ASTM D6903-07

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6903 − 07
StandardTest Method for
Determination of Organic Biocide Release Rate From
Antifouling Coatings in Substitute Ocean Water
This standard is issued under the fixed designation D6903; 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 tively. Other methods may be used provided that they meet the
appropriate criteria given in Annex A2.
1.1 This test method covers the laboratory determination of
the rate at which organic biocide is released from an antifoul- 1.5 When the release rate of a highly photosensitive organic
ing coating exposed in substitute ocean water. The test is run biocide is being determined, steps must be taken to protect the
entirely in the laboratory under controlled conditions of pH, apparatus and samples from exposure to natural and artificial
temperature, salinity, and hydrodynamics. Analytical proce- visible light sources. Any such requirement for these steps to
dures are provided for the determination of the release rate of be taken for a particular biocide is indicated in Annex A2.
4,5-dichloro-2-n-octylisothiazolin-3-one (DCOIT), zinc and
1.6 The practical limits for quantifying biocide release rates
copper pyrithione (ZPT and CuPT), and N-cyclopropyl-N’-(1, -2 -1
bythismethodarefrom4.5to500 µgcm d forDCOIT,0.36
1-dimethylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine -2 -1 -2 -1
to 500 µgcm d for CuPT, 0.36 to 500 µgcm d for ZPT,
(CDMTD). At predetermined intervals, substitute ocean water -2 -1
and 2.7 to 500 µgcm d for CDMTD. These ranges may be
samples are analyzed for leached biocide using a suitable -2 -1
extended to 3.8 to 500 µgcm d for DCOIT, 0.16 to 500 µg
-2 -1 -2 -1
analytical technique.
cm d for CuPT, 0.2 to 500 µgcm d for ZPT, and 2.2 to
-2 -1
1.2 In cases in which the antifouling coating contains both 500 µgcm d for CDMTD if the procedures described in
an organic biocide and a copper-based biocide, the release rate Appendix X1-Appendix X3 (as appropriate) are followed. The
of copper may optionally be concurrently determined accord- quantitation of release rates lower than these ranges will
ing to the procedure found in Test Method D6442. require the use of analytical methods with lower limits of
quantitation than those specified in Annex A2.
1.3 The procedure contains the preparation steps for the
determination of the release rate of biocide in substitute ocean 1.7 The results of this test method do not reflect environ-
water from antifouling paints including apparatus, reagents, mental biocide release rates for antifouling products, and are
holding tank conditions, and sampling point details. The not suitable for direct use in the process of generating
procedure calls for the accurate determination of organic environmental risk assessments, environmental loading
biocide concentrations in substitute ocean water at the low µg estimates, or for establishing release rate limits for regulatory
-1
L (parts per billion, ppb) level. To detect and correct for purposes. See also Section 4.
reagent impurities and allow a suitable level of analytical
1.8 The values stated in SI units are to be regarded as the
precision to be achieved, the analytical method to be used for
standard. The values given in parentheses are for information
the determination of the concentration of organic biocide in
only.
substitute ocean water must meet the acceptability criteria
1.9 This standard does not purport to address all of the
given in Annex A2. Where Annex A2 specifies a limit of
safety concerns, if any, associated with its use. It is the
quantitation(LOQ),theprocedurefordeterminingtheLOQfor
responsibility of the user of this standard to establish appro-
the organic biocide in substitute ocean water by the analytical
priate safety and health practices and determine the applica-
method presented in Annex A3 is to be followed.
bility of regulatory limitations prior to use.
