ASTM D5176-20

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Designation: D5176 − 08 (Reapproved 2015) D5176 − 20
Standard Test Method for
Total Chemically Bound Nitrogen in Water by Pyrolysis and
Chemiluminescence Detection
This standard is issued under the fixed designation D5176; 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 This test method covers the determination of the total nitrogen content of water in concentrations from 0.5 to 1000 mg/L.
Higher nitrogen concentrations may be determined by making the proper dilutions.
1.2 This test method does not determine molecular nitrogen (N ).
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 safety, health, and healthenvironmental 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
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis
3. Terminology
3.1 Definitions:
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 total chemically bound nitrogen, n—all inorganic and organic nitrogen in the sample, except molecular nitrogen (N ).
4. Summary of Test Method
4.1 The sample of water is introduced into a stream of oxygen or inert/oxygen mix flowing through a quartz pyrolysis tube.
Oxidative pyrolysis converts chemically bound nitrogen to nitric oxide (NO). The gas stream is dried and the NO is contacted with
ozone (O ) producing metastable nitrogen dioxide (NO *). As the NO * decays, light is emitted and detected by a photomultiplier
3 2 2
tube. The resulting signal is a measure of the total chemically bound nitrogen in the sample.
5. Significance and Use
5.1 This test method is useful for the determination of total chemically bound nitrogen in wastewaters and other waters.
This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.06 on Methods for Analysis for
Organic Substances in Water.
Current edition approved June 15, 2015July 15, 2020. Published June 2015July 2020. Originally approved in 1991. Last previous edition approved in 20082015 as
D5176 – 08.D5176 – 08 (2015). DOI: 10.1520/D5176-08R15.10.1520/D5176-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
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D5176 − 20
6. Apparatus
6.1 Pyrolysis Furnace—An electric tube furnace capable of achieving a temperature of 1100°C. The furnace may be single or
multizoned and may have common or separate and independent temperature controls.
6.2 Pyrolysis Tube—The pyrolysis tube must be fabricated from quartz and should be designed to ensure complete pyrolysis of
a wide variety of samples.
6.3 Chemiluminescence Detector—The detector shall have a photomultiplier tube capable of sensing the light emission of the
decaying NO *. The detector shall have digital display, onboard ozone generator and analog output for data system or strip chart
recorder.
6.4 Recorder (optional)—The recorder shall be able to accept a 1 V full scale signal and to provide a chart speed of 1 cm/min.
6.5 Microlitre Syringe—Any standard series of microlitre syringes with stainless steel needles is acceptable. See
manufacturer’smanufacturer’s instructions for appropriate syringe sizes.
6.6 Syringe Drive Mechanism—The syringe drive shall be capable of driving the sample from a microlitre syringe at a
controlled, reproducible rate.
6.7 Sample Boat—Samples with high concentrations of suspended matter or dissolved nonvolatile compounds may tend to plug
the syringe needle upon injection into the pyrolysis tube. In this case a sample boat of quartz or platinum, with or without quartz
wool, should be used, in conjunction with the appropriate pyrolysis tube. The pyrolysis tube shall allow the introduction of the
sample into the boat by microlitre syringe without interrupting the gas flow system.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used. 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. Other grades may be
used, provided it is first determined that the reagent is of sufficiently high purity to permit its use without lessening the accuracy
of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water that meets the
purity specifications of Type I or Type II water, presented in Specification D1193.
7.3 Inert Gas, Argon (minimum purity 99.99 %).
7.4 Oxygen (minimum purity 99.6 %).
7.5 Stock Solution, Pyridine (10 000 mg N/L)—Prepare by accurately weighing 5.647 g of pyridine into a 100 mL volumetric
flask and dilute to 100 mL with water.
7.6 Pyridine Solutions, Standard (1000, 500, 100, 50, 10, 5, 1, and 0.5 mg N/L)—Dilute ten volumes of the stock solution (see
6.5) with 90 volumes of water to prepare a 1000 mg N/L standard. Similarly, by serial dilution with water, prepare 500, 100, 50,
10, 5, 1, and 0.5 mg N/L standards.
8. Preparation of Apparatus
8.1 Assemble apparatus according to manufacturer’smanufacturer’s instructions.
9. Calibration and Standardization
9.1 Use the water that was used to prepare the standards as a zero blank standard.
9.2 A sample size of 5 to 10 μL is sufficient to cover the concentration range of this test method. The volume of the sample shall
be accurately determined.
9.3 Syringe Injection—Fill the syringe to the 5 μL mark and retract the plunger so that the liquid meniscus is at the 1 μL mark.
Note the position of the plunger. Insert the syringe needle through the inlet septum up to the syringe barrel and allow the furnace
to burn all nitrogen bearing residue off the syringe needle. Reset the detector and inject the sample at a controlled rate of 1 to 2
μL/s. A syringe drive mechanism (see 6.6) is strongly recommended. When all sample has been injected, withdraw the syringe
needle. Retract the plunger so that the sample meniscus is again at the 1 μL point and note the plunger position. The true amount
injected is the difference between the two plunger positions.
NOTE 1—If water samples contain high concentrations of suspended matter or dissolved nonvolatile compounds, the syringe needle may tend to plug
The apparatus described in 6.1 – 6.7 is manufactured by Antek Instruments, Inc., Houston, TX, and Dohrmann Division of Rosemount Analytical Inc., Santa Clara, CA,
and was used in the validation study of this test method.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. PharmaceuticalPharmacopeial Convention, Inc.
(USPC), Rockville, MD.
D5176 − 20
or the precision and bias of the test method
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