.1 Cadmium Granules Treatment—Clean and copperize
store in a dark bottle. This solution is stable for 6 months. (See
new or used cadmium granules in the following manner:
8.2.)Alternatively,certifiednitratestocksolutionsarecommer-
12.1.1 Clean about 10 g of cadmium granules (11.2)by
cially available through chemical supply vendors and may be
used. washing with dilute HCl (11.6) and rinsing with water.
12.1.2 Swirl the clean cadmium in 100-mL portions of
11.8 Nitrate Solution, Standard (1.0 mL = 0.01 mg NO -
copper sulfate solution (11.4) in a beaker for 5 min or until the
N)—Dilute 10 mL of stock nitrate solution (11.7) to 1 L with
blue color partially fades. Decant and repeat with fresh copper
water and store in a dark bottle. Prepare fresh as needed.
sulfate until the first visible brown colloidal precipitate ap-
11.9 Nitrite Solution, Stock (1.0 mL = 1.0 mg NO -N)—
pears.
Place about7gof potassium nitrite (KNO ) in a tared 125-mL
12.1.3 Wash the granules with water at least 10 times to
beaker and dry for about 24 h to a constant weight in a
remove all of the precipitated copper.
desiccator containing a suitable desiccant.Adjust the weight of
12.2 Filling the Reduction Column:
the dry potassium nitrite to 6.072 g.Add 50 mLof water to the
12.2.1 Insert a small plug of glass wool in one end of the
beaker, stir until dissolved, and transfer quantitatively to a
column (10.2).
1000-mL volumetric flask. Dilute to the mark with water store
12.2.2 Fill the column with water to prevent the entrapment
in a sterilized bottle under refrigeration. Prepare fresh as
of air bubbles during the filling operation.
needed.Alternatively, certified nitrite stock solutions are com-
mercially available through chemical supply vendors and may 12.2.3 Fill the column with copper-cadmium granules, tap
be used. to pack the granules, and plug the open end with glass wool.
´1
D3867 − 16 (2021)
TABLE 1 Concentration of Calibration Standards, Automated
an integral part of the system to remove particulate matter.
Cadmium Reduction
Centrifugation can be used as an option.
NO -N or NO -N, mg/L mL Standard Solution/100 mL
3 2 14.1.2 For oil and grease removal, if necessary after
0.01 0.1
filtration, adjust the pH of the sample to 2 with concentrated
0.02 0.2
HCl. Extract with two 25-mL portions of n-hexane (11.5)ina
0.04 0.4
separatory funnel. Discard the n-hexane layer after each
0.1 1.0
0.2 2.0
extraction. Alternatively, solid-phase extraction filters may be
0.4 4.0
used.
0.7 7.0
14.1.3 For pH adjustment, determine the pH of the sample
1.0 10.0
with a pH meter. Adjust the pH to within the range from 6 to
8 with concentrated HCl or concentrated NH OH, if needed.
14.1.4 For correction for color interferences, if there is a
possibility that the color of the sample might absorb in the
12.3 Installation of Reduction Column—Install the copper-
photometric range from 530 6 10 nm, determine the back-
cadmium reduction column in the automatic analyzer system.
ground absorbance. Replace the color reagent (11.3) with a
Purge the system with ammonium chloride solution (11.1)
similar reagent where just the N-1-(naphthyl) ethylenediamine
using water in the sample line. Observe the following precau-
dihydrochloride is omitted and analyze the sample for back-
tions while installing the reduction column:
ground color absorbance as directed in the following proce-
12.3.1 Place the column in the manifold system in an
dure. Repeat the analysis using the complete color reagent.
upflow 20° incline to minimize channeling (see Fig. 1).
12.3.2 Fill all pump tubes with reagents before inserting the 14.2 Depending on the model of analysis system available,
column in the cartridge system to prevent the entrapment of air
set up the manifold and complete the system as shown in Fig.
bubbles. 1 or Fig. 2.
12.4 Reduction Column Storage—When it is not in use, put
NOTE 5—When determining nitrite alone, omit the reduction column
the sample line in water and purge the column with ammonium from the manifold system.
chloride solution (11.1) and water.
14.3 Turn on the colorimeter and the recorder and allow
them both to warm up for 30 min.
NOTE 3—Do not allow air to enter the column and do not let the
cadmium granules become dry. If this occurs, refill the column with
14.4 Obtain a stable baseline with all reagents (11.1 and
freshly treated cadmium granules.
11.3), feeding water through the sample line.
13. Calibration 14.5 Place the appropriate nitrate and nitrite calibration
standardsinthesamplerinorderofdecreasingconcentrationof
13.1 Using the standard nitrate solution (11.8) prepare
nitrogen. Fill the remainder of the sample tray with unknown
calibration standards by pipetting specified volumes of the
samples.
standard solution into 100-mLvolumetric flasks and diluting to
themarkwithwater.Table1specifiesthemillilitresofstandard 14.6 Forthemanifoldsystem,sampleatarateof30/h,1 + 1
cam. For the cartridge system, use a 40/h, 4 + 1 cam and a
solution required.
common wash.
13.2 Prepare at least one calibration standard from the
14.7 Switch the sample line from water to sampler and
standard nitrite solution (11.10) at the same concentration as
one of the nitrate standards to verify the efficiency of the begin the analysis, continuing until all unknowns have been
analyzed.
reduction column. Repeat this when a suspected loss in NO -N
reduction is observed.
15. Calculation
NOTE 4—When the sample to be analyzed is a saline water, use
15.1 Determine the concentration of nitrate or nitrite nitro-
substitute ocean water (SOW) to prepare the standards (Practice D1141).
gen in the samples in milligrams per litre by comparing the
Run a reagent water blank in addition to a SOW blank because the
peak heights of the samples with the standard curves (13.4)
reagentsusedtoprepareSOWfrequentlycontainnitriteornitrate,orboth.
