1、Designation: D 5176 91 (Reapproved 2003)Standard Test Method forTotal Chemically Bound Nitrogen in Water by Pyrolysis andChemiluminescence Detection1This standard is issued under the fixed designation D 5176; the number immediately following the designation indicates the year oforiginal adoption or,
2、 in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the totalnitrogen content of water
3、 in concentrations from 0.5 to 1000mg/L. Higher nitrogen concentrations may be determined bymaking the proper dilutions.1.2 This test method does not determine molecular nitrogen(N2).1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informat
4、iononly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Refe
5、renced Documents2.1 ASTM Standards:D 1129 Terminology Relating to Water2D 1193 Specification for Reagent Water2D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on Water23. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer t
6、o Terminology D 1129.3.2 Definition of Term Specific to This Standard:3.2.1 total chemically bound nitrogenall inorganic andorganic nitrogen in the sample, except molecular nitrogen (N2).4. Summary of Test Method4.1 The sample of water is introduced into a stream ofoxygen or inert/oxygen mix flowing
7、 through a quartz pyrolysistube. Oxidative pyrolysis converts chemically bound nitrogento nitric oxide (NO). The gas stream is dried and the NO iscontacted with ozone (O3) producing metastable nitrogendioxide (NO2*). As the NO2* decays, light is emitted anddetected by a photomultiplier tube. The res
8、ulting signal is ameasure of the total chemically bound nitrogen in the sample.5. Significance and Use5.1 This test method is useful for the determination of totalchemically bound nitrogen in wastewaters and other waters.6. Apparatus36.1 Pyrolysis FurnaceAn electric tube furnace capable ofachieving
9、a temperature of 1100C. The furnace may be singleor multizoned and may have common or separate and inde-pendent temperature controls.6.2 Pyrolysis TubeThe pyrolysis tube must be fabricatedfrom quartz and should be designed to ensure completepyrolysis of a wide variety of samples.6.3 Chemiluminescenc
10、e DetectorThe detector shall havea photomultiplier tube capable of sensing the light emission ofthe decaying NO2*. The detector shall have digital display,onboard ozone generator and analog output for data system orstrip chart recorder.6.4 Recorder (optional)The recorder shall be able toaccept a 1 V
11、 full scale signal and to provide a chart speed of 1cm/min.6.5 Microlitre SyringeAny standard series of microlitresyringes with stainless steel needles is acceptable. See manu-facturers instructions for appropriate syringe sizes.6.6 Syringe Drive MechanismThe syringe drive shall becapable of driving
12、 the sample from a microlitre syringe at acontrolled, reproducible rate.6.7 Sample BoatSamples with high concentrations ofsuspended matter or dissolved nonvolatile compounds maytend to plug the syringe needle upon injection into the pyrolysistube. In this case a sample boat of quartz or platinum, wi
13、th orwithout quartz wool, should be used, in conjunction with theappropriate pyrolysis tube. The pyrolysis tube shall allow the1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substance
14、s in Water.Current edition approved March 10, 2003. Published July 2003. Originallyapproved in 1991. Last previous edition approved in 1995 as D 5176 91 (1995).2Annual Book of ASTM Standards, Vol 11.01.3The apparatus described in 6.1-6.7 is manufactured by Antek Instruments, Inc.,Houston, TX and Doh
15、rmann Division of Rosemount Analytical Inc., Santa Clara,CA, and was used in the validation study of this test method.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.introduction of the sample into the boat by microlitre syringewitho
16、ut interrupting the gas flow system.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused. Unless otherwise indicated, it is intended that all reagentsshall conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society.4Other grad
17、es may be used, provided it is first determined thatthe reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D
18、 1193, Type I.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 byaccurately weighing 5.647 g of pyridine into a 100 mLvolumetric flask and dilute to 100 mL with water.7.6 Pyridine Solutions, Standard (1000, 500, 100,
19、 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/Lstandard. Similarly, by serial dilution with water, prepare 500,100, 50, 10, 5, 1, and 0.5 mg N/L standards.8. Preparation of Apparatus8.1 Assemble apparatus according to m
20、anufacturers in-structions.9. Calibration and Standardization9.1 Use the water that was used to prepare the standards asa zero blank standard.9.2 A sample size of 5 to 10 L is sufficient to cover theconcentration range of this test method. The volume of thesample shall be accurately determined.9.3 S
21、yringe InjectionFill the syringe to the 5 L mark andretract the plunger so that the liquid meniscus is at the 1 Lmark. Note the position of the plunger. Insert the syringeneedle through the inlet septum up to the syringe barrel andallow the furnace to burn all nitrogen bearing residue off thesyringe
