ASTM D6317-98(2004)
(Test Method)Standard Test Method for Low Level Determination of Total Carbon, Inorganic Carbon and Organic Carbon in Water by Ultraviolet, Persulfate Oxidation, and Membrane Conductivity Detection
Standard Test Method for Low Level Determination of Total Carbon, Inorganic Carbon and Organic Carbon in Water by Ultraviolet, Persulfate Oxidation, and Membrane Conductivity Detection
SIGNIFICANCE AND USE
This test method is used for determination of the carbon content of water from a variety of natural, domestic, and industrial sources. In its most common form, this test method is used to measure organic carbon as a means of monitoring organic impurities in high purity process water used in industries such as nuclear power, pharmaceutical, and electronics.
SCOPE
1.1 This test method covers the determination of total carbon (TC), inorganic carbon (IC), and total organic carbon (TOC) in water in the range from 10 to 1000 g/L of carbon. This method is for laboratory or grab sample applications and has been subjected to an interlaboratory study under the guidelines of D 2777. Test Method D 5997 can be used for on-line determinations. The test method utilizes persulfate or ultraviolet oxidation of organic carbon, or both coupled with a CO2 selective membrane to recover the CO2 into deionized water. The change in conductivity of the deionized water is measured and related to carbon concentration in the oxidized sample. Inorganic carbon is determined in a similar manner without the oxidation step. In both cases, the sample is acidified to facilitate CO2 recovery through the membrane. The relationship between the conductivity measurement and carbon concentration is described by a set of chemometric equations for the chemical equilibrium of CO2, HCO3 -, and H+, and the relationship between the ionic concentrations and the conductivity. The chemometric model includes the temperature dependence of the equilibrium constants and the specific conductances resulting in linear response of the method over the stated range of TOC. See Test Method D 4519 for a discussion of the measurement of CO2 by conductivity.
1.2 This test method has the advantage of a very high sensitivity detector that allows very low detection levels on relatively small volumes of sample. Also, use of two measurement channels allows determination of CO2 in the sample independently of organic carbon. Isolation of the conductivity detector from the sample by the CO2 selective membrane results in a very stable calibration, with minimal interferences.
1.3 This test method was used successfully with reagent water spiked with various organic materials. It is the user's responsibility to ensure the validity of this test method for waters of untested matrices.
1.4 In addition to laboratory analyses, this test method may be adapted to on line monitoring. See Test Method D 5997.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D6317–98 (Reapproved 2004)
Standard Test Method for
Low Level Determination of Total Carbon, Inorganic Carbon
and Organic Carbon in Water by Ultraviolet, Persulfate
Oxidation, and Membrane Conductivity Detection
This standard is issued under the fixed designation D6317; 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 1.4 In addition to laboratory analyses, this test method may
be adapted to on line monitoring. See Test Method D5997.
1.1 This test method covers the determination of total
1.5 This standard does not purport to address all of the
carbon (TC), inorganic carbon (IC), and total organic carbon
safety concerns, if any, associated with its use. It is the
(TOC) in water in the range from 10 to 1000 µg/L of carbon.
responsibility of the user of this standard to establish appro-
This method is for laboratory or grab sample applications and
priate safety and health practices and determine the applica-
has been subjected to an interlaboratory study under the
bility of regulatory limitations prior to use.
guidelines of D2777. Test Method D5997 can be used for
on-line determinations. The test method utilizes persulfate or
2. Referenced Documents
ultraviolet oxidation of organic carbon, or both coupled with a
2.1 ASTM Standards:
CO selective membrane to recover the CO into deionized
2 2
D1129 Terminology Relating to Water
water. The change in conductivity of the deionized water is
D1192 Guide for Equipment for SamplingWater and Steam
measured and related to carbon concentration in the oxidized
in Closed Conduits
sample. Inorganic carbon is determined in a similar manner
D1193 Specification for Reagent Water
without the oxidation step. In both cases, the sample is
D2777 Practice for Determination of Precision and Bias of
acidifiedtofacilitateCO recoverythroughthemembrane.The
Applicable Test Methods of Committee D19 on Water
relationshipbetweentheconductivitymeasurementandcarbon
D3370 Practices for Sampling Water from Closed Conduits
concentration is described by a set of chemometric equations
– +
for the chemical equilibrium of CO , HCO , and H , and the
2 3
D4210 Practice for Intralaboratory Quality Control Proce-
relationship between the ionic concentrations and the conduc-
dures and a Discussion on Reporting Low-Level Data
tivity. The chemometric model includes the temperature de-
D5997 Test Method for On-Line Monitoring of Total Car-
pendence of the equilibrium constants and the specific conduc-
bon, Inorganic Carbon in Water by Ultraviolet, Persulfate
tancesresultinginlinearresponseofthemethodoverthestated
Oxidation, and Membrane Conductivity Detection
range of TOC. See Test Method D4519 for a discussion of the
D4519 Test Method for On-Line Determination of Anions
measurement of CO by conductivity.
and Carbon Dioxide in High Purity Water by Cation
1.2 This test method has the advantage of a very high
Exchange and Degassed Cation Conductivity
sensitivity detector that allows very low detection levels on
relatively small volumes of sample.Also, use of two measure-
3. Terminology
ment channels allows determination of CO in the sample
3.1 Definitions— For definitions of terms used in this test
independently of organic carbon. Isolation of the conductivity
method, refer to Terminology D1129.
detector from the sample by the CO selective membrane
3.2 Definitions of Terms Specific to This Standard:
results in a very stable calibration, with minimal interferences.
