1、Designation: D7573 09 (Reapproved 2017)Standard Test Method forTotal Carbon and Organic Carbon in Water by HighTemperature Catalytic Combustion and Infrared Detection1This standard is issued under the fixed designation D7573; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of totalcarbon (TC),
3、inorganic carbon (IC), total organic carbon(TOC), dissolved organic carbon (DOC), and non-purgableorganic carbon (NPOC) in water, wastewater, and seawater inthe range from 0.5 mg/L to 4000 mg/L of carbon. Higher levelsmay be determined by sample dilution. The sample is injectedonto a quartz bed heat
4、ed at 680C. The sample converts into agaseous phase and forced through a layer of catalyst ensuringconversion of all carbon containing compounds to CO2.Anon-dispersive infrared (NDIR) detector measures the resultingCO2.1.2 For TOC and DOC analysis a portion of the sample isinjected to determine TC o
5、r dissolved carbon (DC). A portionof the sample is then acidified and purged to remove the IC.The purged inorganic carbon is measured as TIC, or DIC. TOCor DOC is calculated by subtracting the inorganic fraction fromthe total carbon:TOC 5 TC 2 IC1.3 For NPOC analysis a portion of sample is acidified
6、 andpurged to remove IC. The purged sample is then injected todetermine NPOC.1.4 This test method was used successfully with reagentwater spiked with potassium hydrogen phthalate, sucrose,nicotinic acid, benzoquinone, sodium dodecyl benzenesulfonate, urea, acetic acid, and humic acid. It is the user
7、sresponsibility to ensure the validity of this test method forwaters of untested matrices.1.5 This test method is applicable only to carbonaceousmatter in the sample that can be introduced into the reactionzone. The syringe needle or injector opening size generallylimits the maximum size of particle
8、s that can be so introduced.1.6 In addition to laboratory analyses, this test method maybe applied to stream monitoring.1.7 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.8 This standard does not purport to address all of the
9、safety 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. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating t
10、o WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD4129
11、 Test Method for Total and Organic Carbon in Waterby High Temperature Oxidation and by CoulometricDetectionD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer to
12、Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 inorganic carbon (IC), ncarbon in the form ofcarbon dioxide, carbonate ion, or bicarbonate ion.3.2.2 total organic carbon (TOC), ncarbon in the form oforganic compounds.3.2.3 non-purgable organic carbon (NPOC), ncarbonmeasure
13、d in a sample after acidification and sparging toremove inorganic carbon.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substances in Water.Current edition approved Feb. 1, 2017. Publ
14、ished February 2017. Originallyapproved in 2009. Last previous edition approved in 2009 as D7573 09. DOI:10.1520/D7573-09R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was develop
16、ed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.4 total carbon (T
17、C), nthe sum of IC and TOC.3.2.5 dissolved organic carbon (DOC), ncarbon deter-mined on filtered samples.3.2.6 purgable organic carbon (POC), ncarbon thatpurges from acidified samples, also known as volatile organiccompounds (VOC).3.2.7 refractory material, nthat which cannot be oxidizedcompletely u
18、nder the test method conditions.4. Summary of Test Method4.1 FundamentalsCarbon can occur in water as an inor-ganic and organic compound. This test method can be used tomake independent measurements of IC, NPOC, and TC, andcan also determine OC by the difference of TC and IC. DOC isdetermined on sam
19、ples that have been filtered through a0.45-m filter.4.2 TOC and DOC procedures require that IC has beenremoved from the sample before it is analyzed for organiccarbon content. The sample free of IC is injected into the TOCinstrument where all carbon is converted to CO2and measuredby the detector. Fa
20、ilure of the method to remove all IC prior toanalysis for organic carbon will result in significant error. Adiagram of suitable apparatus is given in Fig. 1.5. Significance and Use5.1 This test method is used for determination of the carboncontent of water from a variety of natural, domestic, andind
