ASTM D8186-18

Standard Test Method for Measurement of Impurities in Graphite by Electrothermal Vaporization Inductively Coupled Plasma Optical Emission Spectrometry (ETV-ICP OES)

SIGNIFICANCE AND USE
5.1 The presence and content of various impurities in graphite are major considerations in determining the suitability of graphite for various applications. This test method provides an alternative means of determining the content of trace impurities in a graphite sample which has considerable advantages compared to classical wet-chemical analysis methods.  
5.2 The test method provides a standard procedure to measure impurities in graphite and to assure required graphite specifications.
SCOPE
1.1 This test method covers the measurement of mass fractions of the elements silver (Ag), aluminum (Al), arsenic (As), boron (B), barium (Ba), berylium (Be), bismuth (Bi), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), sodium (Na), nickel (Ni), phosphorus (P), lead (Pb), sulfur (S), antimony (Sb), silicon (Si), tin (Sn), strontium (Sr), titanium (Ti), vanadium (V), tungsten (W), yitrium (Y), zinc (Zn), and zirconium (Zr) in graphite.  
1.2 Provided that an appropriate validation procedure is carried out, this test method is also applicable to other carbon materials such as coal, coke, carbon black, graphite-felt, graphite-foil, graphite-foam, and fiber reinforced carbon-carbon composites.  
1.3 This test method is applicable to element contents from approximately 0.0001 mg/kg to 1000 mg/kg (0.1 ppmw to 1000 ppmw), depending on element, wavelength, measurement parameters, and sample mass.  
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Sep-2018
• ICS: 71.060.10 - Chemical elements
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.F0 - Manufactured Carbon and Graphite Products

Relations

• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Referred By: ASTM C781-20 - Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components
• Effective Date: 01-Oct-2018
• Referred By: ASTM D7301-21 - Standard Specification for Nuclear Graphite Suitable for Components Subjected to Low Neutron Irradiation Dose
• Effective Date: 01-Oct-2018

Overview

ASTM D8186-18, developed by ASTM International, is the Standard Test Method for Measurement of Impurities in Graphite by Electrothermal Vaporization Inductively Coupled Plasma Optical Emission Spectrometry (ETV-ICP OES). This test method outlines how to accurately determine the mass fractions of various elemental impurities in graphite and related carbon materials. It serves as a significant alternative to classical wet-chemical analysis, offering improved efficiency and reduced risk of contamination and analyte loss.

ETV-ICP OES is a robust technique widely recognized for its capacity to analyze trace levels of impurities-ranging from as low as 0.0001 mg/kg (0.1 ppmw) up to 1000 mg/kg (1000 ppmw)-across a broad spectrum of elements. These include commonly scrutinized impurities such as silver, aluminum, arsenic, boron, barium, beryllium, calcium, iron, lead, sulfur, and many others. The method is applicable both to solid graphite samples and, with proper validation, other related carbon-based materials.

Key Topics

• Impurity Determination: Accurate measurement of trace elemental impurities in graphite materials.
• ETV-ICP OES Technology: Use of electrothermal vaporization for solid sampling coupled with inductively coupled plasma optical emission spectrometry for high-sensitivity detection.
• Broad Elemental Coverage: Determination of over 30 elements including Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr.
• Improved Accuracy: Minimizes sample decomposition steps, thus reducing the potential for contamination and loss of analytes compared to wet-chemical methods.
• SI Units: All results are reported in SI units, ensuring international consistency and comparability.
• Validation: Applicable to other carbon materials (such as coal, coke, carbon black, graphite-felt, graphite-foil, graphite-foam, and carbon composites) upon proper validation.

Applications

ASTM D8186-18 is essential for industries and laboratories where graphite purity is critical:

• Nuclear Energy: High-purity graphite is used as a moderator and reflector; impurity levels can affect reactor safety and efficiency.
• Semiconductors and Electronics: Graphite is a component in various electronic and semiconductor devices; low impurity levels are needed for consistent performance.
• Aerospace and Defense: Graphite composites are used in high-performance components where purity influences mechanical and thermal properties.
• Metallurgy and Chemical Processing: Graphite crucibles, electrodes, and reaction vessels require strict impurity control to prevent unwanted reactions.
• Quality Assurance: Ensures materials meet required specifications, supporting regulatory compliance and customer requirements.

