ASTM D3590-17

Standard Test Methods for Total Kjeldahl Nitrogen in Water

SIGNIFICANCE AND USE
4.1 These test methods are useful for measuring organic nitrogen and ammoniacal nitrogen, which are essential growth nutrients.  
4.2 Nitrogen compounds are widely distributed in the environment. Sources of nitrogen include surface-applied fertilizers, cleaning products, and drinking water treatment aids. Because nitrogen is a nutrient for photosynthetic organisms, it may be important to monitor and control discharge into the environment.
SCOPE
1.1 These test methods cover the determination of total Kjeldahl nitrogen. Section 24 on Quality Control pertains to these test methods. The following test methods are included:    
Sections  
Test Method A—Manual Digestion/Distillation  
8 – 14  
Test Method B—Semiautomated Colorimetric Bertholt  
15 – 23  
1.2 The analyst should be aware that precision and bias statements included may not necessarily apply to the water being tested.  
1.3 The values stated in SI units are to be regarded as 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 and health practices and determine the applicability of regulatory limitations prior to use.  
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-May-2017
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Replaces: ASTM D3590-11 - Standard Test Methods for Total Kjeldahl Nitrogen in Water
• Effective Date: 01-Jun-2017
• 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 D3370-08 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Oct-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 D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-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 D5810-96(2006) - Standard Guide for Spiking into Aqueous Samples
• Effective Date: 15-Aug-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1129-06 - Standard Terminology Relating to Water
• Effective Date: 15-Feb-2006

Overview

ASTM D3590-17: Standard Test Methods for Total Kjeldahl Nitrogen in Water provides procedures for determining the concentration of total Kjeldahl nitrogen (TKN)-the sum of organic nitrogen and ammoniacal nitrogen-in various water sources. Monitoring total Kjeldahl nitrogen is essential for environmental protection, water quality assessment, regulatory compliance, and wastewater management. This standard outlines both manual and semiautomated methods for accurate and reproducible TKN measurements.

Total Kjeldahl nitrogen is a key indicator of water quality. Nitrogen compounds, which originate from fertilizers, cleaning agents, and water treatment processes, are widely present in the environment. Analyzing TKN is crucial because elevated nitrogen levels can stimulate algal growth, impact drinking water safety, and contribute to environmental degradation.

Key Topics

• Significance of TKN Analysis: TKN measurements help determine organic and ammonia nitrogen, both of which are vital growth nutrients and indicators of pollution.
• Sample Collection and Preservation: Proper techniques for sample collection and handling are emphasized to ensure reliable results.
• Test Methods: The standard describes two primary methods:
  • Test Method A (Manual Digestion/Distillation): Involves acid digestion of samples, followed by distillation and quantification through titrimetric, colorimetric, or potentiometric analysis.
  • Test Method B (Semiautomated Colorimetric Berthelot Method): Automates digestion and employs a colorimetric reaction for nitrogen detection suitable for laboratories handling multiple samples.
• Interference and Quality Control: The standard discusses potential interferences (such as high nitrate or ammonia contamination) and stresses the need for rigorous quality control, including calibration, blanks, and matrix spikes, to maintain analytical accuracy.
• Data Quality and Reporting: Emphasis is placed on conducting duplicate analyses, using certified reference materials, and adhering to reporting protocols for traceable, auditable results.

Applications

ASTM D3590-17 is widely used across sectors requiring water quality monitoring and management, including:

• Drinking Water Production: Ensures compliance with regulatory nitrogen limits and helps safeguard public health.
• Wastewater Treatment Facilities: Assists in monitoring effluent to limit nutrient pollution and maintain compliance with discharge permits.
• Environmental Monitoring: Used to assess the nitrogen load in surface waters, such as rivers and lakes, to prevent eutrophication and the proliferation of harmful algal blooms.
• Industrial Water Management: Provides data for optimizing water reuse, managing process streams, and minimizing environmental impact from industrial effluents.
• Agricultural Runoff Monitoring: Offers a basis for evaluating the effectiveness of best management practices in controlling fertilizer-related water pollution.
• Research Laboratories: Supports academic and government research involving nutrient cycles, ecosystem health, and pollutant tracking.

Related Standards

• ASTM D1426: Test Methods for Ammonia Nitrogen in Water
• ASTM D1129: Terminology Relating to Water
• ASTM D1193: Specification for Reagent Water
• ASTM D2777: Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• ASTM D3370: Practices for Sampling Water from Closed Conduits
• ASTM D5810: Guide for Spiking into Aqueous Samples
• ASTM D5847: Practice for Writing Quality Control Specifications for Water Analysis
• EPA Methods: Various EPA-approved methods for nitrogen compounds in water analyses

Practical Value

Implementing ASTM D3590-17 helps organizations and laboratories meet regulatory requirements for nitrogen parameters, supports effective nutrient management strategies, and enables informed decision-making in water treatment and environmental stewardship. By following this standard, users ensure high data integrity, reproducibility, and comparability in total Kjeldahl nitrogen analysis-fundamental components of modern water quality management.