3.2.1 inorganic carbon (IC)—carbon in the form of carbon
1.3 This test method was used successfully with reagent
dioxide, carbonate ion, or bicarbonate ion.
water spiked with various organic materials. It is the user’s
responsibility to ensure the validity of this test method for
waters of untested matrices.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This test method is under the jurisdiction of ASTM Committee D19 on Water Standards volume information, refer to the standard’s Document Summary page on
and is the direct responsibility of Subcommittee D19.03 on Sampling of Water and the ASTM website.
Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water. Withdrawn.
Current edition approved Sept. 10, 1998. Published November 1998. DOI: Withdrawn. The last approved version of this historical standard is referenced
10.1520/D6317-98R04. on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6317–98 (2004)
3.2.2 refractory material—that which cannot be oxidized Other interferences have been investigated and found to be
completely under the test method conditions. minimal under most conditions. Refer to the reference (2) for
3.2.3 total carbon (TC)—the sum of IC and TOC. more information.
3.2.4 total organic carbon (TOC)—carbon in the form of 6.3 Note that error will be introduced when the method of
organic compounds. difference is used to derive a relatively small level from two
large levels. In this case the vacuum degassing unit on the
4. Summary of Test Method instrument should be used to reduce the concentration of IC
prior to measurement. Alternatively, the sample can be acidi-
4.1 Carbon can occur in water as inorganic and organic
fied and sparged prior to introduction into the instrument.
compounds.This test method can be used to make independent
6.4 Use of the vacuum degassing unit or sparging the
measurementsofICandTCandcanalsodetermineTOCasthe
sample may cause loss of volatile organic compounds, thus
difference of TC and IC. If IC is high relative to TOC it is
yielding a value lower than the true TOC level. At low TOC
desirable to use a vacuum degassing unit to reduce the IC
levels,thedegassingunitmayintroduceameasurableTOCand
concentration as part of the measurement.Alternatively, the IC
IC background. The user should characterize the background
can be removed by acidifying and sparging the sample prior to
and performance of the degassing module for their application.
injection into the instrument. The basic steps of the procedure
Table 1 provides typical IC removal performance and back-
are as follows:
ground levels of the vacuum degassing unit.
(1) Removal of IC, if desired, by vacuum degassing;
6.5 ContaminationofthesamplewithbothCO andorganic
(2) Conversion of remaining inorganic carbon to CO by 2
carbon is a severe problem as lower levels of analyte are
action of acid in both channels and oxidation of total carbon to
attempted.Throughoutthismethodtheanalystmustbevigilant
CO by action of ultraviolet (UV) radiation in the TC channel.
for all potential sources of contamination and must monitor
(Acid-persulfate can be added but is usually not required at
blanks and adjust operations to prevent contamination.
TOC levels below 1 ppm).
(3) Detection of CO that is swept out of the U.V. reactor
7. Apparatus
and delay coil by the liquid stream and passed through
7.1 Apparatus for Carbon Determination—Atypical instru-
membranes that allow the specific passage of CO to high
ment consists of reagent and sample introduction mechanism,
purity water where change in conductivity is measured and;
reaction vessel, detector, control system, and a display. Fig. 1
(4) Conversion of the conductivity detector signal to a
shows a diagram of such an arrangement.
display of carbon concentration in parts per million
7.1.1 Sampling Needle— A double chambered needle ca-
(ppm=mg/L) or parts per billion (ppb=µg/L). The IC channel
pable of piercing the sample bottle septum and pulling sample
reading is subtracted from the TC channel to give a TOC
from the bottom of the bottle is used. The second chamber
reading. A diagram of suitable apparatus is given in Fig. 1.
vents the top of the bottle to prevent vacuum build up as the
References 1-5 provide additional information on the method.
sample is withdrawn. Typically this needle is mounted on an
autosampler to provide unattended analysis of several samples.
5. Significance and Use
7.1.2 I.C. Removal— Vacuum degassing requires the manu-
5.1 This test method is used for determination of the carbon
facturer’s module which includes a vacuum pump and a
content of water from a variety of natural, domestic, and
hollow fiber membrane assembly. Use of this vacuum degasser
industrial sources. In its most common form, this test method
will remove essentially all IC as part of the analysis. The
is used to measure organic carbon as a means of monitoring
membrane module consists of a tube and shell arrangement of
organic impurities in high purity process water used in indus-
microporous polypropylene hollow fibers. Sample flows along
tries such as nuclear power, pharmaceutical, and electronics.