The ETV-ICP OES method provides rapid, direct measurement with minimal sample handling, thus supporting high-volume quality control and routine production analysis.

Related Standards

The following standards and guidelines are frequently referenced or used in conjunction with ASTM D8186-18:

• ASTM D1193: Specification for Reagent Water, ensuring the purity of water used in testing.
• ISO 5725-2: Guidance on accuracy (trueness and precision) of measurement methods and results.
• Certified Reference Materials (e.g., CRM BAM-S009): For calibration and validation of ETV-ICP OES measurements in graphite and similar matrices.
• Other ASTM graphite and carbon analysis standards: For complementary test methods and quality control procedures.

Practical Value

By adopting ASTM D8186-18, laboratories and industry professionals benefit from a standardized, efficient, and sensitive approach to graphite impurity analysis. The test method enhances confidence in graphite quality, supports regulatory and customer compliance, and facilitates international trade by aligning with globally recognized standardization principles. The methodology's flexibility and broad applicability make it a key resource for anyone involved in graphite supply chains and high-purity carbon applications.

Standards Content (Sample)

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: D8186 − 18
Standard Test Method for
Measurement of Impurities in Graphite by Electrothermal
Vaporization Inductively Coupled Plasma Optical Emission
Spectrometry (ETV-ICP OES)
This standard is issued under the fixed designation D8186; 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 the measurement of mass 2.1 ASTM Standards:
fractions of the elements silver (Ag), aluminum (Al), arsenic D1193Specification for Reagent Water
(As), boron (B), barium (Ba), berylium (Be), bismuth (Bi),
2.2 ISO Standards:
calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr),
ISO 5725-2Accuracy (trueness and precision) of measure-
copper(Cu),iron(Fe),potassium(K),lithium(Li),magnesium
ment methods and results—Part 2: Basic method for the
(Mg), manganese (Mn), molybdenum (Mo), sodium (Na),
determination of repeatability and reproducibility of a
nickel (Ni), phosphorus (P), lead (Pb), sulfur (S), antimony
standard measurement method
(Sb), silicon (Si), tin (Sn), strontium (Sr), titanium (Ti),
3. Terminology
vanadium (V), tungsten (W), yitrium (Y), zinc (Zn), and
zirconium (Zr) in graphite.
3.1 Definitions:
3.1.1 ETV, n—electrothermal vaporization.
1.2 Provided that an appropriate validation procedure is
carried out, this test method is also applicable to other carbon
3.1.2 ICP OES, n—inductively coupled plasma optical
materials such as coal, coke, carbon black, graphite-felt,
emission spectrometry.
graphite-foil, graphite-foam, and fiber reinforced carbon-
4. Summary of Test Method
carbon composites.
4.1 The ETVunit consists of an electrically heated graphite
1.3 This test method is applicable to element contents from
tubefurnace.Graphiteboatswhichfitintothegraphitetubeare
approximately 0.0001mg⁄kg to 1000mg⁄kg (0.1ppmw to
1000ppmw), depending on element, wavelength, measure- used for inserting the sample, crushed and milled if necessary,
into the furnace. Handling of graphite boats is preferably done
ment parameters, and sample mass.
using an automated system. One end of the furnace, which is
1.4 The values stated in SI units are to be regarded as
sealed with a movable door, is used for inserting the graphite
standard. The values given in parentheses after SI units are
boats (furnace inlet). The other end of the furnace (furnace
provided for information only and are not considered standard.
outlet) is connected via a tube to the injector tube of the
1.5 This standard does not purport to address all of the
ICP-torch. The graphite tube furnace is heated rapidly to a
safety concerns, if any, associated with its use. It is the
temperaturewhereevaporationofanalyteelementstakesplace.
responsibility of the user of this standard to establish appro-
Forcompletevolatilizationofanalyteelements,ahalogenating
priate safety, health, and environmental practices and deter-
reaction gas is added to the argon carrier gas stream. The
mine the applicability of regulatory limitations prior to use.
evaporation products containing the analyte elements are