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.
Designation: D3590 − 17
Standard Test Methods for
Total Kjeldahl Nitrogen in Water
This standard is issued under the fixed designation D3590; 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.
1. Scope* D5847 Practice for Writing Quality Control Specifications
for Standard Test Methods for Water Analysis
1.1 These test methods cover the determination of total
Kjeldahl nitrogen. Section 24 on Quality Control pertains to
3. Terminology
these test methods. The following test methods are included:
3.1 Definitions:
Sections
Test Method A—Manual Digestion/Distillation 8–14 3.1.1 For definitions of terms used in this standard, refer to
Test Method B—Semiautomated Colorimetric Bertholt 15–23
Terminology D1129.
1.2 The analyst should be aware that precision and bias
3.2 Definitions of Terms Specific to This Standard:
statements included may not necessarily apply to the water
3.2.1 continuing calibration blank, n—a solution containing
being tested.
no analytes (of interest) which is used to verify blank response
1.3 The values stated in SI units are to be regarded as
and freedom from carryover.
standard. No other units of measurement are included in this
3.2.2 continuing calibration verification, n—a solution (or
standard.
setofsolutions)ofknownconcentrationusedtoverifyfreedom
1.4 This standard does not purport to address all of the from excessive instrumental drift; the concentration is to cover
safety concerns, if any, associated with its use. It is the
the range of calibration curve.
responsibility of the user of this standard to establish appro-
3.2.3 total Kjeldahl nitrogen, n—the sum of the nitrogen
priate safety and health practices and determine the applica-
contained in the free ammonia and other nitrogen compounds,
bility of regulatory limitations prior to use.
which are converted to ammonium sulfate [(NH ) SO ] under
4 2 4
1.5 This international standard was developed in accor-
the specified digestion conditions.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
4. Significance and Use
Development of International Standards, Guides and Recom-
4.1 These test methods are useful for measuring organic
mendations issued by the World Trade Organization Technical
nitrogen and ammoniacal nitrogen, which are essential growth
Barriers to Trade (TBT) Committee.
nutrients.
2. Referenced Documents
4.2 Nitrogen compounds are widely distributed in the envi-
ronment. Sources of nitrogen include surface-applied
2.1 ASTM Standards:
fertilizers, cleaning products, and drinking water treatment
D1129 Terminology Relating to Water
aids. Because nitrogen is a nutrient for photosynthetic
D1193 Specification for Reagent Water
organisms, it may be important to monitor and control dis-
D1426 Test Methods for Ammonia Nitrogen In Water
charge into the environment.
D2777 Practice for Determination of Precision and Bias of
Applicable Test Methods of Committee D19 on Water
5. Interferences
D3370 Practices for Sampling Water from Closed Conduits
D5810 Guide for Spiking into Aqueous Samples
5.1 Nitrateisknowntocauseaseriousnegativeinterference
in the test. Reportedly, a concentration of 250 mg/L NO
resultsinzerorecoveryofsomelevelofmg/LNaddedassome
These test methods are under the jurisdiction of ASTM Committee D19 on
nitrogen compound.
Water and are the direct responsibility of Subcommittee D19.05 on Inorganic
Constituents in Water.
5.2 The analyst is cautioned that ammonia in the laboratory
Current edition approved June 1, 2017. Published June 2017. Originally
may easily become an interference in these test methods from
approved in 1977. Last previous edition approved in 2011 as D3590 – 11. DOI:
10.1520/D3590-17.
contamination of reagents, caps, or from the laboratory atmo-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
sphere. Care should be taken that ammonium hydroxide, either
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
as a reagent or as a cleaning substance, is not used in the same
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. room.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3590 − 17
6. Purity of Reagents The residue is cooled, diluted, and is treated and alkalized with
a hydroxide-thiosulfate solution. The ammonia is distilled into
6.1 Reagent-grade chemicals shall be used in all tests.
a boric acid solution and total Kjeldahl nitrogen is determined
Unless otherwise indicated, it is intended that all reagents shall
by colorimetry, titrimetry, or potentiometry.
conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such
10. Apparatus
specifications are available. Other grades may be used, pro-
10.1 Digestion Apparatus—A Kjeldahl digestion apparatus
vided it is first ascertained that the reagent is of sufficient high
with 800 to 1000-mLflasks and suction takeoff to remove SO
purity to permit its use without lessening the accuracy of the
fumes and water.
determination.
10.2 Distillation Apparatus —A macro Kjeldahl flask con-
6.2 Purity of Water—Unless otherwise indicated, reference
nected to a condenser and an adaptor so that the distillate can
to water shall be understood to mean reagent water conforming
be collected.
to Specification D1193, Type I. Other reagent water types may
be used provided it is first ascertained that the water is of 10.3 Spectrophotometer or Colorimeter, for use at 425 nm
sufficiently high purity to permit its use without adversely with a spectral band path of not more than 620 nm and a light
affecting the precision and bias of the test method. Type III path of 1 cm or longer.
water was specified at the time of round-robin testing of this
10.4 Electrometer (pH Meter), with expanded millivolt
test method.
scale, or a specific ion meter.
10.5 Ammonia Selective Electrode.
