ASTM C1466-00(2007)
(Test Method)Standard Test Method for Graphite Furnace Atomic Absorption Spectrometric Determination of Lead and Cadmium Extracted from Ceramic Foodware
Standard Test Method for Graphite Furnace Atomic Absorption Spectrometric Determination of Lead and Cadmium Extracted from Ceramic Foodware
SIGNIFICANCE AND USE
Toxic effects of lead and cadmium are well known and release of these elements from foodware is regulated by many countries. Regulatory decisions are based on results of 24-h leaching with acetic acid because results of this test method are precise and accurate and this test method is easy to use. Concentrations of lead and cadmium extracted by food may be different from results of this method, however, because acidity, contact time, and temperature typical of consumer use are different from those of this test method.
This test method is intended for application only in contamination-free settings and should be performed by well-qualified technical personnel. It is recognized that it is not a practical or appropriate method to use in a nonlaboratory environment for quality assurance and control of the ceramic process. Users are advised to use Test Method C 738 (flame AAS) for purposes of the latter.
SCOPE
1.1 This test method covers procedures for using graphite furnace atomic absorption spectroscopy (GFAAS) to quantitatively determine lead and cadmium extracted by acetic acid at room temperature from the food-contact surface of foodware. The method is applicable to food-contact surfaces composed of silicate-based materials (earthenware, glazed ceramicware, decorated ceramicware, decorated glass, and lead crystal glass) and is capable of determining lead concentrations greater than 0.005 to 0.020 g/mL and cadmium concentrations greater than 0.0005 to 0.002 g/mL, depending on instrument design.
1.2 This test method also describes quality control procedures to check for contamination and matrix interference during GFAAS analyses and a specific sequence of analytical measurements that demonstrates proper instrument operation during the time period in which sample solutions are analyzed.
1.3 Cleaning and other contamination control procedures are described in this test method. Users may modify contamination control procedures provided that the modifications produce acceptable results and are used for both sample and quality control analyses.
1.4 The values stated in SI (metric) units are to be regarded as the standard. The values given in parentheses are for information only.
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.
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Designation:C1466–00 (Reapproved 2007)
Standard Test Method for
Graphite Furnace Atomic Absorption Spectrometric
Determination of Lead and Cadmium Extracted from
Ceramic Foodware
This standard is issued under the fixed designation C1466; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope C738 Test Method for Lead and Cadmium Extracted from
Glazed Ceramic Surfaces
1.1 This test method covers procedures for using graphite
furnace atomic absorption spectroscopy (GFAAS) to quantita-
3. Terminology
tively determine lead and cadmium extracted by acetic acid at
3.1 Definitions of Terms Specific to This Standard:
room temperature from the food-contact surface of foodware.
3.1.1 calibration solutions—4% acetic acid solutions con-
Themethodisapplicabletofood-contactsurfacescomposedof
taining known amounts of lead or cadmium which are used to
silicate-based materials (earthenware, glazed ceramicware,
calibrate the instrument.
decoratedceramicware,decoratedglass,andleadcrystalglass)
3.1.2 characteristic mass (m —mass (picograms, pg) of
and is capable of determining lead concentrations greater than
leadorcadmiumthatproducesinstrumentresponse(peakarea)
0.005to0.020µg/mLandcadmiumconcentrationsgreaterthan
of 0.0044 integrated absorbance (absorbance-seconds, A-s).
0.0005 to 0.002 µg/mL, depending on instrument design.
Characteristic mass is a measure of instrument sensitivity and
1.2 This test method also describes quality control proce-
is a function of instrument design, operating conditions, and
dures to check for contamination and matrix interference
analyte-matrix-graphite interactions. Characteristic mass is
during GFAAS analyses and a specific sequence of analytical
calculated from the volume of solution in the furnace and the
measurements that demonstrates proper instrument operation
slopeofthecalibrationcurveortheconcentrationthatgivesan
during the time period in which sample solutions are analyzed.
instrumentresponseinthemiddleoftheworkingrange(thatis,
1.3 Cleaning and other contamination control procedures
approximately 0.100 or 0.200 A-s). Characteristic mass is
are described in this test method. Users may modify contami-
compared to manufacturer specifications to verify that the
nation control procedures provided that the modifications
instrument is optimized.
produce acceptable results and are used for both sample and
3.1.3 check solutions—4% acetic acid solutions containing
quality control analyses.
known amounts of lead or cadmium which are analyzed in the
1.4 The values stated in SI (metric) units are to be regarded
same time period and subjected to the same analytical condi-
as the standard. The values given in parentheses are for
tions and calibration curve as sample solutions. Check solu-
information only.
tions are analyzed to verify that carry-over did not occur and
1.5 This standard does not purport to address all of the
the instrument was operating correctly during the time period
safety concerns, if any, associated with its use. It is the
in which sample solutions were analyzed. Portions of calibra-
responsibility of the user of this standard to establish appro-
tion solutions analyzed as unknown test solutions (as opposed
priate safety and health practices and determine the applica-
to analysis for calibrating the instrument) are used for this
bility of regulatory limitations prior to use.
purpose.