1.4 Suitable analytical methods that use high-performance
2. Referenced Documents
liquid chromatography (HPLC) for determining the concentra-
tion of DCOIT, ZPT and CuPT, and CDMTD in substitute
2.1 ASTM Standards:
ocean water are given in Appendix X1-Appendix X3, respec-
D1005 Test Method for Measurement of Dry-Film Thick-
ness of Organic Coatings Using Micrometers
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Subcommittee D01.45 on Marine Coatings. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Feb. 1, 2007. Published March 2007. DOI: 10.1520/ Standards volumeinformation,refertothestandard’sDocumentSummarypageon
D6903-07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6903 − 07
D1141 Practice for the Preparation of Substitute Ocean 4.3 By comparison with published copper and organotin
4,5
Water release rate data obtained either by direct measurements
D1193 Specification for Reagent Water from ship hulls or release rate measurements from harbor
D6442 Test Method for Determination of Copper Release exposed panels, all data indicate that the results of this generic
Rate From Antifouling Coatings in Substitute Ocean rotating-cylinder test method significantly overestimate the
Water release rate of biocide when compared to release rates under
3 in-service conditions. For example, published results demon-
2.2 U.S. Federal Standard:
strate that this generic test method produces higher measure-
40 CFR 136, Appendix B, revision 1.11
ments of copper and organotin release rates than from direct in
situmeasurementsforthesamecoatingonin-serviceshiphulls
3. Summary of Test Method
and harbor-exposed panels. The difference between the results
3.1 The candidate paint system is applied to the cylindrical
of this test method and the panel and ship studies was up to a
test specimens. The coated specimens are placed in a tank of
factor of about 30 based on copper release rate data for several
4,6
substitute ocean water in which the levels of organic biocide
commercial antifouling coatings. No direct release rate data
and copper (where the coating also contains a biocidal copper
from ship hulls or harbor-exposed panels have been generated
-1
compound) are kept below 100 µgL by circulating the
to-date for the biocides covered by this method. However, the
substitute ocean water through a suitable filtration system (see
expectation is that the results of this test method, when
5.1.3). At specified intervals, each specimen is placed in 1500
compared with the direct measurements from ship hulls and
mL of substitute ocean water (see Section 8 for details) and
harbor-exposed panels, could follow the same trend. Realistic
rotatedat60rpmfor1h(orless,see8.7forfurtherexplanation
estimates of the biocide release from a ship’s hull under
and instruction). The rate of biocide release from the paint is
in-service conditions can only be obtained from this test
determined by measuring concentrations of the biocide in the
method where the difference between the results obtained by
substitute ocean water in the individual measuring containers.
this test method and the release rate of an antifouling coating
in service is taken into account.
3.2 Annex A2 provides acceptance criteria for analytical
procedures for measuring the concentration of specific organic
4.4 Where the results of this test method are used in the
biocides in substitute ocean water. Suitable methods are
process of generating environmental risk assessments, for
provided in Appendix X1-Appendix X3. Alternative methods
environmental loading estimates, or for regulatory purposes, it
may be used provided that they meet the acceptance criteria
is most strongly recommended that the relationship between
given in Annex A2.
laboratory release rates and actual environment inputs is taken
into account to allow a more accurate approximation of the
4. Significance and Use
biocide release rate from antifouling coatings under real-life
conditions. This can be accomplished through the application
4.1 This test method is designed to provide a laboratory
of appropriate correction factors.
procedure to quantify and characterize changes in the release
rate of organic biocide from antifouling coatings that occur
5. Apparatus
during a period of immersion under specified laboratory
conditions of constant temperature, pH, salinity, and hydrody- 5.1 Sample Generation—SeeAnnexA2forguidanceonany
namics. Quantitative measurement of biocide release rate is particular materials restriction and handling requirements re-
lating to each organic biocide.
necessary to help in selection of materials, providing quality
control, and understanding the performance mechanism. 5.1.1 Release Rate Measuring Container—A nominal 2-L
( ⁄2-gal) container made of an inert material, approximately
4.2 Results from this test method establish a pattern of
13.5 cm (5.3 in.) in diameter and 19 cm (7.5 in.) high, is fitted
biocide release from an antifouling coating over a minimum of
with three rods also made of an inert material, approximately 6
45 days exposure under controlled laboratory conditions.
mm (nominal ⁄4 in.) in diameter to serve as baffles. Rods shall
Biocide release rates of antifouling paints in-service vary over
be evenly spaced on the inside circumference of the container
thelifeofthecoatingsystemdependingontheformulationand
to prevent swirling of the water with the test cylinder during
on the physical and chemical properties of the environment.
rotation. The rods will be secured to the container walls using
Factors such as differences in berthing locations, operating
an inert adhesive. The material of construction of the release
schedules, length of service, condition of paint film surface,
rate measuring container and rods for use with any particular
temperature, pH, and salinity influence the actual release rate
biocide shall be as specified in A2.3. When the release rate of
under environmental conditions. Results obtained using this
a photosensitive material is to be determined, the container
test method do not reflect actual biocide release rates that will
shall be protected from light. The requirement to protect the
occur in service, but provide comparisons of the release rate
characteristics of different antifouling formulations in substi-
tute ocean water under the prescribed laboratory conditions. 4
Valkirs, A. O., Seligman, P. F., Haslbeck, E., and Caso, J. S., Marine Bulletin,
Vol. 46 (2003), pp. 763–779.