7. Sampling and Preservation
10.6 Magnet Stirrer, thermally insulated.
7.1 Collect the sample in accordance with applicable Prac-
tices D3370.
11. Reagents and Materials
7.2 Samples may be preserved up to 28 days by adding
11.1 Ammonia Solution Stock, (1.0 mL = 1.0 mg ammonia
concentrated sulfuric acid to adjust to pH 2 or less and store
nitrogen)—Dissolve 3.819 g of ammonium chloride (NH Cl)
between 2 and 6°C. The preserved sample should be analyzed
in water and dilute to 1 L in a volumetric flask with water.
as soon as possible; data on decomposition are not available.
11.2 Ammonia Solution, Standard (1.0 mL = 0.01 mg am-
TEST METHOD A—MANUAL DIGESTION/
monia nitrogen)—Dilute 10.0 mL of the stock solution (see
DISTILLATION
11.1) with water to 1 L in a volumetric flask.
8.1 This test method covers the determination of total
11.3 Boric Acid Solution (2 %)—Dissolve 20 g of boric acid
Kjeldahl nitrogen in water. It measures free ammonia or
(H BO ) in water and dilute to 1 L with water in a volumetric
3 3
ammonia formed from the conversion of nitrogen components
flask.
of biological origin such as amino acids and proteins.
11.4 Mercuric Sulfate Solution—Dissolve8gofred mercu-
However, the procedure may not convert the nitrogenous
ric oxide (HgO) in a mixture of 10 mLof sulfuric acid (H SO ,
2 4
compounds of some wastes to ammonia. Examples of such
sp gr 1.84) and 40 mLof water, and dilute solution to 100 mL.
compounds that may not be measured are nitro compounds,
(Warning—Mercury has been designated by many regulatory
hydrozones, oximes, nitrates, semicarbazones, pyridines, and
agenciesasahazardousmaterialthatcancauseseriousmedical
some refractory tertiary amines.
issues. Mercury, or its vapor, has been demonstrated to be
8.2 Three alternatives are described for the final determina-
hazardous to health and corrosive to materials. Caution should
tion of the ammonia: a titrimetric method, which is applicable
be taken when handling mercury and mercury containing
to concentrations above 1 mg/L N; a Nesslerization method,
products. See the applicable product Safety Data Sheet (SDS)
which is applicable to concentrations below 1 mg/L N; and a
for additional information. Users should be aware that selling
potentiometric method which is applicable to the range from
mercury and/or mercury containing products into your state or
0.04 to 1000 mg/L N.
country may be prohibited by law.)
8.3 This test method is described for micro and macro
NOTE 1—Alternate catalysts such as copper sulfate (CuSO ) may be
systems. Micro determination can be made on sample aliquots
used but it is the users responsibility to determine the validity of other
catalysts.
containing up to 10 mg of nitrogen.
11.5 Mixed Indicator Solution—Mix 2 volumes of 0.2 %
9. Summary of Test Method
methyl red in 95 % ethanol with 1 volume of 0.2 % methylene
9.1 The sample is heated in the presence of concentrated
blue in ethanol. Prepare fresh every 30 days.
H SO,K SO , and HgSO , and is digested until SO fumes
2 4 2 4 4 3
11.6 Methyl Purple Indicator Solution (1 g/L)—Dissolve
are obtained and the solution becomes colorless or pale yellow.
0.4 g of dimethyl-aminoazobenzene-o-carboxylic acid, sodium
Reagent Chemicals, American Chemical Society Specifications, American Micro Kjeldahl steam distillation apparatus is commercially available.
Chemical Society, Washington, DC. For suggestions on the testing of reagents not EIL Model 8002-2 of Electronics Instruments Ltd. (U. S. Representative:
listed by theAmerican Chemical Society, and the United States Pharmacopeia and Cambridge Instrument Co., 73 Spring St., Ossining, NY 10562) has been found
National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, satisfactory for this purpose. Also, Orion Model 95-12 has been found satisfactory
MD. for this purpose.
D3590 − 17
salt, in approximately 300 mL of water. To this solution add SO fumesaregivenoffandthesolutionturnscolorlessorpale
0.55 g of a water-soluble blue dyestuff, dissolve, and dilute to yellow. Continue heating for an additional 30 min. Cool the
1 L with water. This indicator is available commercially in a residue and add 300 mL of water. Mix well.
prepared form.
NOTE2—Digestingthesamplewithapacketand20mLofconcentrated
11.7 Nessler Reagent—Dissolve 100 g of mercuric iodide H SO is acceptable. Cut the end of the package and empty the contents
2 4
into the digestion flask.
(HgI ) and 70 g of potassium iodide (KI) in a small volume of
water. Add this mixture slowly, with stirring, to a cooled
12.2.3 Alkalize the digestate by careful addition of 100 mL
solution of 160 g of sodium hydroxide (NaOH) in 500 mL of
of sodium hydroxide-thiosulfate solution (see 11.11). Do not
water. Dilute the mixture to 1 L. This solution is stable for at
mix until the digestion flask has been connected to the
least one year if stored in a thick amber polyethylene bottle out
distillation apparatus (see 12.2.4).
of direct sunlight. (Warning—See 11.4.)
NOTE 3—Slow addition of the heavy caustic solution down the tilted
11.8 Phenolphthalein Indicator Solution—Dissolve5gof
neck of the digestion flask will cause the heavier solution to underlay the
phenolphthalein in 500 mL of 95 % ethyl alcohol or isopropa- aqueous H SO without loss of free ammonia.
2 4
nol and add 500 mL of water. Add NaOH (0.8 g/L) solution
12.2.4 Connect the Kjeldahl flask to the condenser with the
dropwise until a faint pink color appears.
tip of the condenser (or an extension of the condenser tip)
11.9 Sodium Hydroxide Solution (400 g/L)—Dissolve 400 g below the level of 50 mL of 2 % boric acid solution (see 11.3)
contained in a 500-mL Erlenmeyer flask. Distill 300 mL at the
ofNaOHin800mLofwater,cool,anddiluteto1Lwithwater.
rate of 6 to 10 mL/min.
11.10 Sodium Hydroxide Solution(0.8g/L)—Dilute2mLof
