ASTM D1426-15(2021)e1

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

• 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 D1066-18e1 - Standard Practice for Sampling Steam
• Effective Date: 01-Aug-2018
• Refers: ASTM D1066-18 - Standard Practice for Sampling Steam
• Effective Date: 01-Aug-2018
• 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 D1066-11 - Standard Practice for Sampling Steam
• Effective Date: 15-Jun-2011
• 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 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 D1066-06 - Standard Practice for Sampling Steam
• Effective Date: 15-Dec-2006
• 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

Overview

ASTM D1426-15(2021)e1, published by ASTM International, provides standardized test methods for the determination of ammonia nitrogen in water. Ammonia nitrogen is a critical parameter in water quality monitoring as it is a major nutrient and can also be toxic to aquatic organisms. This standard outlines two primary test methods-Direct Nesslerization and Ion Selective Electrode-applicable to various types of water, including surface, industrial, effluent, and demineralized water.

The standard supports efforts in environmental protection, regulatory compliance, and water management by defining clear, repeatable procedures for assessing ammonia levels. These methods play an essential role in routine monitoring, wastewater treatment, and environmental impact assessments.

Key Topics

• Nitrogen Forms in Water
  Water can contain nitrogen in several forms: ammonia, nitrate, nitrite, and organic nitrogen. The ASTM D1426 standard focuses on ammonia nitrogen, which exists both as a soluble gas (NH₃) and ammonium ion (NH₄⁺). The ratio depends on temperature and pH.

• Test Method A: Direct Nesslerization

  • Suited for routine testing of steam condensates and demineralizer effluents
  • Uses a colorimetric reaction to quantify ammonia
  • Best for samples with relatively low matrix complexity

• Test Method B: Ion Selective Electrode (ISE)

  • Designed for a broad range of reagent and effluent waters
  • Effective for ammonia concentrations from 0.5 to 1000 mg NH₃-N/L, with higher concentrations measurable by dilution
  • Recommended for applications requiring rapid, high-range, or automated ammonia nitrogen analysis

• Sample Handling and Preservation

  • Proper procedures for collecting and storing samples
  • Key to maintaining sample integrity and analytical accuracy

• Quality Control

  • Regular calibration, method blanks, laboratory control samples, matrix spikes, and duplicates
  • Ensures test reliability and data comparability

Applications

• Drinking Water and Wastewater Treatment
  Utilities use these methods to monitor ammonia in raw, processed, and discharged waters for regulatory compliance and process control.

• Industrial Process Water Monitoring
  Power plants and manufacturing facilities assess ammonia nitrogen in steam condensates or effluents to prevent equipment corrosion and environmental discharge violations.

• Environmental Water Quality Assessment
  Government agencies and laboratories apply these methods to monitor surface water, ground water, and effluent to protect aquatic life and meet environmental standards.

• Research and Compliance Reporting
  Researchers and laboratory analysts rely on these test methods for consistent ammonia nitrogen measurement in studies and regulatory submissions.

Related Standards

• ASTM D1129 – Terminology Relating to Water
• ASTM D1066 – Practice for Sampling Steam
• ASTM D1193 – Specification for Reagent Water
• ASTM D2777 – Practice for Determination of Precision and Bias
• ASTM D3370 – Practices for Sampling Water from Flowing Process Streams
• Standard Methods for the Examination of Water and Wastewater (APHA, AWWA, WEF)

By referencing ASTM D1426-15(2021)e1 and related standards, laboratories and facilities ensure reliable, internationally recognized practices for monitoring ammonia nitrogen in water-supporting environmental stewardship, operational efficiency, and regulatory compliance.

Keywords: ammonia nitrogen analysis, water quality standards, ASTM D1426, Nesslerization, ion selective electrode, ammonia test method, environmental monitoring, wastewater, drinking water, industrial effluent.

