ASTM D7573-09(2017)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7573 − 09 (Reapproved 2017)
Standard Test Method for
Total Carbon and Organic Carbon in Water by High
Temperature Catalytic Combustion and Infrared Detection
This standard is issued under the fixed designation D7573; 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 1.7 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This test method covers the determination of total
standard.
carbon (TC), inorganic carbon (IC), total organic carbon
1.8 This standard does not purport to address all of the
(TOC), dissolved organic carbon (DOC), and non-purgable
safety concerns, if any, associated with its use. It is the
organic carbon (NPOC) in water, wastewater, and seawater in
responsibility of the user of this standard to establish appro-
therangefrom0.5mg/Lto4000mg/Lofcarbon.Higherlevels
priate safety and health practices and determine the applica-
may be determined by sample dilution. The sample is injected
bility of regulatory limitations prior to use.
onto a quartz bed heated at 680ºC. The sample converts into a
gaseous phase and forced through a layer of catalyst ensuring
2. Referenced Documents
conversion of all carbon containing compounds to CO.A
2.1 ASTM Standards:
non-dispersiveinfrared(NDIR)detectormeasurestheresulting
D1129 Terminology Relating to Water
CO .
D1192 Guide for Equipment for Sampling Water and Steam
1.2 For TOC and DOC analysis a portion of the sample is
in Closed Conduits (Withdrawn 2003)
injected to determine TC or dissolved carbon (DC). A portion
D1193 Specification for Reagent Water
of the sample is then acidified and purged to remove the IC.
D2777 Practice for Determination of Precision and Bias of
The purged inorganic carbon is measured asTIC, or DIC.TOC
Applicable Test Methods of Committee D19 on Water
orDOCiscalculatedbysubtractingtheinorganicfractionfrom
D3370 Practices for Sampling Water from Closed Conduits
the total carbon:
D4129 Test Method for Total and Organic Carbon in Water
TOC 5 TC 2 IC
by High Temperature Oxidation and by Coulometric
Detection
1.3 For NPOC analysis a portion of sample is acidified and
D5847 Practice for Writing Quality Control Specifications
purged to remove IC. The purged sample is then injected to
for Standard Test Methods for Water Analysis
determine NPOC.
1.4 This test method was used successfully with reagent 3. Terminology
water spiked with potassium hydrogen phthalate, sucrose,
3.1 Definitions:
nicotinic acid, benzoquinone, sodium dodecyl benzene
3.1.1 For definitions of terms used in this standard, refer to
sulfonate, urea, acetic acid, and humic acid. It is the user’s
Terminology D1129.
responsibility to ensure the validity of this test method for
3.2 Definitions of Terms Specific to This Standard:
waters of untested matrices.
3.2.1 inorganic carbon (IC), n—carbon in the form of
1.5 This test method is applicable only to carbonaceous
carbon dioxide, carbonate ion, or bicarbonate ion.
matter in the sample that can be introduced into the reaction
3.2.2 total organic carbon (TOC), n—carbon in the form of
zone. The syringe needle or injector opening size generally
organic compounds.
limits the maximum size of particles that can be so introduced.
3.2.3 non-purgable organic carbon (NPOC), n—carbon
1.6 In addition to laboratory analyses, this test method may
measured in a sample after acidification and sparging to
be applied to stream monitoring.
remove inorganic carbon.
1 2
This test method is under the jurisdiction of ASTM Committee D19 on Water For referenced ASTM standards, visit the ASTM website, www.astm.org, or
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Organic Substances in Water. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Feb. 1, 2017. Published February 2017. Originally the ASTM website.
approved in 2009. Last previous edition approved in 2009 as D7573 – 09. DOI: The last approved version of this historical standard is referenced on
10.1520/D7573-09R17. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7573 − 09 (2017)
3.2.4 total carbon (TC), n—the sum of IC and TOC. 5.2 The relationship of TOC to other water quality param-
eterssuchaschemicaloxygendemand(COD)andtotaloxygen
3.2.5 dissolved organic carbon (DOC), n—carbon deter-
demand (TOD) is described in the literature.
mined on filtered samples.
3.2.6 purgable organic carbon (POC), n—carbon that
6. Interferences and Limitations
purges from acidified samples, also known as volatile organic
6.1 The oxidation of dissolved carbon to CO is brought
compounds (VOC).
about at high temperatures (680°C) in the presence of oxygen.