12.2.5 Transfer the distillate to a 500-mL volumetric flask,
NaOH solution (400 g/L) (see 11.9) with water to 1 L.
dilute to volume with water, and mix. Transfer 250 mL to an
11.11 Sodium Hydroxide-Sodium Thiosulfate Solution—
Erlenmeyer flask and titrate with H SO (see 12.4.1). If the
2 4
Dissolve 500 g of NaOH and 25 g of Na S O ·5H O in water
2 2 3 2
concentrationisfoundtobebelow1mg/L,determinethevalue
and dilute to 1 L.
colorimetrically. Use the remaining 250 mL for this determi-
11.12 SulfuricAcidSolution,Standard(0.02N,1mL = 0.28 nation.
mg ammonia nitrogen)—Prepare a stock solution of approxi-
12.3 Micro Kjeldahl System:
mately 0.1 N acid by diluting 3 mLof concentrated H SO (sp
2 4
12.3.1 Place 50.0 mL of sample or an aliquot in a 100-mL
gr 1.84) to 1 L with water. Dilute 200 mL of this solution to 1
Kjeldahl flask and add 10 mLof digestion solution (see 11.13).
L with water. Standardize the approximately 0.02 N H SO
2 4
At the same time start a reagent blank. Evaporate the mixture
solution against 0.0200 N Na CO solution. This last solution
2 3
in the Kjeldahl apparatus until SO fumes are given off and the
is prepared by dissolving 1.060 g of anhydrous Na CO , oven
2 3
solution turns colorless or pale yellow. Digest for an additional
dried at 140°C, and diluting to 1 L with water.
30 min. Cool the residue and add 30 mL of water.
11.13 DigestionSolution—Dissolve267gofK SO in1300
2 4 12.3.2 Alkalizethedigestatebycarefuladditionof10mLof
mL water and 400 mL of concentrated H SO . Add 50 mL of
2 4
sodium hydroxide-thiosulfate solution (see 11.11). Do not mix
mercuric sulfate solution (see 11.4) and dilute to 2 L with
until the digestion flask has been connected to the distillation
water.Adigestion packet may be used in place of the digestion
apparatus (see Note 3).
solution in the macro Kjeldahl system.
12.3.3 Connect the Kjeldahl flask to the condenser with the
tip of the condenser (or an extension of the condenser tip)
12. Procedure
below the level of 5 mL of 2 % H BO solution (see 11.3)
3 3
12.1 Clean the distillation apparatus with steam before use contained in a small Erlenmeyer flask. Distill 30 mLat the rate
by distilling a 1 + 1 mixture of water and sodium hydroxide- of 6 to 10 mL/min.
thiosulfate solution (see 11.11) until the distillate is ammonia-
12.3.4 Transfer to a 50-mL volumetric flask, dilute to
free. Repeat this operation each time the apparatus is out of
volume with water, and mix. Pipet 25 mL to an Erlenmeyer
service long enough to accumulate ammonia (usually4hor
flask and titrate with H SO (see 12.4.1). If the concentration
2 4
more).
is found to be below 1 mg/L determine the value colorimetri-
cally. Use 20 mL of the remaining solution for this determina-
12.2 Macro Kjeldahl System:
tion.
12.2.1 Place a measured sample into an 800-mL Kjeldahl
flask and dilute to 500 mL. The sample size can be determined
12.4 Determination of Ammonia Distillate—Determine the
using the following table:
ammonia content of the distillate titrimetrically,
Kjeldahl Nitrogen in Sample, Sample Size, colorimetrically, or potentiometrically.
mg/L mL
12.4.1 Titrimetric Determination—Add 3 drops of the
0to5 500
mixed indicator (see 11.5) to the distillate and titrate the
5to10 250
10 to 20 100
ammonia with 0.02 N H SO (see 11.12), matching the end
2 4
20 to 50 50.0
point against a blank containing the same volume of water and
50 to 500 25.0
H BO solution (see 11.3). If a pH meter is preferred, titrate to
3 3
Prepare a 500-mL reagent water blank.
pH 6.2.
12.2.2 Add 100 mL of digestion solution (see 11.13) (see
Note 2) and digest the mixture in the Kjeldahl apparatus until NOTE 4—As an alternative, 2 drops of methyl purple indicator solution
D3590 − 17
(see 11.6) may be used and the titration carried out to the intermediate
total Kjeldahl nitrogen, mg/L 5 E 31000/S 3D/C (3)
gray end point.
where:
12.4.2 Colorimetric Determination (Samples)—To a 20-mL
1000 = 1000 mL/L,
aliquot from the macro procedure (see 12.2.5) or micro
E =NH -H read from curve, corrected for blank, mg,
procedure (see 12.3.4) diluted to 50 mL, add 1 mL of Nessler
D = final adjusted distillate volume, mL,
reagent (see 11.7), and mix.After 20 min, read the absorbance
C = distillate taken for Nesslerization, mL, and
at 425 nm against the blank using 1-cm cells. Read the
S = sample digested, mL.
ammonia nitrogen in milligrams for the samples from the
13.3 If the potentiometric determination is used, calculate
standard curve.
the total Kjeldahl nitrogen in the original sample using Eq 4:
12.4.2.1 Calibration Curve—Prepare a series of standards
on a daily basis in 50-mL volumetric flasks and dilute as total Kjeldahl nitrogen, mg/L 5 E 31000/S 3D/C (4)
follows:
where:
Millilitres of Standard (see 11.2)1.0 Milligrams of NH -N/50.0
E =NH -N/L as determined using Test Method B of Test
mL=0.01mgNH -N mL 3
0.0 0.0 Methods D1426,
0.5 0.005
S = sample digested, mL,
1.0 0.010
D = final adjusted volume, mL, and
2.0 0.020
C = distillate taken for measurement, mL.
4.0 0.040
5.0 0.050
8.0 0.080
14. Precision and Bias
10.0 0.10
14.1 Thirty-oneanalystsin20laboratoriesusedtitrationand
To the standards diluted to 50 mL add 1 mL of Nessler
Nesslerization to analyze natural water samples containing
reagent (see 11.7) and mix. After 20 min read the absorbance
exact increments of organic nitrogen and obtained the follow-
at 425 nm against the blank using 1-cm cells. From the values
ing results:
obtained for the standards plot a standard curve of absorbance
Amount Added as Amount Found as Precision as
versus milligrams of NH -N.
3 Bias,
Nitrogen, Kjeldahl, Nitrogen, Kjeldahl, Standard Deviation,
%
12.4.3 Potentiometric Determination—Test Method B of
mg/L N mg/L N mg/L N
