ASTM C1466-00(2020)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1466 − 00 (Reapproved 2020)
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 mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers procedures for using graphite
furnace atomic absorption spectroscopy (GFAAS) to quantita-
2. Referenced Documents
tively determine lead and cadmium extracted by acetic acid at
2.1 ASTM Standards:
room temperature from the food-contact surface of foodware.
Themethodisapplicabletofood-contactsurfacescomposedof C738Test Method for Lead and Cadmium Extracted from
Glazed Ceramic Surfaces
silicate-based materials (earthenware, glazed ceramicware,
decoratedceramicware,decoratedglass,andleadcrystalglass)
3. Terminology
and is capable of determining lead concentrations greater than
0.005to0.020µg/mLandcadmiumconcentrationsgreaterthan
3.1 Definitions of Terms Specific to This Standard:
0.0005 to 0.002 µg/mL, depending on instrument design.
3.1.1 calibration solutions—4% acetic acid solutions con-
taining known amounts of lead or cadmium which are used to
1.2 This test method also describes quality control proce-
calibrate the instrument.
dures to check for contamination and matrix interference
during GFAAS analyses and a specific sequence of analytical
3.1.2 characteristic mass (m —mass (picograms, pg) of
measurements that demonstrates proper instrument operation
leadorcadmiumthatproducesinstrumentresponse(peakarea)
during the time period in which sample solutions are analyzed.
of 0.0044 integrated absorbance (absorbance-seconds, A-s);
characteristicmassisameasureofinstrumentsensitivityandis
1.3 Cleaning and other contamination control procedures
a function of instrument design, operating conditions, and
are described in this test method. Users may modify contami-
analyte-matrix-graphite interactions; characteristic mass is cal-
nation control procedures provided that the modifications
culated from the volume of solution in the furnace and the
produce acceptable results and are used for both sample and
slopeofthecalibrationcurveortheconcentrationthatgivesan
quality control analyses.
instrumentresponseinthemiddleoftheworkingrange(thatis,
1.4 The values stated in SI units are to be regarded as
approximately 0.100 or 0.200 A-s); characteristic mass is
standard. The values given in parentheses after SI units are
compared to manufacturer specifications to verify that the
provided for information only and are not considered standard.
instrument is optimized.
1.5 This standard does not purport to address all of the
3.1.3 check solutions—4% acetic acid solutions containing
safety concerns, if any, associated with its use. It is the
known amounts of lead or cadmium which are analyzed in the
responsibility of the user of this standard to establish appro-
same time period and subjected to the same analytical condi-
priate safety, health, and environmental practices and deter-
tionsandcalibrationcurveassamplesolutions;checksolutions
mine the applicability of regulatory limitations prior to use.
are analyzed to verify that carry-over did not occur and the
1.6 This international standard was developed in accor-
instrument was operating correctly during the time period in
dance with internationally recognized principles on standard-
which sample solutions were analyzed; portions of calibration
ization established in the Decision on Principles for the
solutions analyzed as unknown test solutions (as opposed to
Development of International Standards, Guides and Recom-
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 Nov. 1, 2020. Published December 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2000. Last previous edition approved in 2016 as C1466–00(2016). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/C1466-00R20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1466 − 00 (2020)
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: (1) 0.050A-s is ten times greater than
by mixing weighed portions of leach solution (gravimetric the 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 (2) percent relative standard deviation of
3.1.5 fortified leach solution—a portion of leach solution to
instrument response (relative variability as a result of instru-
whichaknownamountofleadorcadmiumisadded;afortified
ment precision) is better for 0.050 A-s than for lower values;
leach solution is analyzed to calculate percent recovery and
the sample concentration limit depends on the characteristic
monitor matrix interference; stock, intermediate, and calibra-
massoftheinstrumentandvolumeofsolutiondepositedinthe
tion 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
solutionswithknownamountsof4%aceticacid;testsolutions
acid); gravimetric dilution is accomplished as follows: weigh
also include portions of undiluted leach, check, and indepen-
necessary amount (≥1.0000 g) of solution with known concen-
dent 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, and calculate concentration in final solution as:
the linear range of graphite furnace peak area measurements is
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,
the instrument is used; the linear range of instrument response
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 (2020)
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—Weargloveswhenhandling
6.3 Contamination from laboratory glassware, supplies, and
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-airCanopy—Laminarflowcanopyequippedwith
dust.Analystsmustestablishcontaminationcontrolprocedures
high-efficiency particulate filters is recommended because it
before attempting sample analysis because correcting for lead
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
used in all tests provided that they are of sufficiently high
7. Apparatus
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, transient signals, measuring peak area, and
require reagents of higher purity than reagent grade. At a
havingsensitivity(m basedonpeakarea)lessthanorequalto
minimum, all reagents must conform to the specifications of
30-pg lead and 1.3-pg cadmium when wavelengths 283.3 and
theCommitteeonAnalyticalReagentsoftheAmericanChemi-
228.8 nm are used for lead and cadmium determinations,
cal Society when such specifications are available.
respectively, equipped with light sources (hollow cathode or
8.2 Reagent Water—Ultrapure, deionized, resistance
electrodeless discharge lamps) specific for lead and cadmium,
≥18megohm-cm.
instrumental background correction (deuterium arc, Zeeman,
or pulsed techniques such as Smith-Hieftje), autosampler, and
electrothermal atomizer (graphite furnace) with pyrolytically
The sole source of supply of the apparatus known to the committee at this time
isPolypropylenecentrifugetubeswithcaps,50mLcapacity(ItemNo.2068,Becton
coated tubes and platforms. Use wavelengths of 283.3 and
Dickinson and Co., Franklin Lakes, NJ). If you are aware of alternative suppliers,
228.8 nm for lead and cadmium, respectively. Record instru-
please provide this information to ASTM International Headquarters. Your com-
mentresponseaspeakarea(A-s).Donotusepeakheight.Peak
ments will receive careful consideration at a meeting of the responsible technical
area compensates for small differences in peak shape an committee, which you may attend.
