ASTM D5173-97(2001)
(Test Method)Standard Test Method for On-Line Monitoring of Carbon Compounds in Water by Chemical Oxidation, by UV Light Oxidation, by Both or by High Temperature Combustion Followed by Gas Phase NDIR or by Electrolytic Conductivity
Standard Test Method for On-Line Monitoring of Carbon Compounds in Water by Chemical Oxidation, by UV Light Oxidation, by Both or by High Temperature Combustion Followed by Gas Phase NDIR or by Electrolytic Conductivity
SCOPE
1.1 This test method covers the selection, establishment, and application of monitoring systems for carbon and carbon compounds by continual sampling or continuous flow-through, automatic analysis, and recording or otherwise signaling of output data. The system chosen will depend on the purpose for which it is intended (for example, regulatory compliance, process monitoring, or to alert the user to adverse trends) and on the type of water to be monitored (low purity or high purity, with or without suspended particulates, purgeable organics, or inorganic carbon). If it is to be used for regulatory compliance, the test method published or referenced in the regulations should be used in conjunction with this test method and other ASTM test methods. The test method covers carbon concentrations of 10 µg/L to 5000 mg/L.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 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. For specific hazard statements, see Section 9.
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Designation:D5173–97(Reapproved2001)
Standard Test Method for
On-Line Monitoring of Carbon Compounds in Water by
Chemical Oxidation, by UV Light Oxidation, by Both, or by
High Temperature Combustion Followed by Gas Phase
NDIR or by Electrolytic Conductivity
This standard is issued under the fixed designation D 5173; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3370 Practices for Sampling Water from Closed Con-
duits
1.1 This test method covers the selection, establishment,
D 3694 Practices for Preparation of Sample Containers and
and application of monitoring systems for carbon and carbon
for Preservation of Organic Constituents
compounds by continual sampling or continuous flow-through,
D 3864 Guide for Continual On-Line Monitoring Systems
automatic analysis, and recording or otherwise signaling of
for Water Analysis
output data. The system chosen will depend on the purpose for
D 4453 Practice for Handling of Ultra-PureWater Samples
which it is intended (for example, regulatory compliance,
D 4779 Test Method for Total, Organic, and Inorganic
process monitoring, or to alert the user to adverse trends) and
Carbon in High Purity Water by Ultraviolet (UV) or
on the type of water to be monitored (low purity or high purity,
Persulfate Oxidation, or Both, and Infrared Detection
with or without suspended particulates, purgeable organics, or
D 4839 Test Method for Total Carbon and Organic Carbon
inorganic carbon). If it is to be used for regulatory compliance,
in Water by Ultraviolet, or Persulfate Oxidation, or Both,
the test method published or referenced in the regulations
and Infrared Detection
should be used in conjunction with this test method and other
ASTM test methods. The test method covers carbon concen-
3. Terminology
trations of 10 µg/L to 5000 mg/L.
3.1 Definitions—For definitions of terms used in this test
1.2 The values stated in SI units are to be regarded as the
method, refer to Terminology D 1129 and Guide D 3864.
standard.
1.3 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
4.1 A representative sample of a water stream, or the water
responsibility of the user of this standard to establish appro-
stream itself flows into a reaction chamber where all or some
priate safety and health practices and determine the applica-
of the dissolved organic carbon is oxidized to carbon dioxide
bility of regulatory limitations prior to use. For specific hazard
by either of two means: (1) a chemical oxidant, an energy
statements, see Section 9.
source such as ultraviolet (UV) radiation, or both, or (2) high
temperature combustion. This carbon dioxide is subsequently
2. Referenced Documents
measured in the gas phase by a non-dispersive infrared
2.1 ASTM Standards:
2 detector, or is measured in solution by means of electrolytic
D 1129 Terminology Relating to Water
2 conductivity. Interference may occur from the latter method if
D 1193 Specification for Reagent Water
the water sample has a high conductivity.
D 2777 Practice for Determination of Precision and Bias of
4.2 If there are suspended solids in the water stream, it is
Applicable Test Methods of Committee D-19 on Water
advisable to filter them out to prevent accumulation and
possible blockage in the analyzer. The instrument will then
measure dissolved carbon plus any particulate carbon that
This test method is under the jurisdiction of ASTM Committee D19 on Water
passes the filter. This parameter is usually called dissolved
and is the direct responsibility of Subcommittee D19.03 on Sampling of Water and
carbon.
Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water.
Current edition approved Feb. 10, 1997. Published April 1997. Originally
published as D 5173 – 91. Last previous edition D 5173 – 91 (1995).