Test Methods D1426 should be used for this determination. 0.20 0.23 0.197 +15.54
0.31 0.33 0.247 +5.45
12.4.3.1 It is recommended that at least two standards (a
4.10 4.14 1.056 +1.03
high and a low) be digested, distilled, and compared to similar
4.61 4.53 1.191 −1.67
values on the calibration curve to ensure that the digestion-
14.2 The potentiometric test method has not been validated
distillation technique is reliable. If treated standards do not
in conjunction with the digestion-distillation procedure de-
agree with untreated standards, the operator should find the
scribedinthisstandard.However,sincetheprocedureprovides
cause of the apparent error before proceeding.
a relatively clean sample, it is thought that the user may be
guided by the precision and bias information presented in Test
13. Calculation
Method B of Test Methods D1426 and by 12.4.3 of this test
13.1 If the titrimetric procedure is used, calculate the total method.
Kjeldahl nitrogen in the original sample using Eq 1:
14.3 The data in Section 14 may not apply to types of water
total Kjeldahl nitrogen, mg/L (1)
other than those tested. It is the responsibility of the analyst to
ensure the validity of this test method for untested matrices.
5 A 2 B N 3F 31000/S 3D/C
~ !
14.4 Precision and bias for this test method conforms to
where:
Practice D2777 – 77, which was in place at the time of
collaborative testing. Under the allowances made in 1.4 of
1000 = 1000 mL/L,
A = standard 0.02 N H SO solution used in titrating
Practice D2777 – 13, these precision and bias data do meet
2 4
sample, mL, existing requirements for interlaboratory studies of Committee
B = standard 0.02 N H SO solution used in titrating
D19 test methods.
2 4
blank, mL,
TEST METHOD B—SEMIAUTOMATED
N = normality of H SO solution,
2 4
COLORIMETRIC BERTHELOT
F = milliequivalent weight of nitrogen (14 mg),
S = sample digested, mL,
15.1 This test method covers the automated determination
C = distillate taken for titration, mL, and
of total Kjeldahl nitrogen in water and wastewater and is based
D = final adjusted distillate volume, mL.
If the H SO is exactly 0.0200 N and exactly one half of the
2 4
distillate is taken for measurement, the equation is shortened, Supporting data have been filed at ASTM International Headquarters and may
beobtainedbyrequestingResearchReportRR:D19-1041.ContactASTMCustomer
as shown in Eq 2
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D3590 − 11 D3590 − 17
Standard Test Methods for
Total Kjeldahl Nitrogen in Water
This standard is issued under the fixed designation D3590; 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.
1. Scope*
1.1 These test methods cover the determination of total Kjeldahl nitrogen. Section 24 on Quality Control pertains to these test
methods. The following test methods are included:
Sections
Test Method A—Manual Digestion/Distillation 8 – 13
Test Method A—Manual Digestion/Distillation 8 – 14
Test Method B—Semiautomated Colorimetric Bertholt 15 – 22
Test Method B—Semiautomated Colorimetric Bertholt 15 – 23
1.2 The analyst should be aware that precision and bias statements included may not necessarily apply to the water being tested.
1.3 The values stated in SI units are to be regarded as 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 and health practices and determine the applicability of regulatory
limitations prior to use.
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.
2. Referenced Documents
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
D1426 Test Methods for Ammonia Nitrogen In Water
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D3370 Practices for Sampling Water from Closed Conduits
D5810 Guide for Spiking into Aqueous Samples
D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis
3. Terminology
3.1 Definitions—Definitions: For definitions of terms used in these test methods, refer to Terminology D1129.
3.1.1 For definitions of terms used in this standard, refer to Terminology D1129.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 continuing calibration blank, n—a solution containing no analytes (of interest) which is used to verify blank response and
freedom from carryover.
3.2.2 continuing calibration verification, n—a solution (or set of solutions) of known concentration used to verify freedom from
excessive instrumental drift; the concentration is to cover the range of calibration curve.
3.2.3 total Kjeldahl nitrogen, n—the sum of the nitrogen contained in the free ammonia and other nitrogen compounds, which
are converted to ammonium sulfate [(NH ) SO ] under the specified digestion conditions.
4 2 4
These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituents
in Water.
Current edition approved April 1, 2011June 1, 2017. Published April 2011June 2017. Originally approved in 1977. Last previous edition approved in 20062011 as
D3590 – 02 (2006).D3590 – 11. DOI: 10.1520/D3590-11.10.1520/D3590-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3590 − 17
4. Significance and Use
4.1 These test methods are useful for measuring organic nitrogen and ammoniacal nitrogen, which are essential growth
nutrients.
4.2 Nitrogen compounds are widely distributed in the environment. Sources of nitrogen include surface-applied fertilizers,
cleaning products, and drinking water treatment aids. Because nitrogen is a nutrient for photosynthetic organisms, it may be
important to monitor and control discharge into the environment.
5. Interferences
5.1 Nitrate is known to cause a serious negative interference in the test. Reportedly, a concentration of 250 mg/L NO results
in zero recovery of some level of mg/L N added as some Nnitrogen compound.
5.2 The analyst is cautioned that ammonia in the laboratory may easily become an interference in these test methods from