The sole source of supply of the apparatus known to the committee at this time
appearance time that occur in leach and calibration solutions.
is Micro Cleaner, a trademark of International Products Corp., Burlington, NJ,
7.2 Gas Supply for Furnace, high purity (99.99%) argon. (Catalogue No. 6731). If you are aware of alternative suppliers, please provide this
information to ASTM International Headquarters. Your comments will receive
7.3 Cooling Water for Furnace—Use device that controls
careful consideration at a meeting of the responsible technical committee, which
temperature and recirculates coolant. you may attend.
C1466 − 00 (2020)
8.3 Detergent Solution for Cleaning Samples (0.02 %, by 9.3 Immediately cover vessels to minimize evaporation.
Volume)—Mix 1 mL detergent with 5 L tap water. Use Useopaquematerialorplacevesselindarklocationtoprevent
photo-oxidation of insoluble cadmium sulfide to soluble cad-
nonacidic, liquid detergent designed for washing household
mium sulfate.
dishes by hand. Do not use chemicals or detergents designed
for cleaning labware because such detergents may damage the
9.4 Leach vessels for 24 h at 22 6 2 °C.
ware.
9.5 At 24 h, visually observe level of leach solutions. If
evaporativelosseshaveoccurred,add4%aceticacidtowithin
8.4 Acetic Acid (4 % by Volume)—Mix one volume glacial
6 to 7 mm of the edge of vessel. Proceed immediately to next
acetic acid with 24 volumes reagent water. Prepare a quantity
section.
sufficient for leaching samples and preparing calibration and
check solutions.
9.6 Gently stir leach solutions with plastic device and
transfer by pipet to plastic container. Do not pour. For best
8.5 Matrix Modifier Solution (1 %, w/v, NH H PO )—
4 2 4
results, analyze within one day. Leach solutions with no
Dissolve 0.5 g ammonium dihydrogen phosphate in 50 mL
precipitatemaybeheldlongerifstoredincleancontainerswith
−3
reagent water. One µLcontains 8.3 µg phosphate ion (PO ).
tightly sealed caps. Store in total darkness until analysis.
8.5.1 Optional Matrix Modifier Solution for Instruments
9.7 Precipitated matter, if present, may be removed from
with Zeeman Background Correction (1 %, w/v, NH H PO
4 2 4
leach solutions by filtering with PTFE filters in natural (not
with 0.4 %, w/v, Mg—Dissolve 2.1 g magnesium nitrate hexa-
colored) polypropylene housings attached to polypropylene
hydrate (Mg(NO ) ·6H O) in 50 mL of phosphate modifier
3 2 2
syringes. Acid clean filters and syringes with 4% acetic acid
solution. One µL of optional modifier contains 8.3 µg phos-
immediately before use.
phate ion and 4.0 µg magnesium ion.
10. Instrument Optimization
8.6 Stock Lead and Cadmium Solutions—Use 1000 or
10000µg⁄mL single-element stock solutions in 2 to 10%
10.1 Optimize spectrometer settings, furnace program, and
nitric acid prepared specifically for spectrometric analysis. Do
mass of chemical modifier for each element so that character-
not use solutions containing hydrochloric, sulfuric, or phos- istic mass of lead and cadmium is within approximately
phoric acid. Multi-element solutions may be used to prepare 620% of manufacturer specifications, precision of ten mea-
surements is ≤5 % (preferably ≤3 %) relative standard
independent check solutions. Commercially prepared stock
deviation,andatomizationpeaksaresymmetricallyshapedand
solutions are recommended.
centered in a window of approximately 5 s. Instruments with
8.7 Intermediate Lead and Cadmium Solutions—Transfer
multi-elementcapabilitymaybeoptimizedforoneelementand
by pipet ≥1000 µL stock solution to acid-cleaned volumetric
used with compromised conditions for determination of the
flask and dilute to ≥100.0 mL with 4% acetic acid.
other element if quality control measurements are acceptable.
Begin the optimization process by using 20 µL of a lead
8.8 Calibration and Independent Check Solutions—Prepare
calibration solution (10 µL of a cadmium calibration solution)
calibration solutions that produce responses of 0.000 A-s
that produces approximately 0.100 or 0.200 A-s and furnace
(0ng⁄mL) and approximately (620%) 0.050, 0.100, 0.200,
program recommended by manufacturer. Optimize dry, char,
and 0.350 to 0.400A-s. Prepare an independent check solution
atomization,andcleanstepsofthefurnaceprogramasfollows.
that produces approximately 0.300 A-s. Preparation of a
Dry: determine highest temperature and shortest time required
calibration solution that produces approximately 0.300 A-s is
to evaporate solution without spattering. Char: determine
optional. Use of gravimetric dilution or pipets with disposable,
highest temperature at which no loss of atomic absorbance
plastic tips is recommended. Do not use glass volumetric
(peak
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