22、 needle. Reset the detector and inject the sample at acontrolled rate of 1 to 2 L/s. A syringe drive mechanism (see6.6) is strongly recommended. When all sample has beeninjected, withdraw the syringe needle. Retract the plunger sothat the sample meniscus is again at the 1 L point and note theplunger
23、 position. The true amount injected is the differencebetween the two plunger positions.NOTE 1If water samples contain high concentrations of suspendedmatter or dissolved nonvolatile compounds, the syringe needle may tendto plug or the precision and bias of the test method may be degraded. Insuch a c
24、ase, the sample boat system should be used (see 6.7).9.4 Boat InjectionFill the microlitre syringe to the markand inject the sample directly into the boat while holding theneedle in contact with the side of the boat or with the quartzwool.9.5 Determine each calibration standard and the zero blankthr
25、ee times and record the net response from the average ofeach set of standard responses.9.6 By injecting the same volumetric amount of sample foreach determination, the only variables will be total nitrogenconcentration and detector response (digital display). Constructa curve plotting milligrams of
26、N per litre versus detectorresponse. Check the complete calibration curve at least onceper week; check one or two standards daily.10. Procedure10.1 Flush the microlitre syringe several times with theunknown sample. Inject the sample at a controlled rate of 1 to2 g/s as described in 9.3 or inject the
27、 sample into the sampleboat (see 6.7) as described in 9.4.10.2 Set instrument parameters as recommended by manu-facturers. Some changes may be needed to accommodatespecific kinds of samples.11. Calculation11.1 Determine the total chemically bound nitrogen contentof the water sample in milligrams N p
28、er litre by reading off thecalibration curve (see 9.6).12. Precision and Bias12.1 Collaborative TestUsing deionized water as thematrix, a stock solution was prepared containing ammoniumsulfate, potassium nitrate, and pyridine in such proportions thateach compound contributed about one-third of the t
29、otal nitro-gen. Dilutions were made to provide samples of accurately-known concentrations of about 0.5, 1, 10, 100, and 1000 mgN/L. This procedure was repeated, using nitrogen-containingwastewater as the matrix (the wastewater was expected to havea nitrogen content of approximately 20 mg/L, but the
30、actualvalue was found to be about 150 mg/L). The ten samples plusunspiked deionized (DI) water and unspiked wastewater (astrip blanks) were sent to 13 laboratories for analysis intriplicate according to this test method. The laboratories wererequired to make up their own standard solutions, and to u
31、setheir own laboratory water to determine their instrument blank,that they subtracted from their raw results before reportingthem.12.2 Analysis of ResultsOnly nine of the 13 laboratoriessubmitted results for this study. The data were processed asspecified in the 1986 edition of Practice D 2777. The
32、whole ofone laboratorys results for the DI water matrix samples failedthe outlier test.Asingle result from another laboratory was alsorejected as an outlier. One laboratory reported only the averageof its three readings, without standard deviation, and anotherlaboratory did only duplicate runs; the
33、results from these twolaboratories were used where possible. The overall averagevalue for nitrogen in the blank wastewater was calculated bythe collaborative test organizer, who then subtracted it from thereported values for the spiked wastewater samples.4Reagent Chemicals, American Chemical Society
34、 Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical
35、 Convention, Inc. (USPC), Rockville,MD.D 5176 91 (2003)212.3 PrecisionSee Table 1.12.3.1 DI Water MatrixSingle-operator precision is poorat the low levels (1 mg N/L and lower) and adequate to goodat other levels. Overall precision is poor for the central valuesand very poor for the extremes.12.3.2 W
36、astewater MatrixBoth measures of precisionwere poor to very poor over the whole range tested. This maybe attributed in part to the presence of some floccular sedimentin the matrix water that may not have been picked upconsistently by the syringes used in the test method.12.4 BiasSee Table 1.12.4.1 T
37、he negative bias values for the wastewater matrixsamples are larger than those for the DI water matrix becauseof the subtraction of the N content of the matrix water from theraw data.13. Keywords13.1 chemiluminescence; nitrogen; pyrolysisASTM International takes no position respecting the validity o
38、f any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to
39、 revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters.
40、Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is c
41、opyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm
42、.org (e-mail); or through the ASTM website(www.astm.org).TABLE 1 Precision and BiasMatrix WaterAmount Added,mg N/LAmount Found,mg N/LNet Amount,Amg N/LPrecisionBias,mg N/LStSoDI 0.40 0.3 . 0.2 0.1 0.1B1.01 0.8 . 0.4 0.3 0.2B11.1 10.1 . 1.5 0.4 1.0B106 109 . 10 1.0 + 31105 1289 . 298 28 + 184BWaste 0.50 150 2 5 4 20.91 151 1 4 2 210.1 161 9 4 2 195.8 257 105 45 9 + 91008 1336 1184 330 43 + 176B. 152 0 18 3 .AAfter subtraction of wastewater matrixs N content.BBias significant at the 5 % level.D 5176 91 (2003)3
