ASTM C1466-00(2012)
(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 C738 (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 μg/mL and cadmium concentrations greater than 0.0005 to 0.002 μg/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 2012)
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 2. Referenced Documents
1.1 This test method covers procedures for using graphite 2.1 ASTM Standards:
furnace atomic absorption spectroscopy (GFAAS) to quantita- C738Test Method for Lead and Cadmium Extracted from
tively determine lead and cadmium extracted by acetic acid at Glazed Ceramic Surfaces
room temperature from the food-contact surface of foodware.
3. Terminology
Themethodisapplicabletofood-contactsurfacescomposedof
3.1 Definitions of Terms Specific to This Standard:
silicate-based materials (earthenware, glazed ceramicware,
3.1.1 calibration solutions—4% acetic acid solutions con-
decoratedceramicware,decoratedglass,andleadcrystalglass)
taining known amounts of lead or cadmium which are used to
and is capable of determining lead concentrations greater than
calibrate the instrument.
0.005to0.020µg/mLandcadmiumconcentrationsgreaterthan
0.0005 to 0.002 µg/mL, depending on instrument design.
3.1.2 characteristic mass (m —mass (picograms, pg) of
leadorcadmiumthatproducesinstrumentresponse(peakarea)
1.2 This test method also describes quality control proce-
of 0.0044 integrated absorbance (absorbance-seconds, A-s).
dures to check for contamination and matrix interference
Characteristic mass is a measure of instrument sensitivity and
during GFAAS analyses and a specific sequence of analytical
is a function of instrument design, operating conditions, and
measurements that demonstrates proper instrument operation
analyte-matrix-graphite interactions. Characteristic mass is
during the time period in which sample solutions are analyzed.
calculated from the volume of solution in the furnace and the
1.3 Cleaning and other contamination control procedures
slopeofthecalibrationcurveortheconcentrationthatgivesan
are described in this test method. Users may modify contami-
instrumentresponseinthemiddleoftheworkingrange(thatis,
nation control procedures provided that the modifications
approximately 0.100 or 0.200 A-s). Characteristic mass is
produce acceptable results and are used for both sample and
compared to manufacturer specifications to verify that the
quality control analyses.
instrument is optimized.
1.4 The values stated in SI (metric) units are to be regarded
3.1.3 check solutions—4% acetic acid solutions containing
as the standard. The values given in parentheses are for
known amounts of lead or cadmium which are analyzed in the
information only.
same time period and subjected to the same analytical condi-
1.5 This standard does not purport to address all of the
tions and calibration curve as sample solutions. Check solu-
safety concerns, if any, associated with its use. It is the
tions are analyzed to verify that carry-over did not occur and
responsibility of the user of this standard to establish appro-
the instrument was operating correctly during the time period
priate safety and health practices and determine the applica-
in which sample solutions were analyzed. Portions of calibra-
bility of regulatory limitations prior to use.
tion solutions analyzed as unknown test solutions (as opposed
to analysis for calibrating the instrument) are used for this
purpose.
ThistestmethodisunderthejurisdictionofASTMCommitteeC21onCeramic
Whitewares and Related Productsand is the direct responsibility of Subcommittee
C21.03 on Methods for Whitewares and Environmental Concerns. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2012. Published April 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approvedin2000.Lastpreviouseditionapprovedin2007asC1466–00(2007).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1466-00R12. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1466 − 00 (2012)
3.1.4 dilutionfactor(DF)—factorbywhichconcentrationin 3.1.11 sample concentration limit (SCL)—a low concentra-
test solution is multiplied to obtain concentration in original tion (µg/mL) that can be reliably measured in leach solutions.
leach solution. For test solutions prepared by mixing pipet- In this test method, the sample concentration limit is the
measured portions of leach solution and diluent, DF=(V + concentrationofleadorcadmiumthatproduces0.050A-s.The
V )/V where V and V are volumes of leach solution and value 0.050 A-s is chosen to establish the limit of this test
2 1 1 2
diluentintestsolution,respectively.Fortestsolutionsprepared method for two reasons; 0.050A-s is ten times greater than the
by mixing weighed portions of leach solution (gravimetric maximum response (0.005 A-s) typically expected from
dilution). DF = W /W where: W is the weight of leach periodic, repeated analysis of a contamination-free, 0 ng/mL
T 1 1
solution in test solution and W is the total weight of leach solution and thus guarantees that concentrations in sample
T
solution and diluent in the test solution. solutions are significantly (ten times) greater than those in a
true blank; and percent relative standard deviation of instru-
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
solutions contain 4% acetic acid). Volumetric flasks must be
3.1.14 test solution—solution deposited in the graphite fur-
used when the densities are different (that is, as when diluent
nace for analysis. Test solutions are prepared by diluting leach
contains 4% acetic acid and stock standards contain 2% nitric
solutions with known amounts of 4% acetic acid. Test solu-
acid). Gravimetric dilution is accomplished as follows: weigh
tions also include portions of undiluted leach, check, and
necessary amount (≥1.0000 g) of solution with known concen-
independent check solutions deposited in the furnace.
trationtonearest0.0001ginatared,plasticcontainer.Add4%
3.1.15 working range—range of instrument response that
acetic acid so that weight of final solution provides required
may be described as a linear function of the mass of analyte.
concentration. Calculate concentration in final solution as:
Thelinearrangeofgraphitefurnacepeakareameasurementsis
C 5 C 3W /W (1)
approximately 0.050 to 0.3500-0.400 A-s. The range of linear
2 1 1 2
response depends on the element and operating conditions and
where:
must be verified by analyzing calibration solutions each time
C = concentration in diluted (final) solution, ng/mL;
theinstrumentisused.Thelinearrangeofinstrumentresponse
C = concentration in initial solution, ng/mL;
was chosen as the working range of this method because
W = weight of initial solution, g; and
responses in the linear range are well below those at which
W = weight of final solution, g.
roll-over adversely affects lead and cadmium instrument re-
3.1.7 independent check solution—4% acetic acid solution
sponses obtained using Zeeman background correction.