1.6 This international standard was developed in accor-
transported as dry aerosol with the argon carrier gas stream
dance with internationally recognized principles on standard-
fromthefurnaceoutlettotheICP-torchwheretheyareexcited
ization established in the Decision on Principles for the
toemitopticalradiation.Theemittedradiationisdispersedand
Development of International Standards, Guides and Recom-
detected by a simultaneous spectrometer. The intensity of
mendations issued by the World Trade Organization Technical
radiation of emission lines and background (optional) is
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D02 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee D02.F0 on Manufactured Carbon and Graphite Products. the ASTM website.
Current edition approved Oct. 1, 2018. Published December 2018. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D8186-18. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8186 − 18
measured with appropriate detectors.The mass fractions of the vaporize these elements. In addition, aerosols formed by
analyte elements are calculated by comparing the intensities of pyrolysis of the reaction gas act as condensation nuclei for
the element-specific spectral lines of the sample with calibra- sample vapors, which have a positive effect on transport
tion samples of known analyte content. efficiency(seeRefs (1-3), (5-7)).Tomeasureallelementslisted
in 1.1, dichlorodifluoromethane (CCl F ) shall be used as
2 2
4.2 For ICP OES, sample introduction is usually done by
reaction gas. Using other reaction gases (for example, CF ,
nebulization of liquids. In the case of graphite, sample decom-
CCl F , CHF , CHClF,C H F,SF , and NF ) may result in
2 2 3 2 2 2 4 6 3
position prior to analysis is required, for example, by ashing,
reduced release of some analytes from the graphite matrix.
melt-fusion, or acid/pressure-decomposition. These decompo-
sition procedures are time-consuming, and the possibility of
4.5 The dry aerosol is transported by means of suitable
introductionofimpuritiesaswellasanalytelossesrepresentsa
tubing to the injector tube of the plasma torch of the ICP
serious source of systematic errors. In ETV-ICP OES, sample
spectrometer where it is excited to emit optical radiation (see
introduction by nebulization of liquids is replaced by the
Fig. 3).
electrothermal vaporization of solid samples at high tempera-
4.6 A description of possible interferences and their elimi-
tures in a graphite tube furnace, thus eliminating the need for
nation is given in Appendix X2.
wet chemical sample decomposition prior to analysis. In
general, ETV-ICP OES provides a linear working range of up
5. Significance and Use
tofourordersofmagnitude.Thisrangecanbeexpandedforthe
respective elements by selecting emission lines with different
5.1 The presence and content of various impurities in
sensitivity or variation of sample mass, or both.
graphitearemajorconsiderationsindeterminingthesuitability
of graphite for various applications. This test method provides
4.3 AprerequisiteforETV-ICPOESisanefficienttransport
an alternative means of determining the content of trace
of the gaseous products generated in the graphite tube furnace
impurities in a graphite sample which has considerable advan-
during the heating step to the ICP-torch. This is achieved by a
tages compared to classical wet-chemical analysis methods.
suitable graphite tube design and gas regime in the transition
area between the graphite tube and transport tube as shown in
5.2 The test method provides a standard procedure to
Figs.1and2.SeealsoRefs (1-4). Anozzle-typegraphitetube
measure impurities in graphite and to assure required graphite
and the use of a bypass-gas in the gap between the graphite
specifications.
tube and transport tube are the key factors for high and
reproducible transport efficiencies as well as minimized matrix
6. Apparatus
effects. The temperature of the graphite tube furnace in the
6.1 Laboratoryinstrumentsarerequiredasdetailedin6.2to
evaporation step depends on the analytes to be determined.
6.8. In the case of the spectrometer (6.2) and the ETV system
Release of volatile analytes (such as arsenic, cadmium,
(6.3), the user shall follow the manufacturer’s instructions on
potassium,lithium,andsodium)fromthegraphitematrixstarts
use of the apparatus.