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 [e-mail]. 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.
´1
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 was in place at the time of
of 14 Nessler tubes containing the following volumes of
collaborative testing. Under the allowances made in 1.4 of
standard ammonia nitrogen solution (11.1) diluted to 50 mL
D2777 – 13, these precision and bias data do meet existing
withwater:0.0,0.2,0.4,0.6,0.8,1.0,1.2,1.4,1.7,2.0,2.5,3.0,
requirements for interlaboratory studies of Committee D19 test
3.5, and 4.0 mL. Mix, add 1 mLof Nessler reagent (11.4), and
methods.
remix.
16. Quality Control
13. Procedure
16.1 In order to be certain that analytical values obtained
13.1 If the sample contains turbidity, add 1 mL of ZnSO
using these test methods are valid and accurate within the
solution (11.7) to a 100-mL aliquot and mix. Add NaOH
solution (11.5) with gentle mixing until the pH is about 10.5.
Supporting data have been filed at ASTM International Headquarters and may
Allow to settle and filter (11.3) using a water-washed,
beobtainedbyrequestingResearchReportRR:D19-1015.ContactASTMCustomer
moderately-retentive filter paper, discarding the first 25 mL of Service at [e-mail].
´1
D1426 − 15 (2021)
TABLE 1 Determination of Precision and Bias for Test Method
sample preservation and pretreatment. The result obtained for
A—Direct Nesslerization Method (Photometric at 425 nm)
the LCS shall fall within 615 % of the known concentration.
Precision,
Amount Mean
16.4.2 If the result is not within these limits, analysis of
Matrix Bias,
mg/L
Added, Recovery,
Water %
samples is halted until the problem is corrected, and either all
mg/L %
S S
t o
thesamplesinthebatchmustbereanalyzed,ortheresultsmust
0.120 Reagent 89 0.011 0.003 −10.8
be qualified with an indication that they do not fall within the
0.200 Reagent 98 0.013 0.002 −2.5
0.350 Reagent 98 0.021 0.002 −1.7
performance criteria of the test method.
1.000 Reagent 101 0.042 0.014 + 1.4
16.5 Method Blank:
16.5.1 Analyze a reagent water test blank with each labo-
confidencelimitsofthetest,thefollowingQCproceduresmust ratory defined batch. The concentration of ammonia nitrogen
be followed when analyzing ammonia nitrogen.
found in the blank should be less than 0.5 times the lowest
calibration standard. If the concentration of ammonia nitrogen
16.2 Calibration and Calibration Verification:
is found above this level, analysis of samples is halted until the
16.2.1 Analyze at least three working standards containing
contamination is eliminated, and a blank shows no contamina-
concentrations of ammonia nitrogen that bracket the expected
tion at or above this level, or the results must be qualified with
sample concentration prior to analysis of samples to calibrate
an indication that they do not fall within the performance
the instrument (see 12.1).
criteria of the test method.
16.2.2 Verify instrument calibration after standardization by
analyzing a standard at the concentration of one of the
16.6 Matrix Spike (MS):
calibration standards. The concentration of a mid-range stan-
16.6.1 To check for interferences in the specific matrix
dard should fall within 615 % of the known concentration.
being tested, perform an MS on at least one sample from each
Analyze a calibration blank to verify system cleanliness.
laboratory defined batch by spiking an aliquot of the sample
16.2.3 If calibration cannot be verified, recalibrate the
with a known concentration of ammonia nitrogen and taking it
instrument.
through the analytical method.
16.2.4 It is recommended to analyze a continuing calibra-
16.6.2 Thespikeconcentrationplusthebackgroundconcen-
tion blank (CCB) and continuing calibration verification
tration of ammonia nitrogen must not exceed the high calibra-
(CCV) at a 10 % frequency. The results should fall within the
tion standard. The spike must produce a concentration in the
expected precision of the method or 615 % of the known
spiked sample that is two to five times the analyte concentra-
concentration.
tion in the unspiked sample, or 10 to 50 times the detection
16.3 Initial Demonstration of Laboratory Capability:
limit of the test method, whichever is greater.
16.3.1 Ifalaboratoryhasnotperformedthetestbefore,orif
16.6.3 Calculate the percent recovery of the spike (P) using
there has been a major change in the measurement system, for
the following calculation:
example,newanalyst,newinstrument,andsoforth,aprecision
100 A V 1V 2 BV
@ ~ ! #
s s
and bias study must be performed to demonstrate laboratory
P 5 (3)
CV
capability.
16.3.2 Analyze seven replicates of a standard solution
where:
prepared from an Independent Reference Material covering a
A = analyte known concentration (mg/L) in spiked sample,
midrange concentration of ammonia nitrogen. The matrix and
B = analyte known concentration (mg/L) in unspiked
chemistry of the solution should be equivalent to the solution
sample,
used in the collaborative study. Each replicate must be taken
C = known concentration (mg/L) of analyte in spiking
through the complete analytical test method including any
solution,
sample preservation and pretreatment steps.
V = volume (mL) of sample used, and
s
16.3.3 Calculate the mean and standard deviation of the
V = volume (mL) of spiking solution added.
seven values and compare to the acceptable ranges of bias in
16.6.4 Thepercentrecoveryofthespikeshallfallwithinthe
15.3. This study should be repeated until the recoveries are
limits, based on the analyte concentration, listed in Guide
withinthelimitsgivenin15.3.Ifaconcentrationotherthanthe
D5810, Table 1. If the percent recovery is not within these
recommended concentration is used, refer to Practice D5847
limits, a matrix interference may be present in the sample
for information on applying the F test and t test in evaluating
selected for
...