3.2.7 refractory material, n—that which cannot be oxidized
A catalyst promotes the oxidation process and the resulting
completely under the test method conditions.
carbon dioxide is measured by a non-dispersive infrared
detector (NDIR). Suspended and refractory materials are com-
4. Summary of Test Method
pletely oxidized under these conditions.
4.1 Fundamentals—Carbon can occur in water as an inor-
6.2 Acid preservation can precipitate some compounds,
ganic and organic compound. This test method can be used to
such as humic acids, removing them from solution and causing
make independent measurements of IC, NPOC, and TC, and
erroneously low results.
can also determine OC by the difference ofTC and IC. DOC is
6.3 Homogenizing or sparging of a sample, or both, may
determined on samples that have been filtered through a
cause loss of purgable organic compounds, thus yielding a
0.45-µm filter.
value lower than the true TOC level. (For this reason, such
4.2 TOC and DOC procedures require that IC has been
measurements are sometimes known as NPOC). The extent
removed from the sample before it is analyzed for organic
and significance of such losses must be evaluated on an
carbon content. The sample free of IC is injected into the TOC
individual basis. Comparison of the difference, if any, between
instrument where all carbon is converted to CO and measured
NPOC and TOC by subtraction represents POC lost during
by the detector. Failure of the method to remove all IC prior to
sparging.
analysis for organic carbon will result in significant error. A
6.4 If POC is important then TOC must be measured by
diagram of suitable apparatus is given in Fig. 1.
subtraction:
5. Significance and Use
TOC 5 TC 2 TIC
5.1 This test method is used for determination of the carbon 6.5 Note that error will be introduced when the method of
content of water from a variety of natural, domestic, and difference is used to derive a relatively small level from two
industrial sources. In its most common form, this test method large levels. For example, a ground water high in IC and low
is used to measure organic carbon as a means of monitoring in TOC will give a poorer TOC value as (TC – IC) than by
organic pollutants in industrial wastewater. These measure- direct measurement as NPOC.
ments are also used in monitoring waste treatment processes.
6.6 Samples containing high levels (>1 ppm) of surfactant
may lose TOC by foaming.
6.7 Elemental carbon may not be completely combusted at
680ºC; however, it is not generally found in water samples.
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.
High amounts of solids eventually react with the quartz
surfaces causing devitrification, or solidify in the catalyst bed
decreasing flow rates. Limit sample volume injected to reduce
the amount of soluble salts and to reduce cooling of the
reaction chamber. Buildup of salts; reduction of flow rate, or
large injection 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.Analyzinglow-levelTOC(lessthan1.0
mg/L)bearsspecialconsiderationrequiringthatthesamewater
used to set the baseline be used to prepare the calibration
standards.
6.10 Atmosphericcarbondioxideabsorbsintoreagentwater
increasing its inorganic carbon content with time. The small
Handbook for Monitoring Industrial Wastewater, Section 5.3, U.S. Environ-
FIG. 1 TIC Removal ment Protection Agency, August 1973, pp. 5–12.
D7573 − 09 (2017)
levels of CO absorbed into reagent water can cause consid- detector, a control system, and a display. Fig. 1 shows a
erable inaccuracies in low-level TIC analysis. For instance, a diagram of such an arrangement.
40-milliliter vial of reagent water containing no detectableTIC 7.2.1 Reaction vessel consists of TIC removal and the
was analyzed to contain 160 µg/LTIC after 1 hour of exposure combustion chamber.
to ambient air.
7.2.1.1 TIC Removal—Sparging requires an inert vessel
with a capacity of at least double the sample size with
6.11 Trace organics in the atmosphere can be absorbed into
provision for sparging with 50 to 200 mL/min of carbon-free
reagent water increasing its organic carbon content with time.
gas. This procedure should remove essentially all IC in 2 to 10
The small levels of organics absorbed into reagent water can
min, depending on design and can be at room temperature or at
cause considerable inaccuracies in low-level (<1 mg/L) TOC
elevatedtemperatures(≤70°C)topromoteCO removal.Verify
measurements.
that heated sparging does not remove >5 % of the NPOC. Fig.
1 illustrates three different options for TIC removal.
7. Apparatus
NOTE 1—See also Fig. 2.