at 500°C to 800°C. To measure all elements listed in 1.1 a
temperature of 2600°C is required.
6.2 Inductively Coupled Plasma Optical Emission
Spectrometer—A simultaneous method capable of recording
4.4 By addition of a halogen-containing reaction gas to the
transient emission signals, suited to synchronize data acquisi-
carrier gas, the vaporization temperatures of elements are
tion with an ETV heating cycle.
lowered through the formation of volatile halides. In the case
NOTE 1—In ETV-ICP OES, the evaporating sample may cause a
of carbide-forming elements, halogenation is a prerequisite to
significant alteration to the spectral background near the emission lines,
which increases the measurement uncertainty. This effect can be reduced
if the spectrometer is capable of measuring the intensity of emission lines
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. and the intensity of spectral background close to the emission lines
FIG. 1 ETV Unit: Schematic Design of Gas Flows
Key:
1 Graphite tube with graphite boat and sample
2 Transition area between graphite tube and transport tube
3 Transport tube
4 Carrier gas (argon)
5 Reaction gas (CCl F )
2 2
6 Furnace shield gas (argon)
7 Bypass gas (argon)
8 Dry aerosol to injector tube of plasma torch
D8186 − 18
FIG. 2 ETV Unit: Schematic Design of Graphite Tube and Transition Area
Key:
1 Graphite tube
2 Transition area
3 Nozzle of graphite tube
4 Transition tube (alumina)
5 Carrier gas (argon)
6 Reaction gas (CCl F )
2 2
7 Bypass gas (argon)
8 Gas-mixture and dry sample aerosol to injector tube of plasma torch
FIG. 3 Schematic Design of ETV Unit and Coupling to ICP
Key:
1 Graphite tube furnace
2 Graphite tube with graphite boat
3 Graphite contacts
4 Transition area
5 Furnace inlet with movable door
6 Pyrometer for online temperature measurement
7 Electrical power supply
8 Carrier gas (argon) and reaction gas (CCl F )
2 2
9 Furnace shield gas (argon)
10 Bypass gas (argon)
11 Transition tube (alumina)
12 Tubing to injector tube of ICP torch
13 Injector tube of ICP torch
14 ICP torch
simultaneously. For method development, it is beneficial if the spectrom-
and high transport efficiency, heat resistant tubing (up to
eter is capable of recording emission signal intensities versus time
150°C) to connect the ETV system with the ICP-torch,
(so-called “time-scan”).
interface for synchronizing the ETV system with the ICP
6.3 Electrothermal Vaporization System—With an electri-
spectrometer.
callyheatedgraphitetubefurnace,graphiteboats,reproducible
NOTE 2—Reproducibility of analysis results can be improved using an
setting and continuous control of temperatures up to 2600°C
automated handling system for the graphite boats (autosampler). An
(tolerance 650°C), programmable temperature versus time autosampler also increases sample throughput and saves working time.
runs, controlled gas flows (preferably mass-flow controlled),
6.4 Balance—Capable of weighing to the nearest 0.01mg.
graphite tube design and transition area between graphite tube
and transport tube optimized in terms of dry aerosol formation 6.5 Tweezers.
D8186 − 18
6.6 Microspatula. 9. Preparation of Apparatus
9.1 ICP OES—Consult the manufacturer’s instructions for
6.7 Crusher or Mill—Material adapted to the analytical
the operation of the inductively coupled plasma optical emis-
task.
sion spectrometer.
6.8 DryingApparatus—Suitableforcontamination-freedry-
9.2 ETV System—Consult the manufacturer’s instructions
ing of calibration solutions pipetted into the graphite boats, a
for the operation of the electrothermal vaporization system.
drying temperature of maximum 100°C, and heating of
Before use, the graphite boats must be cleaned by thermo-
graphite boats from both sides.
halogenationinthegraphitetubefurnaceoftheETVsystemat
6.8.1 Ensure that possible contamination originating from
atemperaturenotlowerthanthevaporizationtemperatureused
laboratory instruments has no effect on the accuracy of the
for sample analysis.
analysis results.
9.3 Operating Parameters for ICP OES and ETV System—
7. Reagents and Materials
For materials other than graphite, these parameters must be
evaluated as part of method development for each specific
7.1 PurityofReagents—Reagentsofknownanalyticalgrade
material.Appropriateoperatingparametersshallbeestablished
shall be used, provided it is first ascertained that the reagent is