contamination of reagents, caps, or from the laboratory atmosphere. Care should be taken that ammonium hydroxide, either as a
reagent or as a cleaning substance, is not used in the same room.
6. Purity of Reagents
6.1 Reagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform
to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are
available. Other grades may be used, provided it is first ascertained that the reagent is of sufficient high purity to permit its use
without lessening the accuracy of the determination.
6.2 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to
Specification D1193, Type I. Other reagent water types may be used provided it is first ascertained that the water is of sufficiently
high purity to permit its use without adversely affecting the precision and bias of the test method. Type III water was specified at
the time of round-robin testing of this test method.
7. Sampling and Preservation
7.1 Collect the sample in accordance with applicable Practices D3370.
7.2 Samples may be preserved up to 28 days by adding concentrated sulfuric acid to adjust to pH 2 or less and storing atstore
between 2 –and 6°C. The preserved sample should be analyzed as soon as possible; data on decomposition are not available.
TEST METHOD A—MANUAL DIGESTION/DISTILLATION
8. Scope
8.1 This test method covers the determination of total Kjeldahl nitrogen in water. It measures free ammonia or ammonia formed
from the conversion of nitrogen components of biological origin such as amino acids and proteins. However, the procedure may
not convert the nitrogenous compounds of some wastes to ammonia. Examples of such compounds that may not be measured are
nitro compounds, hydrozones, oximes, nitrates, semicarbazones, pyridines, and some refractory tertiary amines.
8.2 Three alternatives are described for the final determination of the ammonia: a titrimetric method, which is applicable to
concentrations above 1 mg N/L; a Nesslerization method, which is applicable to concentrations below 1 mg N/L; and a
potentiometric method which is applicable to the range from 0.04 to 1000 mg N/L.
8.3 This test method is described for micro and macro systems. Micro determination can be made on sample aliquots containing
up to 10 mg of nitrogen.
8.1 This test method covers the determination of total Kjeldahl nitrogen in water. It measures free ammonia or ammonia formed
from the conversion of nitrogen components of biological origin such as amino acids and proteins. However, the procedure may
not convert the nitrogenous compounds of some wastes to ammonia. Examples of such compounds that may not be measured are
nitro compounds, hydrozones, oximes, nitrates, semicarbazones, pyridines, and some refractory tertiary amines.
8.2 Three alternatives are described for the final determination of the ammonia: a titrimetric method, which is applicable to
concentrations above 1 mg/L N; a Nesslerization method, which is applicable to concentrations below 1 mg/L N; and a
potentiometric method which is applicable to the range from 0.04 to 1000 mg/L N.
8.3 This test method is described for micro and macro systems. Micro determination can be made on sample aliquots containing
up to 10 mg of nitrogen.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
D3590 − 17
9. Summary of Test Method
9.1 The sample is heated in the presence of concentrated H SO , K SO , and HgSO , and is digested until SO fumes are
2 4 2 4 4 3
obtained and the solution becomes colorless or pale yellow. The residue is cooled, diluted, and is treated and alkalized with a
hydroxide-thiosulfate solution. The ammonia is distilled into a boric acid solution and total Kjeldahl nitrogen is determined by
colorimetry, titrimetry, or potentiometry.
10. Apparatus
10.1 Digestion Apparatus—A Kjeldahl digestion apparatus with 800 to 100-mL1000-mL flasks and suction takeoff to remove
SO fumes and water.
10.2 Distillation Apparatus —A macro Kjeldahl flask connected to a condenser and an adaptor so that the distillate can be
collected.
10.3 Spectrophotometer or Colorimeter, for use at 425 nm with a spectral band path of not more than 6 20 620 nm and a light
path of 1 cm or longer.
10.4 Electrometer (pH Meter), with expanded millivolt scale, or a specific ion meter.
10.5 Ammonia Selective Electrode.
10.6 Magnet Stirrer, thermally insulated.
11. Reagents and Materials
11.1 Ammonia Solution Stock, (1.0 mL = 1.0 mg ammonia nitrogen)—Dissolve 3.819 g of ammonium chloride (NH Cl) in
water and dilute to 1 L in a volumetric flask with water.
11.2 Ammonia Solution, Standard (1.0 mL = 0.01 mg ammonia nitrogen)—Dilute 10.0 mL of the stock solution (see 11.1) with
water to 1 L in a volumetric flask.
11.3 Boric Acid Solution (2 %)—Dissolve 20 g of boric acid (H BO ) in water and dilute to 1 L with water in a volumetric flask.
3 3
11.4 Mercuric Sulfate Solution—Dissolve 8 g of red mercuric oxide (HgO) in a mixture of 10 mL of sulfuric acid (H SO , sp
2 4
gr 1.84) and 40 mL of water, and dilute solution to 100 mL. (Warning—Mercury has been designated by many regulatory agencies
as a hazardous material that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to
health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the
applicable product Safety Data Sheet (SDS) for additional information. Users should be aware that selling mercury and/or mercury
containing products into your state or country may be prohibited by law.)
NOTE 1—Mercury is a toxic metal and requiresAlternate catalysts such as copper sulfate (CuSO special diposal requirements. See Occupational Health
and Safety Act (OSHA) regulations for specific instructions on handling and disposal of mercury compounds. Alternate catalysts ) may be used but it
is the users responsibility to determine the validity of other catalysts.