21、ustrial sources. In its most common form, this test methodis used to measure organic carbon as a means of monitoringorganic pollutants in industrial wastewater. These measure-ments are also used in monitoring waste treatment processes.5.2 The relationship of TOC to other water quality param-eters su
22、ch as chemical oxygen demand (COD) and total oxygendemand (TOD) is described in the literature.46. Interferences and Limitations6.1 The oxidation of dissolved carbon to CO2is broughtabout at high temperatures (680C) in the presence of oxygen.A catalyst promotes the oxidation process and the resultin
23、gcarbon dioxide is measured by a non-dispersive infrareddetector (NDIR). Suspended and refractory materials are com-pletely oxidized under these conditions.6.2 Acid preservation can precipitate some compounds,such as humic acids, removing them from solution and causingerroneously low results.6.3 Hom
24、ogenizing or sparging of a sample, or both, maycause loss of purgable organic compounds, thus yielding avalue lower than the true TOC level. (For this reason, suchmeasurements are sometimes known as NPOC). The extentand significance of such losses must be evaluated on anindividual basis. Comparison
25、of the difference, if any, betweenNPOC and TOC by subtraction represents POC lost duringsparging.6.4 If POC is important then TOC must be measured bysubtraction:TOC 5 TC 2 TIC6.5 Note that error will be introduced when the method ofdifference is used to derive a relatively small level from twolarge
26、levels. For example, a ground water high in IC and lowin TOC will give a poorer TOC value as (TC IC) than bydirect measurement as NPOC.6.6 Samples containing high levels (1 ppm) of surfactantmay lose TOC by foaming.6.7 Elemental carbon may not be completely combusted at680C; however, it is not gener
27、ally found in water samples.Elemental carbon does not form during the catalytic oxidationof water samples.6.8 Inorganics dissolved in the sample are not volatilizedinto gas and remain on the catalyst or quartz shard surfaces.High amounts of solids eventually react with the quartzsurfaces causing dev
28、itrification, or solidify in the catalyst beddecreasing flow rates. Limit sample volume injected to reducethe amount of soluble salts and to reduce cooling of thereaction chamber. Buildup of salts; reduction of flow rate, orlarge injection volumes could result in peak splitting.6.9 Carbon in reagent
29、 water and reagent blanks can bereduced to a minimum, and consistent value, but cannot becompletely eliminated.Analyzing low-level TOC (less than 1.0mg/L) bears special consideration requiring that the same waterused to set the baseline be used to prepare the calibrationstandards.6.10 Atmospheric ca
30、rbon dioxide absorbs into reagent waterincreasing its inorganic carbon content with time. The small4Handbook for Monitoring Industrial Wastewater, Section 5.3, U.S. Environ-ment Protection Agency, August 1973, pp. 512.FIG. 1 TIC RemovalD7573 09 (2017)2levels of CO2absorbed into reagent water can cau
31、se consid-erable inaccuracies in low-level TIC analysis. For instance, a40-milliliter vial of reagent water containing no detectable TICwas analyzed to contain 160 g/LTIC after 1 hour of exposureto ambient air.6.11 Trace organics in the atmosphere can be absorbed intoreagent water increasing its org
32、anic carbon content with time.The small levels of organics absorbed into reagent water cancause considerable inaccuracies in low-level (5 % of the NPOC. Fig.1 illustrates three different options for TIC removal.7.2.1.2 Combustion ChamberA heated catalyst containedin a quartz tube, may contain quartz
33、 wool, quarts shards, orother items to protect the catalyst from dissolved salts to extendits life.7.2.2 Gas ConditioningThe gas passing from the reactoris dried, and the CO2produced is either trapped and later5The sole source of supply of the apparatus known to the committee at this timeis the OI A
34、nalytical Aurora 1030C and 1020. If you are aware of alternativesuppliers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.FIG. 2 Diagram of ApparatusD7573 09
35、(2017)3released to the detector, or routed directly to the detectorthrough a halogen-removing scrubber.7.2.3 DetectorThe CO2in the gas stream is detected by aCO2-specific NDIR detector.7.2.4 Detector ResponseIntegrated area unless CO2iscollected and desorbed from a CO2specific trap. Area integra-tio
