1、Designation: D7573 09 (Reapproved 2017)D7573 18Standard 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 yea
2、r oforiginal 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 total carb
3、on (TC), inorganic carbon (IC), total organic carbon (TOC), dissolvedorganic carbon (DOC), and non-purgable organic carbon (NPOC) in water, drinking water, groundwater, surface water, wastewater,and seawater in the range from 0.5 mg/L to 4000 mg/L of carbon. Higher levels 50 mg/L. Concentrations of
4、504000 mg/L ofcarbon may be determined by sample dilution. The sample is injected onto a quartz bed heated at 680C. The sample converts intoa gaseous phase and forced through a layer of catalyst ensuring conversion of all carbon containing compounds to COautomatedinjection of less sample volume or b
5、y sample dilution.Alternatively, use less2.Anon-dispersive infrared (NDIR) detector measuresthe resulting CO sample volume and calibrate at higher concentrations 2.1.2 The sample is injected into a tube heated at 680C. The sample converts into a gaseous phase and forced through a layerof catalyst en
6、suring conversion of all carbon containing compounds to CO2. A non-dispersive infrared (NDIR) detector measuresthe resulting CO2.1.3 For TOC and DOC analysis a portion of the sample is injected to determine TC or dissolved carbon (DC). A portion of thesample is then acidified and purged to remove th
7、e IC. The purged inorganic carbon is measured as TIC, or DIC. TOC or DOC iscalculated by subtracting the inorganic fraction from the total carbon:TOC5TC2IC (1)1.4 For NPOC analysis a portion of sample is acidified and purged to remove IC. The purged sample is then injected todetermine NPOC.1.5 This
8、test method was used successfully with reagent water spiked with potassium hydrogen phthalate, sucrose, nicotinicacid, benzoquinone, sodium dodecyl benzene sulfonate, urea, acetic acid, and humic acid. is applicable to the matrices andconcentrations validated in the inter-laboratory study. It is the
9、 users responsibility to ensure the validity of this test method forwaters of untested matrices.matrices and different concentration ranges.1.6 This test method is applicable only to carbonaceous matter in the sample that can be introduced into the reaction zone. Thesyringe needle or injector openin
10、g size generally limits the maximum size of particles that can be so introduced.1.7 In addition to laboratory analyses, this test method may be applied to stream monitoring.1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1
11、.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations pr
12、ior to use.1.10 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Ba
13、rriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to Water1 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 forOrganic Substances in Water.Cur
14、rent edition approved Feb. 1, 2017Aug. 1, 2018. Published February 2017August 2018. Originally approved in 2009. Last previous edition approved in 20092017 asD7573 09. 09 (2017). DOI: 10.1520/D7573-09R17.10.1520/D7573-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contact
15、ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been m
16、ade to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Co
17、pyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D1192 Guide for Equipment for Sampling Water and Steam in Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias of Ap
18、plicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD4129D4448 Test Method for Total and Organic Carbon in Water by High Temperature Oxidation and by CoulometricDetectionGuide for Sampling Ground-Water Monitoring WellsD5847 Practice for Writing Quali
19、ty Control Specifications for Standard Test Methods for Water AnalysisD6538 Guide for Sampling Wastewater With Automatic SamplersD6759 Practice for Sampling Liquids Using Grab and Discrete Depth Samplers3 The last approved version of this historical standard is referenced on www.astm.org.D7573 1823.
20、 Terminology3.1 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 inorganic carbon (IC), ncarbon in the form of carbon dioxide, carbonate ion, or bicarbonate ion.3.2.2 total organic carbon (TOC), ncar
21、bon in the form of organic compounds.3.2.3 non-purgable organic carbon (NPOC), ncarbon measured in a sample after acidification and sparging to removeinorganic carbon.3.2.4 total carbon (TC), nthe sum of IC and TOC.3.2.5 dissolved organic carbon (DOC), ncarbon determined on filtered samples.3.2.6 pu
22、rgable organic carbon (POC), ncarbon that purges from acidified samples, also known as volatile organic compounds(VOC).3.2.7 refractory material, nthat which cannot be oxidized completely under the test method conditions.4. Summary of Test Method4.1 FundamentalsCarbon can occur in water as an inorga
23、nic and organic compound. This test method can be used to makeindependent measurements of IC, NPOC, and TC, and can also determine OC by the difference of TC and IC. DOC is determinedon samples that have been filtered through a 0.45-m filter.4.2 TOC and DOC procedures require that IC has been remove
24、d from the sample before it is analyzed for organic carboncontent. The sample free of IC is injected into the TOC instrument where all carbon is converted to CO2 and measured by thedetector. Failure of the method to remove all IC prior to analysis for organic carbon will result in significant error.