11.5 Mixed Indicator Solution—Mix 2 volumes of 0.2 % methyl red in 95 % ethanol with 1 volume of 0.2 % methylene blue
in ethanol. Prepare fresh every 30 days.
11.6 Methyl Purple Indicator Solution (1 g/L)—Dissolve 0.4 g of dimethyl-aminoazobenzene-o-carboxylic acid, sodium salt, in
approximately 300 mL of water. To this solution add 0.55 g of a water-soluble blue dyestuff, Color Index No. 714,dissolve, and
dilute to 1 L with water. This indicator is available commercially in a prepared form.
11.7 Nessler Reagent—Dissolve 100 g of mercuric iodide (HgI ) and 70 g of potassium iodide (KI) in a small volume of water.
Add this mixture slowly, with stirring, to a cooled solution of 160 g of sodium hydroxide (NaOH) in 500 mL of water. Dilute the
mixture to 1 L. This solution is stable for at least one year if stored in a thick amber polyethylene bottle out of direct sunlight.
(Warning—See 11.4.)
NOTE 2—Mercury is a toxic metal and requires special diposal requirements. See Occupational Health and Safety Act (OSHA) regulations for specific
instructions on handling and disposal of mercury compounds. Alternate reagents may be used but it is the users responsibility to determine the validity
of other reagents.
11.8 Phenolphthalein Indicator Solution—Dissolve 5 g of phenolphthalein in 500 mL of 95 % ethyl alcohol or isopropanol and
add 500 mL of water. Add NaOH (0.8 g/L) solution dropwise until a faint pink color appears.
11.9 Sodium Hydroxide Solution (400 g/L)—Dissolve 400 g of NaOH in 800 mL of water, cool, and dilute to 1 L with water.
11.10 Sodium Hydroxide Solution (0.8 g/L)—Dilute 2 mL of NaOH solution (400 g/L) (see 11.9) with water to 1 L.
Micro Kjeldahl steam distillation apparatus is commercially available.
EIL Model 8002-2 of Electronics Instruments Ltd. (U. S. Representative: Cambridge Instrument Co., 73 Spring St., Ossining, NY 10562) has been found satisfactory
for this purpose. Also, Orion Model 95-12 has been found satisfactory for this purpose.
D3590 − 17
11.11 Sodium Hydroxide-Sodium Thiosulfate Solution—Dissolve 500 g of NaOH and 25 g of Na S O ·5H O in water and dilute
2 2 3 2
to 1 L.
11.12 Sulfuric Acid Solution, Standard (0.02 N, 1 mL = 0.28 mg ammonia nitrogen)—Prepare a stock solution of approximately
0.1 N acid by diluting 3 mL of concentrated H SO (sp gr 1.84) to 1 L with water. Dilute 200 mL of this solution to 1 L with water.
2 4
Standardize the approximately 0.02 N H SO solution against 0.0200 N Na CO solution. This last solution is prepared by
2 4 2 3
dissolving 1.060 g of anhydrous Na CO , oven dried at 140°C, and diluting to 1 L with water.
2 3
11.13 Digestion Solution—Dissolve 267 g of K SO in 1300 mL water and 400 mL of concentrated H SO . Add 50 mL of
2 4 2 4
mercuric sulfate solution (see 11.4) and dilute to 2 L with water. A digestion packet may be used in place of the digestion solution
in the macro Kjeldahl system.
12. Procedure
12.1 Clean the distillation apparatus with steam before use by distilling a 1 + 1 mixture of water and sodium hydroxide-
thiosulfate solution (see 11.11) until the distillate is ammonia-free. Repeat this operation each time the apparatus is out of service
long enough to accumulate ammonia (usually 4 h or more).
12.2 Macro Kjeldahl System:
12.2.1 Place a measured sample into an 800-mL Kjeldahl flask and dilute to 500 mL. The sample size can be determined using
the following table:
Kjeldahl Nitrogen in Sample, Sample Size,
mg/L mL
0 to 5 500
5 to 10 250
10 to 20 100
20 to 50 50.0
50 to 500 25.0
Prepare a 500-mL reagent water blank.
12.2.2 Add 100 mL of digestion solution (see 11.13) (see Note 32) and digest the mixture in the Kjeldahl apparatus until SO
fumes are given off and the solution turns colorless or pale yellow. Continue heating for an additional 30 min. Cool the residue
and add 300 mL of water. Mix well.
NOTE 2—Digesting the sample with a packet and 20 mL of concentrated H SO is acceptable. Cut the end of the package and empty the contents into
2 4
the digestion flask.
12.2.3 Alkalize the digestate by careful addition of 100 mL of sodium hydroxide-thiosulfate solution (see 11.11). Do not mix
until the digestion flask has been connected to the distillation apparatus (see 12.2.4).
NOTE 3—Slow addition of the heavy caustic solution down the tilted neck of the digestion flask will cause the heavier solution to underlay the aqueous
H SO without loss of free ammonia.
2 4
12.2.4 Connect the Kjeldahl flask to the condenser with the tip of the condenser (or an extension of the condenser tip) below
the level of 50 mL of 2 % boric acid solution (see 11.3) contained in a 500-mL Erlenmeyer flask. Distill 300 mL at the rate of 6
to 10 mL/min.
12.2.5 Transfer the distillate to a 500-mL volumetric flask, dilute to volume with water, and mix. Transfer 250 mL to an
Erlenmeyer flask and titrate with H SO (see 12.4.1). If the concentration is found to be below 1 mg/L, determine the value
2 4
colorimetrically. Use the remaining 250 mL for this determination.
12.3 Micro Kjeldahl System:
12.3.1 Place 50.0 mL of sample or an aliquot in a 100-mL Kjeldahl flask and add 10 mL of digestion solution (see 11.13). At
the same time start a reagent blank. Evaporate the mixture in the Kjeldahl apparatus until SO fumes are given off and the solution
turns colorless or pale yellow. Digest for an additional 30 min. Cool the residue and add 30 mL of water.
12.3.2 Alkalize the digestate by careful addition of 10 mL of sodium hydroxide-thiosulfate solution (see 11.11). Do not mix until
the digestion flask has been connected to the distillation apparatus (see Note 43).
12.3.3 Connect the Kjeldahl flask to the condenser with the tip of the condenser (or an extension of the condenser tip) below
the level of 5 mL of 2 % H BO solution (see 11.3) contained in a small Erlenmeyer flask. Distill 30 mL at the rate of 6 to 10