7.2.1.2 Combustion Chamber—A heated catalyst contained
in a quartz tube, may contain quartz wool, quarts shards, or
7.1 Sampling Devices—Manually operated or automatically
otheritemstoprotectthecatalystfromdissolvedsaltstoextend
operated sampling valves, or syringes are typically used with
its life.
this method. Sampling devices with inside diameters as small
7.2.2 Gas Conditioning—The gas passing from the reactor
as 0.15 mm may be used with samples containing little or no
is dried, and the CO produced is either trapped and later
particulate matter. Larger inside dimensions, such as 0.2 mm,
will be required for samples with particulate matter.
7.2 Apparatus for Carbon Determination—This instrument
The sole source of supply of the apparatus known to the committee at this time
consists of reagent and sample introduction mechanism, a
is the OI Analytical Aurora 1030C and 1020. If you are aware of alternative
gas-sparged reaction vessel forTIC removal, the high tempera-
suppliers, please provide this information to ASTM International Headquarters.
ture combustion chamber with catalyst, a gas demister or dryer
Your comments will receive careful consideration at a meeting of the responsible
and halogen trap, an optional CO trap, a CO -specific infrared technical committee, which you may attend.
2 2
FIG. 2 Diagram of Apparatus
D7573 − 09 (2017)
released to the detector, or routed directly to the detector 8.4 Organic Carbon, Stock Calibration Standard Solution
through a halogen-removing scrubber. (1000 mg/L)—Weigh 2.128 grams of anhydrous potassium
7.2.3 Detector—The CO in the gas stream is detected by a
hydrogen phthalate (KHC H O ) previously dried for two
2 8 4 4
CO -specific NDIR detector.
hours at 120ºC and quantitatively transfer to a 1000-milliliter
7.2.4 Detector Response—Integrated area unless CO is
volumetric flask containing about 500 milliliters of reagent
collected and desorbed from a CO specific trap.Area integra-
water. Stir to dissolve and add 1 milliliter of concentrated
tion accurately quantifies carbon content in the event of split or
hydrochloric acid (HCl), dilute to the mark with reagent water
overlapping peaks that result from furnace cooling or variable
and mix. Transfer to an amber glass reagent bottle and cap for
combustion rates of different organic molecules contained in a
storage. This stock solution, or dilutions of it, is used to
sample.
calibrate and test performance of the carbon analyzer.
7.2.5 Presentation of Results—The NDIR detector output is
8.5 OrganicCarbon,StockCalibrationVerificationSolution
related to stored calibration data and then displayed as milli-
(1000 mg/L)—Weigh 2.377 grams of sucrose (C H O ) and
12 22 11
grams of carbon per liter.
quantitatively transfer to a 1000-milliliter volumetric flask
7.3 Low TOC Sample Containers—Analysis of TOC below
containing about 500 milliliters of reagent water. Stir to
10 ppm requires the use of sample bottles and vials certified as
dissolve and add 1 milliliter of concentrated hydrochloric acid
low TOC. This avoids variable contribution of TOC and is
(HCl), dilute to the mark with reagent water and mix. Transfer
especially important when analyzing TOC below 1 ppm.
to an amber glass reagent bottle and cap for storage. This
solution,ordilutionsofit,isusedtoverifycalibrationaccuracy
8. Reagents and Materials
and test performance of the carbon analyzer.
8.1 Purity of Reagents—Reagent grade chemicals shall be
8.6 Inorganic Carbon, Stock Calibration Standard Solution
used in all tests. Unless otherwise indicated, it is intended that
(1000 mg/L)—Weigh 8.826 grams of anhydrous sodium car-
all reagents conform to the specifications of the Committee on
bonate (Na CO ) previously dried at 120ºC for two hours and
AnalyticalReagentsoftheAmericanChemicalSociety, where 2 3
transfer to a 1000-milliliter volumetric flask containing about
such specifications are available. Other grades may be used,
500 milliliters of reagent water. Mix to dissolve, dilute to the
provided it is first ascertained that the reagent is of sufficient
mark, and mix.
purity to permit its use without lessening the accuracy of the
determination.
8.7 Inorganic Carbon, IC Test Solution (Alkalinity 834 mg
8.2 Purity of Water—Unless otherwise indicated, references
CaCO /L)—Dilute 10 milliliters of the inorganic carbon stock
towatershallbeunderstoodtomeanreagentwaterconforming
solution (Section 8.6) to 100 milliliters with reagent water. Use
to Specification D1193, Type I or Type II. The indicated
this solution to verify IC removal.
specification does not actually specify inorganic carbon or
8.8 Calibration Solutions—TC, IC
organiccarbonlevelsbutisrecommendedthatNPOCbe≤0.
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