2. Referenced Documents 3.1.4 dilution factor (DF)—factor by which concentration
in test solution is multiplied to obtain concentration in original
2.1 ASTM Standards:
leach solution. For test solutions prepared by mixing pipet-
measured portions of leach solution and diluent, DF=(V +
ThistestmethodisunderthejurisdictionofASTMCommitteeC21onCeramic
V )/V where V and V are volumes of leach solution and
2 1 1 2
Whitewares and Related Products and is the direct responsibility of Subcommittee
diluentintestsolution,respectively.Fortestsolutionsprepared
C21.03 on Methods for Whitewares and Environmental Concerns.
by mixing weighed portions of leach solution (gravimetric
Current edition approved May 1, 2007. Published May 2007. Originally
approved in 2000. Last previous edition approved in 2000 as C1466–00. DOI:
dilution). DF = W /W where: W is the weight of leach
T 1 1
10.1520/C1466-00R07.
solution in test solution and W is the total weight of leach
2 T
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
solution and diluent in the test solution.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1466–00 (2007)
3.1.5 fortified leach solution—a portion of leach solution to ment response (relative variability as a result of instrument
which a known amount of lead or cadmium is added. A precision) is better for 0.050 A-s than for lower values. The
fortified leach solution is analyzed to calculate percent recov- sample concentration limit depends on the characteristic mass
ery and monitor matrix interference. Stock, intermediate, and of the instrument and volume of solution deposited in the
calibration solutions are used to fortify leach solutions.
furnace; the numerical value of the limit increases as charac-
3.1.6 gravimetric dilution—practice of quantitatively pre- teristic mass increases and as the volume of solution deposited
paring dilute solutions from more concentrated ones by com- in the furnace decreases.
bining known weights of diluent and solution of known
3.1.12 sample mass limit (SML)—a low mass (µg) of
concentration. Gravimetric dilution using contamination-free,
extractable lead or cadmium that can be reliably measured by
disposable plasticware is recommended whenever possible
this method. The sample limit is the product of the concentra-
because glass volumetric flasks require time-consuming, acid-
tion limit times the volume of leach solutions.
cleaning procedures to eliminate contamination. Gravimetric
3.1.13 subsample—each of the six individual vessels which
dilution may be used when densities and major components of
make up the sample.
thediluentandconcentratedsolutionarethesame(thatis,both
3.1.14 test solution—solution deposited in the graphite
solutions contain 4% acetic acid). Volumetric flasks must be
furnace for analysis. Test solutions are prepared by diluting
used when the densities are different (that is, as when diluent
leach solutions with known amounts of 4% acetic acid. Test
contains 4% acetic acid and stock standards contain 2% nitric
solutions also include portions of undiluted leach, check, and
acid). Gravimetric dilution is accomplished as follows: weigh
independent check solutions deposited in the furnace.
necessary amount ($1.0000 g) of solution with known con-
3.1.15 working range—range of instrument response that
centration to nearest 0.0001 g in a tared, plastic container.Add
may be described as a linear function of the mass of analyte.
4% acetic acid so that weight of final solution provides
Thelinearrangeofgraphitefurnacepeakareameasurementsis
required concentration. Calculate concentration in final solu-
approximately 0.050 to 0.3500-0.400 A-s. The range of linear
tion as:
response depends on the element and operating conditions and
C 5 C 3 W /W (1)
2 1 1 2
must be verified by analyzing calibration solutions each time
theinstrumentisused.Thelinearrangeofinstrumentresponse
where:
was chosen as the working range of this method because
C = concentration in diluted (final) solution, ng/mL;
responses in the linear range are well below those at which
C = concentration in initial solution, ng/mL;
roll-over adversely affects lead and cadmium instrument re-
W = weight of initial solution, g; and
W = weight of final solution, g.
sponses obtained using Zeeman background correction.
3.1.7 independent check solution—4% acetic acid solution
containing a known amount of lead or cadmium which is from 4. Summary of Test Method
a starting material that is different from the starting material
4.1 Lead and cadmium are extracted from the food-contact
used to prepare calibration solutions. Starting materials with
surface of test vessels by filling them with 4% acetic acid to
different lot numbers are acceptable, but starting materials
within 6 to 7 mm ( ⁄4 in.) of overflowing and leaching them for
from different manufacturers are preferable. The independent
24 h at 20 to 24°C (68 to 75°F). Lead and cadmium are
check solution is analyzed to verify that calibration solutions
determined by GFAAS using a chemical modifier and instru-
have been prepared correctly. An independent check solution
mental background correction. Concentrations in leach solu-
must be used to verify calibration until such time that a
tions are calculated using a calibration curve and linear least
reference material certified for lead and cadmium leaching
squares regression.
becomes available.
3.1.8 leach solution—solution obtained by leaching a test
5. Significance and Use
vessel or method blank with 4% acetic acid for 24 h.