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
used to prepare calibration solutions. Starting materials with
4.1 Lead and cadmium are extracted from the food-contact
different lot numbers are acceptable, but starting materials
surface of test vessels by filling them with 4% acetic acid to
from different manufacturers are preferable. The independent
within6to7mm( ⁄4in.)ofoverflowingandleachingthemfor
check solution is analyzed to verify that calibration solutions
24 h at 20 to 24°C (68 to 75°F). Lead and cadmium are
have been prepared correctly. An independent check solution
determined by GFAAS using a chemical modifier and instru-
must be used to verify calibration until such time that a
mental background correction. Concentrations in leach solu-
reference material certified for lead and cadmium leaching
tions are calculated using a calibration curve and linear least
becomes available.
squares regression.
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. Concentrationsofleadandcadmiumextractedbyfoodmaybe
C1466 − 00 (2012)
differentfromresultsofthismethod,however,becauseacidity, 7.4 Adjustable Macro- and Micropipettes—Manually oper-
contact time, and temperature typical of consumer use are ated pipets with disposable, colorless, plastic tips and with
different from those of this test method. capacity ranging from 10 µL to 10 mL are acceptable.
Motorized pipets capable of automatic dilution are preferred.
5.2 This test method is intended for application only in
contamination-free settings and should be performed by well- 7.5 Plastic Labware—Use plastic or Teflon labware (gradu-
qualified technical personnel. It is recognized that it is not a atedcylinders,beakers,stirrers,containers,pipettips,autosam-
practical or appropriate method to use in a nonlaboratory plercups)forallproceduresexceptpreparationofintermediate
environment for quality assurance and control of the ceramic lead and cadmium solutions (8.7). Disposable labware that
process. Users are advised to use Test Method C738 (flame does not need precleaning is preferred. When precleaning is
AAS) for purposes of the latter. necessary to eliminate contamination, rinse plastic labware
with 10% (1+9) nitric acid followed by rinsing with copious
6. Interferences quantities of reagent water. Air dry the ware in a dust-free
environment.
6.1 Nonspecificabsorptionandscatteringoflightasaresult
7.6 Glassware—Use new volumetric flasks dedicated for
of concomitant species in leach solutions may produce errone-
ously high results. Instrumental background correction is used use with only this method to prepare intermediate calibration
solutions. Do not use glassware used for other laboratory
to compensate for this interference.
operations because potential for contamination is too great. Do
6.2 Concomitantelementsinleachsolutionsaltertheatomi-
not use glass pipets.Wash new glassware with warm tap water
zation process and thus degrade or enhance instrumental
and laboratory detergent followed by soaking over night in
response. This problem, generally referred to as matrix
10% (1+9) nitric acid and rinsing with copious quantities of
interference, is controlled by diluting leach solutions and by
reagent water. Air dry in dust-free environment. Dedicated
using a chemical modifier and is monitored by calculating
glassware may be reused after rinsing with copious quantities
percent recovery from a fortified (spiked) portion of leach
of reagent water and repeating the acid-cleaning procedure.
solution.
7.7 Gloves, Powder-Free Vinyl—Wear gloves when han-
6.3 Contamination from laboratory glassware, supplies, and
dling test vessels to prevent contamination.
environmental particulate matter (dust) may cause erroneously
high results. Contamination is minimized by keeping work 7.8 Polyethylene Bags, Self-Sealing—Cover or wrap lab-
areas and labware scrupulously clean, using plastic labware warewithnewplasticbagsofsuitablesizetopreventcontami-
whenever possible, using acid-cleaning procedures when glass nation from dust during drying and storage.
labware is required, and protecting samples and supplies from
7.9 Clean-Air Canopy—Laminar flow canopy equipped
dust.Analystsmustestablishcontaminationcontrolprocedures
withhigh-efficiencyparticulatefiltersisrecommendedbecause
before attempting sample analysis because correcting for lead
it makes contamination control easier and analyses faster.
and cadmium contamination that is sporadic (heterogeneous)
Contamination can be controlled, however, without using a
bythepracticeof“blanksubtraction”isnotscientificallyvalid.
clean-aircanopyifcareistakentopreventcontaminationfrom
6.4 Spectral interferences due to direct line overlap are dust.
extremelyrarewhenhollowcathodelampsareusedandarenot
8. Reagents
expected from leach solutions.
8.1 Purity of Reagents—Reagent grade chemicals may be
7. Apparatus
used in all tests provided that they are of sufficiently high
purity to permit their use without lessening the accuracy of the
7.1 Atomic Absorption Spectrometer , capable of displaying
determination. The high sensitivity of graphite furnace may
and recording fast, tran
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