3 3
mL/min.
12.3.4 Transfer to a 50-mL volumetric flask, dilute to volume with water, and mix. Pipet 25 mL to an Erlenmeyer flask and
titrate with H SO (see 12.4.1). If the concentration is found to be below 1 mg/L determine the value colorimetrically. Use 20 mL
2 4
of the remaining solution for this determination.
12.4 Determination of Ammonia Distillate—Determine the ammonia content of the distillate titrimetrically, colorimetrically, or
potentiometrically.
12.4.1 Titrimetric Determination—Add 3 drops of the mixed indicator (see 11.5) to the distillate and titrate the ammonia with
0.02 N H SO (see 11.12), matching the end point against a blank containing the same volume of water and H BO solution (see
2 4 3 3
11.3). If a pH meter is preferred, titrate to pH 6.2.6.2.
D3590 − 17
NOTE 4—As an alternative, 2 drops of methyl purple indicator solution (see 11.6) may be used and the titration carried out to the intermediate gray
end point.
12.4.2 Colorimetric Determination (Samples)—To a 20-mL aliquot from the macro procedure (see 12.2.5) or micro procedure
(see 12.3.4) diluted to 50 mL, add 1 mL of Nessler reagent (see 11.7), and mix. After 20 min, read the absorbance at 425 nm against
the blank using 1-cm cells. Read the ammonia nitrogen in milligrams for the samples from the standard curve.
12.4.2.1 Calibration Curve—Prepare a series of standards on a daily basis in 50-mL volumetric flasks and dilute as follows:
Millilitres of Standard (see 11.2) 1.0 Milligrams of NH -N/50.0
mL = 0.01 mg NH -N mL
0.0 0.0
0.5 0.005
1.0 0.010
2.0 0.020
4.0 0.040
5.0 0.050
8.0 0.080
10.0 0.10
To the standards diluted to 50 mL add 1 mL of Nessler reagent (see 11.7) and mix. After 20 min read the absorbance at 425 nm
against the blank using 1-cm cells. From the values obtained for the standards plot a standard curve of absorbance versus
milligrams of NH -N.
12.4.3 Potentiometric Determination—Test Method B of Test Methods D1426 should be used for this determination.
12.4.3.1 It is recommended that at least two standards (a high and a low) be digested, distilled, and compared to similar values
on the calibration curve to ensure that the digestion-distillation technique is reliable. If treated standards do not agree with untreated
standards, the operator should find the cause of the apparent error before proceeding.
13. Calculation
13.1 If the titrimetric procedure is used, calculate the total Kjeldahl nitrogen in the original sample using Eq 1:
total Kjeldahl nitrogen, mg/L (1)
5 A 2 B N 3F 31000/S 3D/C
~ !
where:
1000 = 1000 mL/liter
1000 = 1000 mL/L,
A = standard 0.02 N H SO solution used in titrating sample, mL,
2 4
B = standard 0.02 N H SO solution used in titrating blank, mL,
2 4
N = normality of H SO solution,
2 4
F = milliequivalent weight of nitrogen (14 mg),
S = sample digested, mL,
C = distillate taken for titration, mL, and
D = final adjusted distillate volume, mL.
If the H SO is exactly 0.0200 N and exactly one half of the distillate is taken for measurement, the equation is shortened, as
2 4
shown in Eq 2:
total Kjeldahl nitrogen, mg/L5 ~A 2 B! 3560/S (2)
13.2 If the Nessler procedure is used, calculate the total Kjeldahl nitrogen in the original sample using Eq 3:
total Kjeldahl nitrogen, mg/L5 E 31000/S 3D/C (3)
where:
1000 = 1000 mL/liter
1000 = 1000 mL/L,
E = NH -H read from curve, corrected for blank, mg,
D = final adjusted distillate volume, mL,
C = distillate taken for Nesslerization, mL, and
S = sample digested, mL.
13.3 If the potentiometric determination is used, calculate the total Kjeldahl nitrogen in the original sample using Eq 4:
total Kjeldahl nitrogen, mg/L5 E 31000/S 3D/C (4)
where:
E = NH -N/L as determined using Test Method B of Test Methods D1426,
S = sample digested, mL,
D = final adjusted volume, mL, and
D3590 − 17
C = distillate taken for measurement, mL.
14. Precision and Bias
14.1 Thirty-one analysts in 20 laboratories used titration and Nesslerization to analyze natural water samples containing exact
increments of organic nitrogen and obtained the following results:
Amount Added Amount Found Precision as
as Nitrogen, as Nitrogen, Standard De-
Kjeldahl, Kjeldahl, viation, mg
mg N/L mg N/L N/L Bias, %
0.20 0.23 0.197 + 15.54
0.31 0.33 0.247 + 5.45
4.10 4.14 1.056 + 1.03
4.61 4.53 1.191 − 1.67
Amount Added as Amount Found as Precision as
Bias,
Nitrogen, Kjeldahl, Nitrogen, Kjeldahl, Standard Deviation,
%
mg/L N mg/L N mg/L N
0.20 0.23 0.197 +15.54
0.31 0.33 0.247 +5.45
4.10 4.14 1.056 +1.03
4.61 4.53 1.191 −1.67
14.2 The potentiometric test method has not been validated in conjunction with the digestion-distillation procedure described
in this standard. However, since the procedure provides a relatively clean sample, it is thought that the user may be guided by the
precision and bias information presented in Test Method B of Test Methods D1426 and by 12.4.3 of this test method.
14.3 The data in Section 14 may not apply to types of water other than those tested. It is the responsibility of the analyst to
ensure the validity of this test method for untested matrices.
14.4 Precision and bias for this test method conforms to Practice D2777 – 77, which was in place at the time of collaborative
testing. Under the allowances made in 1.4 of Practice D2777 – 08,13, these precision and bias data do meet existing requirements
for interlaboratory studies of Committee D19 test methods.
TEST METHOD B—SEMIAUTOMATED COLORIMETRIC BERTHELOT
15. Scope
15.1 This test method covers the automated determination of total Kjeldahl nitrogen in water and wastewater and is based on
the same principle and subject to the same limitations as the manual method (see 8.1).
15.2 This test method is a semiautomated procedu
...