Champ, M.A. and Seligman, P. F., Organotin: Environmental Fate and Effects,
Chapter 19 — Measurement and Significance of the Release Rate for Tributyltin,
AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments, (1996) Chapman and Hall, pp 383–403.
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:// Finnie,A.A.,ImprovedEstimatesofEnvironmentalCopperReleaseRateFrom
www.access.gpo.gov. Antifouling Coatings, Biofouling, Vol. 22 (2006), pp 279–291.
D6903 − 07
release rate container from light for any particular organic material of construction of the test cylinder (including the
biocide is indicated in A2.4. bottom end-disk) for use with any particular biocide shall be as
specified in A2.3. It is advisable to weight the cylinder by
NOTE1—Theresultsofthistestmethodwillbeadverselyaffectedifthe
filling with water so that the unit does not have buoyancy.
biocide is strongly adsorbed or absorbed by the release rate measuring
container or the test cylinder, or both. Where the release rates of two or
NOTE 2—When coating release rates are very high, it may be desirable
moredifferentbiocidesaretobeconcurrentlydeterminedfromasingleset 2 -1
to use a 5-cm band (100-cm paint area) to avoid exceeding 200 µgL
ofmeasurements,thereleaseratemeasuringcontainer,associatedrodsand
of organic biocide in the measuring containers (see 8.7.1).
the test cylinders must all be made of a material that is inert to all of the
biocides, otherwise repeat testing (different cylinders and measuring 5.1.6 Test Cylinder Rotating Device—The device shall be
containers) for each biocide will be required.
capable of rotating the test cylinder in the release rate measur-
-1
ing container at 60 6 5 rpm (0.2 6 0.02 m s , velocity of test
5.1.2 Constant Temperature Control—This control is a
cylinder surface). No part of the rotating device shall be
means of maintaining the release rate measuring containers at
immersed in substitute ocean water.
a temperature of 25 6 1°C during the rotation period (see 8.7).
5.1.7 pH Meter, with a suitable electrode.
5.1.3 Holding Tank—This tank is an inert plastic container
5.1.8 Appropriate Hydrometer or Salinometer.
of such dimensions so as to permit immersion of four or more
test cylinders and must be equipped with a system to circulate
5.2 Analysis of Leachate—Suitable analytical procedures
the seawater continuously in the tank through an activated
are provided for the determination of the release rate of
carbon filter and, optionally, an absorbent filter. If an absor-
4,5-dichloro-2-n-octylisothiazolin-3-one (DCOIT), zinc and
bent filter is used, regenerate the ion exchange resin following
copper pyrithione (ZPT and CuPT), and N-cyclopropyl- N’-
the manufacturer’s instructions and wash the resin with sub-
(1,1-dimethylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine
stitute ocean water before use. The rate of water flow and the
(CDMTD). Refer to Appendix X1-Appendix X3 for additional
size of the filter shall be selected to maintain the concentration
apparatus requirements for the analysis of specific organic
-1
ofeachorganicbiocidebelow100 µgL (100ppb)and,when
biocides in which these analytical methods are to be used.
the coating contains a biocidal copper compound, the concen-
-1
6. Reagents and Materials
tration of copper below 100 µgL . Flow rates should be set to
obtaintwotoeightturnoversperhour.Whenthereleaserateof
6.1 Sample Generation:
a photosensitive material is to be determined, the holding tank
6.1.1 Purity of Reagents—Reagent grade chemicals shall be
shall be protected from light. The requirement to protect
used in all tests, unless otherwise indicated. It is intended that
holding tank from light for any particular organic biocide is
all reagents conform to the specifications of the Committee on
indicated in A2.4.
Analytical Reag
...