25、 A diagram ofsuitable apparatus is given in Fig. 1.5. Significance and Use5.1 This test method is used for determination of the carbon content of water from a variety of natural, domestic, and industrialsources. In its most common form, this test method is used to measure organic carbon as a means o
26、f monitoring organic pollutantsin industrial wastewater. These measurements are also used in monitoring waste treatment processes.5.2 The relationship of TOC to other water quality parameters such as chemical oxygen demand (COD) and total oxygendemand (TOD) is described in the literature.44 Handbook
27、 for Monitoring Industrial Wastewater, Section 5.3, U.S. Environment Protection Agency, August 1973, pp. 512.FIG. 1 TIC RemovalD7573 1836. Interferences and Limitations6.1 The oxidation of dissolved carbon to CO2 is brought about at high temperatures (680C) in the presence of oxygen. Acatalyst promo
28、tes the oxidation process and the resulting carbon dioxide is measured by a non-dispersive infrared detector (NDIR).Suspended and refractory materials are completely oxidized under these conditions.6.2 Acid preservation can precipitate some compounds, such as humic acids, removing them from solution
29、 and causingerroneously low results.6.3 Homogenizing or sparging of a sample, or both, may cause loss of purgable organic compounds, thus yielding a value lowerthan the true TOC level. (For this reason, such measurements are sometimes known as NPOC). The extent and significance of suchlosses must be
30、 evaluated on an individual basis. Comparison of the difference, if any, between NPOC and TOC by subtractionrepresents POC lost during sparging.6.4 If POC is important then TOC must be measured by subtraction:TOC5TC2TIC (2)6.5 Note that error will be introduced when the method of difference is used
31、to derive a relatively small level from two largelevels. For example, a ground water high in IC and low in TOC will give a poorer TOC value as (TC IC) than by directmeasurement as NPOC.6.6 Samples containing high levels (1 ppm) of surfactant may lose TOC by foaming.6.7 Elemental carbon may not be co
32、mpletely combusted at 680C; combusted; however, it is not generally found in watersamples. Elemental carbon does not form during the catalytic oxidation of water samples.6.8 Inorganics dissolved in the sample are not volatilized into gas and remain on the catalyst or quartz shard surfaces. Highamoun
33、ts of solids eventually react with the quartz surfaces causing devitrification, or solidify in the catalyst bed decreasing flowrates. Limit sample volume injected to reduce the amount of soluble salts and to reduce cooling of the reaction chamber. Buildupof salts; reduction of flow rate, or large in
34、jection volumes could result in peak splitting.6.9 Carbon in reagent water and reagent blanks can be reduced to a minimum, and consistent value, but cannot be completelyeliminated. Analyzing low-level TOC (less than 1.0 mg/L) bears special consideration requiring that the same water used to setthe b
35、aseline be used to prepare the calibration standards.6.10 Atmospheric carbon dioxide absorbs into reagent water increasing its inorganic carbon content with time. The small levelsof CO2 absorbed into reagent water can cause considerable inaccuracies in low-level TIC analysis. For instance, a 40-mill
36、iliter40-millilitre vial of reagent water containing no detectable TIC was analyzed to contain 160 g/LTIC after 1 hour of exposure toambient air.6.11 Trace organics in the atmosphere can be absorbed into reagent water increasing its organic carbon content with time. Thesmall levels of organics absor
37、bed into reagent water can cause 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 contained in a quartz tube, may contain quartz wool, quarts shards, or otheritems to protect the catalyst f
38、rom dissolved salts to extend its life.7.2.2 Gas ConditioningThe gas passing from the reactor is dried, and the CO2 produced is either trapped and later releasedto the detector, or routed directly to the detector through a halogen-removing scrubber.7.2.3 DetectorThe CO2 in the gas stream is detected
39、 by a CO2-specific NDIR detector.D7573 1847.2.4 Detector ResponseIntegrated area unless CO2 is collected and desorbed from a CO2 specific trap. Area integrationaccurately quantifies carbon content in the event of split or overlapping peaks that result from furnace cooling or variablecombustion rates
40、 of different organic molecules contained in a sample.7.2.5 Presentation of ResultsThe NDIR detector output is related to stored calibration data and then displayed as milligramsof carbon per liter.litre.7.3 Low TOC Sample ContainersAnalysis of TOC below 10 ppm requires the use of sample bottles and
41、 vials certified as lowTOC. This avoids variable contribution of TOC and is especially important when analyzing TOC below 1 ppm.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to th
42、e specifications of the Committee on Analytical Reagents of the American Chemical Society,5 where suchspecifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficient purity to permitits use without lessening the accuracy of the determination
43、.8.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toSpecification D1193, Type I or Type II. The indicated specification does not actually specify inorganic carbon or organic carbonlevels but is recommended that NPOC be 0.05 mg/L.
44、 Higher levels can affect the results of this test method, especially atprogressively lower levels of the carbon content in the samples to be measured. Where inorganic carbon in reagent water issignificant, CO2-free water may be prepared from reagent water by acidifying to pH 2, then sparging with f
45、ritted-glass spargerusing CO2-free gas (time will depend on volume and gas flow rate, and should be determined by test). Alternatively, if the carboncontribution of the reagent water is known accurately, its effect may be allowed for in preparation of standards and other solutions.5 Reagent Chemical
46、s, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
47、Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.FIG. 2 Diagram of ApparatusD7573 185CO2-free water should be protected from atmospheric contamination. Glass containers are required for storage of water andstandard solutions. It is recommended that the same reagent water be used
48、in preparation of all standards and blanks per calibration.8.3 AcidAcid is used for sample preservation and TIC removal. Follow the manufacturers suggestions for acid and acidconcentration used for TIC removal. Do not use nitric acid.8.4 Organic Carbon, Stock Calibration Standard Solution (1000 mg/L
49、)Weigh 2.128 grams of anhydrous potassium hydrogenphthalate (KHC8H4O4) previously dried for two hours at 120C and quantitatively transfer to a 1000-milliliter1000-millilitrevolumetric flask containing about 500 millilitersmillilitres of reagent water. Stir to dissolve and add 1 millilitermillilitre ofconcentrated hydrochloric acid (HCl), dilute to the mark with reagent water and mix. Transfer to an amber glass reagent bottle andcap for storage. This stock solution, or dilutions of it, is used to calibrate and test performance of the carbon ana
