1、Designation: D7573 09Standard 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 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of totalcarbon (TC), inorganic carbon (
3、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/Lto 4000 mg/Lof carbon. Higher levelsmay be determined by sample dilution. The sample is injectedonto a quartz bed heated at 680C. The samp
4、le 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 or dissolved carbon (
5、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 = TC IC.1.3 For NPOC analysis a portion of sample is acidified andpurged to remove
6、 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 benzene sul-fonate, urea, acetic acid, and humic acid. It is the usersresponsibility to
7、 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 particles that can be so i
8、ntroduced.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 thesafety concerns, i
9、f 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 to WaterD1192 Guide
10、 for Equipment for Sampling Water and Steamin Closed Conduits3D1193 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 Test Method for Total and Organic
11、Carbon in Waterby High Temperature Oxidation and by Coulometric De-tectionD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 Definitions: For definitions of terms used in this testmethod, refer to Terminology D1129.3.2 Definitions o
12、f 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), ncarbonmeasured in a sample after acidification a
13、nd sparging toremove inorganic carbon.3.2.4 total carbon (TC), nthe sum of IC and TOC.3.2.5 dissolved organic carbon (DOC), ncarbon deter-mined on filtered samples.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Met
14、hods forAnalysis forOrganic Substances in Water.Current edition approved Oct. 1, 2009. Published November 2009. DOI:10.1520/D7573-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume infor
15、mation, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.6 purgable org
16、anic carbon (POC), ncarbon thatpurges from acidified samples, also known as volatile organiccompounds (VOC).3.2.7 refractory material, nthat which cannot be oxidizedcompletely under the test method conditions.4. Summary of Test Method4.1 FundamentalsCarbon can occur in water as an inor-ganic and org
17、anic 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 samples that have been filtered through a0.45-m filter.4.2 TOC and DOC procedures require that IC has beenremoved from the sam
18、ple 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. Failure of the method to remove all IC prior toanalysis for organic carbon will result in significant error. Adiagram of suit
19、able 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, andindustrial sources. In its most common form, this test methodis used to measure organic carbon as a means of monitoringorganic
20、 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 such as chemical oxygen demand (COD) and total oxygendemand (TOD) is described in the literature.46. Interferences and Limita
21、tions6.1 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 resultingcarbon dioxide is measured by a non-dispersive infrareddetector (NDIR). Suspended and refractory materials are com-pletely
22、 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 Homogenizing or sparging of a sample, or both, maycause loss of purgable organic compounds, thus yielding avalue lower than th
23、e 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 of the difference, if any, betweenNPOC and TOC by subtraction represents POC lost duringsparging.6.4 If POC is important th
24、en TOC must be measured bysubtraction. TOC = TC TIC.6.5 Note that error will be introduced when the method ofdifference is used to derive a relatively small level from twolarge levels. For example, a ground water high in IC and lowin TOC will give a poorer TOC value as (TC IC) than bydirect measurem
25、ent 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 generally found in water samples.Elemental carbon does not form during the catalytic oxidationof water samples.6.8 Inorganics di
26、ssolved 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 devitrification, or solidify in the catalyst beddecreasing flow rates. Limit sample volume injected to reducethe amount of sol
27、uble 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 water and reagent blanks can bereduced to a minimum, and consistent value, but cannot becompletely eliminated.Analyzing lo
28、w-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 carbon dioxide absorbs into reagent waterincreasing its inorganic carbon content with time. The smalllevels of CO2absorbed in
29、to reagent water can cause 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
30、water increasing its organic carbon content with time.The small levels of organics absorbed into reagent water cancause considerable inaccuracies in low-level (5 % of theNPOC. Fig. 1 illustrates three different options for TICremoval.7.2.1.2 Combustion Chambera heated catalyst containedin a quartz t
31、ube, may contain quartz 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 laterreleased to the detector, or routed directly to the detectorthrough
32、 a halogen-removing scrubber.7.2.3 DetectorThe CO2in the gas stream is detected by aCO2-specific NDIR detector.5The sole source of supply of the apparatus known to the committee at this timeis the OI Analytical Aurora 1030C and 1020. If you are aware of alternativesuppliers, please provide this info
33、rmation 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 0937.2.4 Detector ResponseIntegrated area unless CO2iscollected and desorbed from a CO2specific trap.
34、Area integra-tion 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
35、 and then displayed 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 Materia
36、ls8.1 Purity of 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 use
37、d,provided it is 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
38、 II. The indicatedspecification does not actually specify inorganic carbon ororganic carbon levels but is recommended that NPOC be#0.05 mg/L. Higher levels can affect the results of this testmethod, especially at progressively lower levels of the carboncontent in the samples to be measured. Where in
39、organic carbonin reagent water is significant, CO2-free water may be preparedfrom reagent 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
40、of the reagent water 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 wa
41、ter be used in prepara-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
42、(1000 mg/L)Weigh 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
43、acid (HCl), dilute 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
44、 2.377 grams of sucrose (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
45、 reagent bottle and 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 1
46、20C for two hours 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)
47、 to 100 milliliters 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
48、 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. These stan-dards may be used for T
49、C and NPOC calibrations. For NPOCthe standards are sparged, just like samples, to remove the ICfraction. The calibration blank (CB) is a 0.0 mg C/L standardthat contains the carbon contributed to the calibration standardsby the reagent water. The CB is stored and treated the same asthe calibration standards. These standards, if stored in the dark,are stable for about 30 days and may be used to recalibrate theinstrument within the 30-day period. The CB stored with andprepared from the same reagent water as the calibrationstandards must be used as th