using calibration samples, preferably certified reference mate-
of sufficiently high purity to permit its use without compro-
rials.Thereleasebehaviorofeachanalyteshallbeinvestigated
mising the accuracy of the determination.
by recording the intensity of the used emission lines versus
7.2 Sample Boats—Made out of low-porosity or
time (so called “time-scan”).
pyrolytically-coated high-purity graphite, the size adapted to
NOTE6—Foroperatingparametersfortheanalysisofgraphite,see11.6.
the graphite tube of the ETV-furnace.
10. Calibration
NOTE 3—With low-porosity or pyrolytically-coated graphite sample
boats, diffusion of calibration solution through the sample boat can be
10.1 Calibration shall be performed prior to each measure-
avoided.
ment cycle. Calibration solutions and calibration samples with
7.3 Reaction Gas—Dichlorodifluoromethane (CCl F ).
2 2 defined analyte concentrations and contents, respectively, shall
NOTE 4—The use of ozone-depleting substances such as CCl F is
2 2 be measured applying the same measurement parameters and
restricted under the CleanAirAct. For laboratory and research purposes,
procedure as for the unknown sample (see Section 11). For
however, the use of CCl F is still allowed. Complete thermal decompo-
2 2
each element, the calibrated range shall be adjusted to the
sition of CCl F is achieved in the hot graphite tube furnace and in the
2 2
content of this element in the unknown sample. This is
inductively-coupled plasma.
achieved by using (i) different volumes of the same calibration
7.4 Water—Comply with grade II of ASTM Specification
solution,(ii)differentmassesofthesamecalibrationsampleor
D1193.
calibration solutions, and (iii) calibration samples with differ-
7.5 Calibration Solutions—Aqueous single- or multi-
ent analyte element concentrations.
element calibration solutions, prepared by dilution of commer-
10.2 Calibration shall be done using:
cially available standard-stock solutions with water to the
(a)Calibration samples of the same material as the un-
required concentration.
known sample, preferably certified reference materials (CRM,
7.6 Calibration Samples—With defined mass fractions of see Appendix X3) or matrix-adapted synthetic calibration
impurities, preferably certified reference materials (CRM). samples.
NOTE 5—A commercially available CRM is listed in Appendix X3. (b)Aqueous single- or multi-element calibration solutions
which are pipetted into the graphite boats and then dried in the
7.7 Argon—Purity ≥ 99.996 (volume fraction).
drying apparatus (6.8) (see (8, 9) and Appendix X4). Calibra-
tion using dried calibration solutions shall be validated by the
8. Sampling and Sample Preparation
analysis of suitable CRMs or by comparison of the analysis
8.1 Sampling shall be representative of the graphite grade
results with those obtained by independent analysis methods.
lots and billets. If the dry state of the graphite is not secured,
(c)A mix of (a) and (b).
the sample must be dried at 110°C 6 5°C until there is no
10.2.1 The calibration with aqueous standard solutions can
changeinmassandthenstoredinadesiccator.Inhomogeneous
bematrix-adaptedusingmaterialsofthesamecompositionbut
sample materials must be homogenized.
with analyte contents known, based on independent methods,
tobenegligibletothoseexpectedintheunknownsample.This
8.2 Graphite blocks shall be crushed or sawed into small
so-calledblanksampleisweighedintothegraphiteboat(same
pieces which fit into the graphite boats or milled to graphite
massasunknownsample),andtheaqueousstandardsolutionis
powder. Alternatively, a powder sample may be drilled out of
added and then dried in the drying apparatus.
the graphite block (graphite foil and graphite felt shall be
rippedintosmallpieces,forexample,usingtweezers,whichfit 10.3 Depending on the sample material, release of the
into the graphite boats). Standard apparatus and procedures for elementsboronandsiliconinthegraphitetubefurnaceandthe
sample preparation may be used provided that no contamina- efficiency of their transport to the ICP may be reduced, which
tion occurs which affects the accuracy of the determination. would lead to a result that lies below the actual value (see
Special attention should be paid to contamination control if Section 15).To avoid this systematic error, the elements boron