5.1 Toxic effects of lead and cadmium are well known and
3.1.9 method blank—a contamination-free laboratory bea-
release of these elements from foodware is regulated by many
ker or dish that is analyzed by the entire method including
countries. Regulatory decisions are based on results of 24-h
preparation, leaching, and solution analysis.
leachingwithaceticacidbecauseresultsofthistestmethodare
3.1.10 sample—six test vessels of identical size, shape,
precise and accurate and this test method is easy to use.
color, and decorative pattern.
Concentrations of lead and cadmium extracted by food may be
3.1.11 sample concentration limit (SCL)—a low concentra-
differentfromresultsofthismethod,however,becauseacidity,
tion (µg/mL) that can be reliably measured in leach solutions.
contact time, and temperature typical of consumer use are
In this test method, the sample concentration limit is the
different from those of this test method.
concentrationofleadorcadmiumthatproduces0.050A-s.The
value 0.050 A-s is chosen to establish the limit of this test 5.2 This test method is intended for application only in
method for two reasons; 0.050A-s is ten times greater than the contamination-free settings and should be performed by well-
maximum response (0.005 A-s) typically expected from peri- qualified technical personnel. It is recognized that it is not a
odic, repeated analysis of a contamination-free, 0 ng/mL practical or appropriate method to use in a nonlaboratory
solution and thus guarantees that concentrations in sample environment for quality assurance and control of the ceramic
solutions are significantly (ten times) greater than those in a process. Users are advised to use Test Method C738 (flame
true blank; and percent relative standard deviation of instru- AAS) for purposes of the latter.
C1466–00 (2007)
6. Interferences does not need precleaning is preferred. When precleaning is
necessary to eliminate contamination, rinse plastic labware
6.1 Nonspecificabsorptionandscatteringoflightasaresult
with 10% (1+9) nitric acid followed by rinsing with copious
of concomitant species in leach solutions may produce errone-
quantities of reagent water. Air dry the ware in a dust-free
ously high results. Instrumental background correction is used
environment.
to compensate for this interference.
7.6 Glassware—Use new volumetric flasks dedicated for
6.2 Concomitantelementsinleachsolutionsaltertheatomi-
use with only this method to prepare intermediate calibration
zation process and thus degrade or enhance instrumental
solutions. Do not use glassware used for other laboratory
response. This problem, generally referred to as matrix inter-
operations because potential for contamination is too great. Do
ference, is controlled by diluting leach solutions and by using
not use glass pipets.Wash new glassware with warm tap water
a chemical modifier and is monitored by calculating percent 4
and laboratory detergent followed by soaking over night in
recovery from a fortified (spiked) portion of leach solution.
10% (1+9) nitric acid and rinsing with copious quantities of
6.3 Contamination from laboratory glassware, supplies, and
reagent water. Air dry in dust-free environment. Dedicated
environmental particulate matter (dust) may cause erroneously
glassware may be reused after rinsing with copious quantities
high results. Contamination is minimized by keeping work
of reagent water and repeating the acid-cleaning procedure.
areas and labware scrupulously clean, using plastic labware
7.7 Gloves, Powder-Free Vinyl—Wear gloves when han-
whenever possible, using acid-cleaning procedures when glass
dling test vessels to prevent contamination.
labware is required, and protecting samples and supplies from
7.8 Polyethylene Bags, Self-Sealing—Cover or wrap lab-
dust.Analystsmustestablishcontaminationcontrolprocedures
warewithnewplasticbagsofsuitablesizetopreventcontami-
before attempting sample analysis because correcting for lead nation from dust during drying and storage.
and cadmium contamination that is sporadic (heterogeneous)
7.9 Clean-Air Canopy—Laminar flow canopy equipped
bythepracticeof“blanksubtraction”isnotscientificallyvalid. withhigh-efficiencyparticulatefiltersisrecommendedbecause
it makes contamination control easier and analyses faster.
6.4 Spectral interferences due to direct line overlap are
Contamination can be controlled, however, without using a
extremelyrarewhenhollowcathodelampsareusedandarenot
clean-aircanopyifcareistakentopreventcontaminationfrom
expected from leach solutions.
dust.
7. Apparatus
8. Reagents
7.1 Atomic Absorption Spectrometer, capable of displaying
8.1 Purity of Reagents—Reagent grade chemicals may be
and recording fast, transient signals, measuring peak area, and
used in all tests provided that they are of sufficiently high
havingsensitivity(m basedonpeakarea)lessthanorequalto
purity to permit their use without lessening the accuracy of the
30-pg lead and 1.3-pg cadmium when wavelengths 283.3 and
determination. The high sensitivity of graphite furnace may
228.8 nm are used for lead and cadmium determinations,
require reagents of higher purity than reagent grade. At a
respectively; equipped with light sources (hollow cathode or
minimum, all reagents must conform to the specifications of
electrodeless discharge lamps) specific fo
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