Adjust this curve for the contaminant level in SOW.
manually or by a computer-based data handler.
13.3 Develop the color and determine the absorbance of
NOTE 6—If the background color absorbance has been measured
each standard as directed in the procedure (14.5).
(14.1.4), calculate the net absorbance by subtracting the background
absorbance from the measured absorbance of the color developed sample.
13.4 Use a direct reading instrument or prepare a standard
Use the net absorbance to determine the concentration of nitrogen in the
curvebyplottingthepeakheightsofeachprocessedcalibration
sample.
standard against its known concentrations.
15.2 Where separate values are required for nitrite-nitrogen
and nitrate-nitrogen, calculate the nitrate-nitrogen by subtract-
14. Procedure
ing the nitrite-nitrogen from the total nitrate-nitrite nitrogen
14.1 Removal of Interferences—Remove interferences (Sec-
content.
tion 6) by the following procedures:
16. Report
14.1.1 For turbidity removal, when suspended solids are
present, filter the sample through a glass-fiber filter or a 16.1 Report the following information:
0.45-µm filter. Alternatively, use a continuous filter (11.11)as 16.1.1 Report the nitrogen content in milligrams per litre as:
´1
D3867 − 16 (2021)
TABLE 2 Interlaboratory Precision for Nitrite Found in Selected TABLE 3 Reagent Water, Automated Cadmium Reduction
Matrices
Amount Amount Statistically
Radical Added, Found, Bias, % Significant
Water Matrix:
mg/L mg/L 95 % Level
Concentration (x),mg/L 0.05 0.09 0.42 0.80
S 0.024 0.006 0.033 0.049
T Nitrite-nitrogen 0.050 0.042 −16 no
S 0.012 0.005 0.029 0.043
O
0.090 0.096 + 6 yes
0.420 0.416 −1 no
Reagent Water:
0.800 0.798 0 no
Concentration (x), mg ⁄L 0.05 0.09 0.42 0.80
S 0.021 0.005 0.019 0.032
T Nitrate-nitrogen 0.050 0.044 −11 no
S 0.009 0.002 0.011 0.006
O
0.090 0.092 + 2 no
0.420 0.404 −4 yes
0.850 0.828 −3 no
Water Matrix
Amount Amount Statistically
Radical Added, Found, Bias, % Significant
mg/L mg/L 95 % Level
16.1.1.1 Nitrite-Nitrogen (NO -N), mg/L,
Nitrite-nitrogen 0.050 0.060 + 20 no
16.1.1.2 Nitrate-Nitrogen (NO -N), mg/L, and
0.090 0.097 + 8 yes
16.1.1.3 Combined Nitrate-Nitrite Nitrogen (NO,NO -N),
0.420 0.427 + 2 no
3 2
0.800 0.790 −1 no
mg/L.
Nitrate-nitrogen 0.050 0.053 + 6 no
17. Precision and Bias 0.090 0.081 −10 no
0.420 0.396 −6 yes
17.1 Precision Statement:
0.850 0.828 −3 no
17.1.1 Nitrite—Based on the results of six operators in five
laboratories, the overall and single-operator precision of this
test method for nitrite within its designated range for reagent
18.2.1 Analyze at least four working standards containing
water and selected water matrices (including surface, saline,
concentrations of nitrite-nitrate in water that bracket the
waste, and ground waters) varies with the quantity being tested
expected sample concentration prior to analysis of samples to
in accordance with Table 2. No data were rejected as outliers
calibrate the instrument.
for this statistical evaluation.
18.2.2 Verify instrument calibration after standardization by
17.1.2 Nitrate—The precision of this test method for nitrate
analyzing a standard at the concentration of one of the
withinitsdesignatedrangeforreagentwaterandselectedwater
calibration standards. The absorbance shall fall within 4 % of
matricesmaybeexpressedasfollows(concentrationsaregiven
the absorbance from the calibration. Alternately, the concen-
in mg/L):
trationofamid-rangestandardshouldfallwithin 615%ofthe
Reagent Water S = 0.0400
T
known concentration. Analyze a calibration blank to verify
S = 0.0296
O
system cleanliness.
Water Matrix S = 0.0437
T
S = 0.0300
O 18.2.3 If calibration cannot be verified, recalibrate the
instrument.
17.2 Precision and bias for this test method conform to
18.2.4 It is recommended to analyze a continuing calibra-
Practice D2777 – 77, which was in place at the time of
tion blank (CCB) and continuing calibration verification
collaborative testing. Under the allowances made in 1.4 of
(CCV) at a 10 % frequency. The results should fall within the
D2777 – 13, these precision and bias data do meet existing
expected precision of the method or 615 % of the known
requirements for interlaboratory studies of Committee D19 test
concentration.
methods.
18.3 Initial Demonstration of Laboratory Capability:
17.3 Bias Statement—Recoveries of known amounts of
18.3.1 If a laboratory has not performed the test before, or if
nitrites-nitrates from reagent water and selected water matrices
there has been a major change in the measurement system, for
are shown in Table 3.
example,newanalyst,newinstrument,andsoforth,aprecision
17.4 It is the user’s responsibility to ensure the validity of
and bias study must be performed to demonstrate laboratory
this test method for waters of untested matrices.
capability.
18.3.2 Analyze seven replicates of a standard solution
18. Quality Control
prepared from an Independent Reference Material containing a
18.1 In order to be certain that analytical values obtained
mid-range concentration of nitr
...