36、n accurately quantifies carbon content in the event of split oroverlapping peaks that result from furnace cooling or variablecombustion rates of different organic molecules contained in asample.7.2.5 Presentation of ResultsThe NDIR detector output isrelated to stored calibration data and then displa
37、yed as milli-grams of carbon per liter.7.3 Low TOC Sample ContainersAnalysis of TOC below10 ppm requires the use of sample bottles and vials certified aslow TOC. This avoids variable contribution of TOC and isespecially important when analyzing TOC below 1 ppm.8. Reagents and Materials8.1 Purity of
38、ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of theAmerican Chemical Society,6wheresuch specifications are available. Other grades may be used,provided it is
39、 first ascertained that the reagent is of sufficientpurity to permit its use without lessening the accuracy of thedetermination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D1193, Type I or Type II. The indicat
40、edspecification does not actually specify inorganic carbon ororganic carbon levels but is recommended that NPOC be 0.05mg/L. Higher levels can affect the results of this test method,especially at progressively lower levels of the carbon content inthe samples to be measured. Where inorganic carbon in
41、 reagentwater is significant, CO2-free water may be prepared fromreagent water by acidifying to pH 2, then sparging withfritted-glass sparger using CO2-free gas (time will depend onvolume and gas flow rate, and should be determined by test).Alternatively, if the carbon contribution of the reagent wa
42、ter isknown accurately, its effect may be allowed for in preparationof standards and other solutions. CO2-free water should beprotected from atmospheric contamination. Glass containersare required for storage of water and standard solutions. It isrecommended that the same reagent water be used in pr
43、epara-tion of all standards and blanks per calibration.8.3 AcidAcid is used for sample preservation and TICremoval. Follow the manufacturers suggestions for acid andacid concentration used for TIC removal. Do not use nitricacid.8.4 Organic Carbon, Stock Calibration Standard Solution(1000 mg/L)Weigh
44、2.128 grams of anhydrous potassiumhydrogen phthalate (KHC8H4O4) previously dried for twohours at 120C and quantitatively transfer to a 1000-millilitervolumetric flask containing about 500 milliliters of reagentwater. Stir to dissolve and add 1 milliliter of concentratedhydrochloric acid (HCl), dilut
45、e to the mark with reagent waterand mix. Transfer to an amber glass reagent bottle and cap forstorage. This stock solution, or dilutions of it, is used tocalibrate and test performance of the carbon analyzer.8.5 Organic Carbon, Stock Calibration Verification Solution(1000 mg/L)Weigh 2.377 grams of s
46、ucrose (C12H22O11) andquantitatively transfer to a 1000-milliliter volumetric flaskcontaining about 500 milliliters of reagent water. Stir todissolve and add 1 milliliter of concentrated hydrochloric acid(HCl), dilute to the mark with reagent water and mix. Transferto an amber glass reagent bottle a
47、nd cap for storage. Thissolution, or dilutions of it, is used to verify calibration accuracyand test performance of the carbon analyzer.8.6 Inorganic Carbon, Stock Calibration Standard Solution(1000 mg/L)Weigh 8.826 grams of anhydrous sodium car-bonate (Na2CO3) previously dried at 120C for two hours
48、 andtransfer to a 1000-milliliter volumetric flask containing about500 milliliters of reagent water. Mix to dissolve, dilute to themark, and mix.8.7 Inorganic Carbon, IC Test Solution (Alkalinity 834 mgCaCO3/L)Dilute 10 milliliters of the inorganic carbon stocksolution (Section 8.6) to 100 millilite
49、rs with reagent water. Usethis solution to verify IC removal.8.8 Calibration SolutionsTC, IC8.8.1 Organic Carbon Calibration SolutionsAt least 4calibration concentrations and a calibration blank (CB) areused to prepare an initial calibration curve. Standards areprepared to cover the concentration of interest from the organiccarbon stock calibration solution. Calibration standards areprepared in reagent water and preserved to pH 2 withconcentrated HCl. Filtration of these standards for determina-tion of dissolved organic carbon is unnecessary. The