high-purity graphite materials are analyzed. and silicon shall be calibrated using calibration samples of the
D8186 − 18
same material (with respect to raw materials, manufacturing, 11.4 At the selected sample mass, the measured emission
and morphology) as the unknown sample. If such calibration intensitiesoftheanalytesshallbewithinthelinearrangeofthe
samples are not available, the trueness/percentage recovery of calibration functions.
results must be validated using independent test methods.
11.5 The blank value shall be measured using empty and
Trueness is a measure of how close the measured element
cleanedgraphiteboats.Agraphiteboatcontainingacalibration
content is to the real element content in the graphite sample.
sample or a dried calibration solution shall be used to verify
Percentage recovery is an alternative measure of trueness
that the measuring position for the selected emission lines and
defined as (measured element content/real element content
background is at optimum position.
×100).
11.6 The graphite boats are inserted into the graphite tube
10.3.1 The release and transport of boron can be improved
furnaceoftheETV-unitbymeansoftweezersoranautomated
by addition of a suitable matrix modifier to the sample.
sample changer. To avoid errors due to memory effects, the
Aqueous solutions of potassium hydroxide (KOH) or sodium
calibration samples shall be measured in ascending analyte
hydroxide(NaOH),forexample,showthiseffect.Themodifier
concentrations. For analysis, the temperature-time program of
solution is pipetted onto the graphite sample in the graphite
the ETV-unit and the registration of the emission signals at the
boat and then dried using the drying apparatus (6.8).
spectrometer shall be started simultaneously.At the end of the
10.4 The data obtained by measurement of calibration
analysis program the graphite boat is removed from the
samples shall be used to establish a calibration function for
graphite tube furnace and the next graphite boat is inserted.
each element. The procedure for this shall follow the instruc-
This procedure is repeated until all calibration samples and
tions of the manufacturer of the spectrometer. Usually, the
unknown samples are measured.
operating software of the spectrometer allows different regres-
11.6.1 Predefined ETVprogram for the determination of all
sionmodels.Foreachelement,theregressionmodelshouldbe
the elements indicated in the Scope:
selectedaccordingtotheresponseoftheemissionsignaltothe
absoluteelementmassvaporizedinthevaporizationstepofthe
Gas flow rates: Furnace shield gas 500 mL/min
ETV program. As ETV-ICP OES usually provides a linear
(argon)
working range of up to four orders of magnitude, linear Carrier gas (argon) 150 mL/min
Bypass gas (argon) 350 mL/min
regression can be applied in most cases to establish the
Modifier gas (CCl F ) 2.0 mL/min
2 2
calibration function.
Step 1 (pretreatment) Ramp 25 °C to 450 °C, 7 s
Hold 450 °C, 10 s
11. Procedure
Step 2 (vaporization) Ramp 450 °C to 2600 °C, 5 s
Hold 2600 °C, 20 s
11.1 Before analysis, a cleaning cycle shall be performed
Step 3 (cooling)
with empty graphite boats (see 9.2).
11.2 Calibration samples and unknown samples (prepared
as described in Section 8) shall be weighed into cleaned
11.6.2 Spectrometer integration interval: 17s to 45s after
graphite boats. The mass shall be recorded. Calibration solu-
starting the furnace program (total signal integration time of
tionsshallbepipettedintothecleanedgraphiteboatsanddried
28s).
at a temperature below the boiling point of the calibration
11.6.3 The cooling time depends of the cooling system of
solution in the drying equipment (6.8). The pipetted volume
thefurnace.Thegraphiteboatshouldbechangedatatempera-
shall be recorded.
ture below 200°C.
11.3 If an automated sample changer is used, the graphite 11.6.4 Coarse-grained samples or pieces may lead to a
delayed thermal release of some analytes which can be
boatsshallbeplacedonthesamplerackinthefollowingorder:
calibration solutions–calibration samples (both in ascending recognized by a tailing of the transient analyte emission
signals. Tailing can be reduced by: (1) increase of the vapor-
analyte mass)–unknown samples.
ization temperature and/or vaporization time, (2) addition of a
11.3.1 Depending on analyte element, analyte content, se-
matrix modifier, and (3) milling of the samp
...