the inside of the fibers, while air is passed on the shell
side-counterflow to the sample flow. The shell side pressure is
6. Interferences and Limitations
reduced by means of a vacuum pump on the air outlet. The
6.1 The oxidation of dissolved carbon to CO is brought
sample is acidified before introduction into the degasser to
about at relatively low temperatures by the chemical action of
facilitate CO transport through the hollow fibers. Sparging
reactive species produced by UV-irradiated persulfate ions and
requires an inert vessel with provision for sparging the acidi-
water. Not all suspended or refractory material may be oxi-
fied sample with 50 to 100 mL/min of carbon free gas. This
dized under these conditions; analysts should take steps to
procedure will remove essentially all IC in 2 to 10 min,
determine what recovery is being obtained. This may be done
depending on design.
by several methods: by rerunning the sample under more
7.1.3 Reactor—Thesampleflowissplitaftertheadditionof
vigorousreactionconditionsorbyspikingsampleswithknown
reagents. Half of the flow passes to the delay coil while the
refractories and determining recovery.
other half passes into the oxidation reactor. The effluent from
6.2 Chloride ion above 250 mg/L tends to interfere with
bothstreamspassesoverindividualmembranesthatallowCO
oxidative reaction mechanisms in this test method. Follow
to pas through the membrane into prepurified water for
manufacturer’s instructions for dealing with this problem.
detection.
5 6
The boldface numbers in parentheses refer to the list of references found at the Instruments manufactured and marketed by Sievers Instruments, Inc., 6185
end of this Test Method. Arapahoe Ave., Suite H1, Boulder, CO 80303 have been found satisfactory.
D6317–98 (2004)
FIG. 1 Schematic Diagram of TOC Analyzer System
TABLE 1 Blank Contribution and IC. Removal Efficiency of
7.1.4 Membrane—The membrane is a CO selective fluo-
Vacuum Degassing Unit.
ropolymer which is hydrophobic and non-porous. Refer to the
A A
Unit µg/L TOC µg/L IC IC level with 25 000
bibliography for additional details.
No. background background µg/L input
7.1.5 Detector—The CO that has passed through the mem-
1 3.2 8.2 55
brane into the purified water is measured by conductivity
2 3.2 22 61
3 2.4 8.0 105
sensors. The temperature of the conductivity cell is also
4 4.2 13 89
automatically monitored so the readings can be corrected for
5 2.8 13 30
6 3.0 8.0 70 changes in temperature.
7 4.8 8.9 67
7.1.6 Data Display— The conductivity detector output is
8 4.7 8.3 63
94.6 11 62 relatedtostoredcalibrationdataandthendisplayedaspartsper
10 4.7 2.9 72
million, (ppm = mg of carbon per litre) or parts per billion,
A
Values are the difference between before and after addition of the degasser to
(ppb = µg of carbon per L). Values are given for TC, IC, and
a high purity (<5 µg/L) water stream.
TOC by difference.
D6317–98 (2004)
8. Reagents and Materials required amount of standard in some CO -free water in a 1-L
volumetric flask, add 1 mL of sulfuric acid, and dilute to
8.1 Purity of Reagents—Reagent grade chemicals shall be
volume. Dilutions of this stock solution are to be used to
used in all tests. Unless otherwise indicated, it is intended that
calibrate and test performance of the carbon analyzer.
all reagents conform to the specifications of the Committee on
AnalyticalReagentsoftheAmericanChemicalSociety, where
9. Sampling and Sample Preservation
such specifications are available. Other grades may be used,
provided it is first ascertained that the reagent is of sufficient
9.1 Collect the sample in accordance with Specification
purity to permit its use without lessening the accuracy of the
D1192 and Practices D3370.
determination.
9.2 Samples must be collected in contamination free bottles
8.2 Purity of Water— Unless otherwise indicated, refer-
sealed with a fluoropolymer lined septa. Specially cleaned (for
ences to water shall be understood to mean reagent water
TOC) 40 ml bottles are commercially available. The sample
conforming to Type I or Type II in Specification D1193. The
bottle should be rinsed several times with the sample, filled,
indicated specification does not actually specify inorganic
and then tightly sealed.
carbon or organic carbon levels. These levels can affect the
9.3 To preserve samples for this analysis, store samples in
results of this test method, especially at progressively lower
glass at 4 °C. To aid preservation, acidify the samples to a pH
levels of the carbon content in the samples to be measured.
of 2. It should be noted that acidification will enhance loss of
Where inorganic carbon in reagent water is significant, CO -
inorganiccarbon.Ifthepurgeableorganicfractionisimportant,
freewatermaybepreparedfromreagentwaterbyacidifyingto
fill the sample bottles to overflowing with a minimum of
pH 2, then sparging with fritted-glass sparger using CO -free
turbulence and cap them using a fluoropolymer-lined cap,
gas (time will depend on volume and gas flow rate, and should
without headspace.
be determined by test). The carbon contribution of the reagent
9.4 For water samples where carbon concentrations are
water should be determined and its effect allowed for in
greater than the desired range of instrument operation, dilute
preparation of standards and other solutions. CO -free water
the samples as necessary.
should be protected from atmospheric contamination. Glass
9.5 For accurate measurements of samples containing < 0.5
containers are required for storage of water and standard
mg/L stringent measures must be taken to minimize contami-
solutions. Continuous U.V.
...
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