2 3
Annual Book of ASTM Standards, Vol 11.01. Annual Book of ASTM Standards, Vol 11.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5173–97 (2001)
4.3 If there is inorganic carbon present in the water (in the
form of carbonate, bicarbonate, or carbon dioxide), it will also
be detected as carbon dioxide. If inorganic carbon is not
removed before analysis, the monitor will report total carbon.
4.4 Inorganic carbon is removed from the water stream by
acidifying and sparging the sample. This process may also
remove purgeable organic compounds.
4.5 Suspended elemental carbon will not be oxidized by
low-temperature methods.
5. Significance and Use
5.1 Accuratemeasurementoforganiccarboninwateratlow
and very low levels is of particular interest to the electronic,
pharmaceutical, and steam power generation industries.
5.2 Elevated levels of organics in raw water tend to degrade
ionexchangeresincapacity.Elevatedlevelsoforganicsinhigh
purity water tend to support biological growth and, in some
cases,aredirectlydetrimentaltotheprocessesthatrequirehigh
purity water.
NOTE 1—The unit employs available water system pressure to rinse the
5.3 In the case of steam power generation, naturally occur-
line and test chamber, followed by a downstream valve closure that
ring organics can become degraded to CO and low molecular
2 isolates the sample. Subsequent irradiation with intense UV light breaks
weight organic acids that, in turn, are corrosive to the process
down organic compounds in the water, with the liberated carbon forming
equipment. Their effect on conductivity may also cause water carbon dioxide in solution as carbonic acid. By monitoring the change in
sample conductivity, corrected for temperature, the TOC concentration is
chemistry operating parameters to be exceeded, calling for
calculated and displayed.
plant shutdown.
FIG. 1 Low Temperature Unit
5.4 In process water in other industries, organic carbon can
signify in-leakage of substances through damaged piping and
8. Reagents and Materials
components, or an unacceptable level of product loss.
5.5 In wastewater treatment, organic carbon measurement
8.1 Purity of Reagents—Reagent grade chemicals shall be
of influent and in-process water can help adjust optimize
usedinalltests.Unlessotherwiseindicated,allreagentsshould
treatment schemes. Measurement of organic carbon at dis-
conform to the specifications of the Committee on Analytical
charge may contribute to regulatory compliance.
Reagents of the American Chemical Society. Other grades
may be used, provided it is first ascertained that the reagent is
6. Interferences
of sufficient purity to permit its use without decreasing the
6.1 If inorganic carbon (dissolved CO and ions in equilib-
accuracy of the determinations.
rium with it) is present, it will give a false positive to an
8.2 Purity of Water:
organic carbon measurement. Ion exchange resins used for
8.2.1 Unless otherwise stated, references to reagent water
high purity water production typically strip CO from the
2 shall be understood to mean that conforming to Specification
water, so this interferent is absent from such water unless the
D 1193, Type II. The carbon content of this water should be
water stream comes in contact with the atmosphere prior to
measured regularly by a suitably sensitive test method, such as
analysis.
Test Method D 4779. It will typically be less than 0.2 mg/L
6.2 If electrolytic conductivity is used for the measurement
carbon.
of CO , other conductive species in solution will cause a
2 8.2.2 Water as free as possible of organics is desirable when
positive interference unless their background conductivity is
establishing the test method blank at carbon levels of less than
measured and deducted.
1 mg/L. Absolutely carbon-free water is not obtainable in
6.3 Particulates suspended in the water stream may cause
ordinary circumstances. However, a working approximation to
blockage in the monitor over a period of time, and may also be
this goal is the solution contained in the reaction vessel of
hard to oxidize. If problems are anticipated, the water stream
carbon analyzers that UV-irradiate and sparge an acidified
should be appropriately filtered upstream of the monitor. The
persulfate solution.Alternatively, water that has been acidified,
parameter measured in the filtered water will be dissolved
mixed with persulfate to a final concentration of 2 % w/v,
organic carbon (DOC).
heated or exposed to ultraviolet radiation, or both, for at least
6.4 Non-dispersive infrared detectors tuned to CO absor-
2 an hour, then thoroughly sparged, may be used.
bance are also sensitive to water vapor, which may therefore
give a positive interference unless removed.
Reagent Chemicals, American Chemical Society Specifications, American
7. Apparatus
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
7.1 Figs. 1-4 show in block diagram form several designs of
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
on-line total organic carbon (TOC) analyzers that have been
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
successfully introduced. MD.
D5173–97 (2001)
NOTE 1—This TOC analysis unit uses ultraviolet-promoted persulfate
NOTE 1—This unit is designed to continually measure TOC in a water
oxidation combined with infrared detection to continuously determine the
sample. The sample flows into a sample overflow chamber and out to
concentration of organics in water. Sample flows continuously into the
drain. Every 5.5 min, acid and sample are aspirated into the carbonate
analyzer through a sample bypass, either by means of process pressure, or
removal system. The inorganic carbon in the combined acid/sample is
an optional sample pump. A side stream for analysis is continuously
sparged with nitrogen gas. A fixed volume of sparged inorganic“ carbon-
pumped at a constant rate and acidified with a sodium persulfate/
free” sample is then injected into the reaction chamber heated at 900°C.
phosphoric acid solution, that reacts with any inorganic carbon to form
The organics in the sample are oxidized to carbon dioxide.The carrier gas
CO . The acidified sample is then sparged with carrier gas (N or O)to
flows continuously through the reaction chamber, carrying the CO
2 2 2
remove the CO . Passing through a liquid/gas separator, the CO is
through a gas-liquid separator into the infrared analyzer. The concentra-
2 2
vented, and the liquid flows to the reaction chamber, where it is exposed
tion of CO measured is directly correlated to the carbon concentration in
to ultraviolet light. The UV radiation catalyzes the persulfate oxidation of
the sample.
the remaining organic carbon to CO .The CO -laden carrier gas is passed
FIG. 2 High Temperature Unit
2 2
through a permeation dryer to remove moisture, and then through the
NDIR detector, that measures the CO . The electronics linearize and scale
the IR detector signal to equate to milligrams/litre organics, displayed on
the digital read-out.
FIG. 4 Low Temperature UV-Persulfate Unit—Continuous Flow
8.3 Amber glass bottles should be used to store reagent
water, organic-free water, and standard solutions. The bottles
should be dedicated to their respective types of solution.
Practices D 3370, D 3694, and D 4453 address handling of
water samples. While the most rigorous method of cleaning
glassware is described below, Practice D 4453 has alternative
procedures not involving Cr(VI).
8.3.1 Clean bottles with chromic acid, rinse several times
with water, and dry overnight at 400°C in a muffle furnace.
8.3.2 Rinse the TFE-fluorocarbon-lined closures several
times with water, then allow to soak in water overnight. Rinse
NOTE 1—Operation—The water sample is pumped continuously to the
conductivity block where the inlet conductivity is measured to establish these closures again with water before use.
the baseline.The sample then flows to the UVreaction chamber where the
8.3.3 Put the closures loosely on the bottles while the latter
organics are oxidized to form organic acids, as described in the following
are still warm. When the bottles have cooled to room tempera-
formula:
ture, tighten the closure.
organics + O + UV light→ rCOOH
8.3.4 Follow the cleaning procedure in 8.3.1 through 8.3.3
As the organics oxidize to organic acids, the conductivity of the sample
before each re-use of the bottles.
increases. Next, the sample flows through the outlet conductivity detector,
8.4 Gas Supply—Use a gas free of CO and organic matter,
and then to drain. The electronics continuously compare the temperature-
corrected conductivity readings from the inlet and outlet detectors, and ofapurityasspecifiedbytheequipmentmanufacturer.Oxygen
derive the organic content of the sample in micrograms/litre that is shown
is recommended.
on a digital display.
8.5 Organic Carbon Solution, Standard:
FIG. 3 Low Temperature Unit—Continuous Flow for High-Purity
8.5.1 Prepare high-concentration calibration standards
Water
(2000 mg/L carbon) using a water-soluble, stable compound.
D5173–97 (2001)
This stock solution can then be further diluted to a concentra- Note that high-purity water monitoring may demand a mini-
tion suitable for the method used. (See 8.5 of Test Method mum of organic polymers in the monitor, while certain process
D 4779.) and waste streams may be highly corrosive and may therefore
8.5.2 The compound used for calibration should be as require inert polymers to be used.
similar as possible to the compound(s) expected to be present 10.7 Select the sampling point(s) so as to provide a repre-
in the water to be analyzed. sentative and measurable sample as close as possible to the
sample system and analyzer, and as outlined in Practices
9. Hazards
D 3370.
9.1 Give full consideration to safe disposal of the analyzer’s
10.8 Select the sample transfer system, including pumps
spent samples and reagents (especially chromic acid), and
and transfer lines, so that the integrity of the sample is
cleaning solutions.
maintained from sampling point to analyzer, especially with
9.2 Provide pressure relief valves, if applicable, to protect
respect to suspension of solids and biological growth.
both the analyzer and monitoring system.
10.9 Provide necessary sample conditioning equipment (for
9.3 Take precautions when using cylinders containing gases
example,filters,diluters,homogenizers
...
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