ASTM E1097-12(2017)

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: E1097 − 12 (Reapproved 2017)
Standard Guide for
Determination of Various Elements by Direct Current
Plasma Atomic Emission Spectrometry
This standard is issued under the fixed designation E1097; 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
2.1 ASTM Standards:
1.1 This guide covers procedures for using a Direct Current
Plasma Atomic Emission Spectrometer (DCP-AES) to deter- E29Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
mine the concentration of elements in solution. Recommenda-
tionsareprovidedforpreparingandcalibratingtheinstrument, E50Practices for Apparatus, Reagents, and Safety Consid-
erations for Chemical Analysis of Metals, Ores, and
assessing instrument performance, diagnosing and correcting
for interferences, measuring test solutions, and calculating Related Materials
E135Terminology Relating to Analytical Chemistry for
results. A method to correct for instrument drift is included.
Metals, Ores, and Related Materials
1.2 This guide does not specify all the operating conditions
E882Guide for Accountability and Quality Control in the
for a DCP-AES because of the differences between models of
Chemical Analysis Laboratory
these instruments. Analysts should follow instructions pro-
E1601Practice for Conducting an Interlaboratory Study to
vided by the manufacturer of the particular instrument.
Evaluate the Performance of an Analytical Method
1.3 Thisguidedoesnotattempttospecifyindetailallofthe
hardware components and computer software of the instru-
3. Terminology
ment. It is assumed that the instrument, whether commercially
3.1 Definitions: For definitions of terms used in this guide,
available, modified, or custom built, will be capable of per-
refer to Terminology E135.
forming the analyses for which it is intended, and that the
3.2 Definitions of Terms Specific to This Standard:
analyst has verified this before performing the analysis.
3.2.1 background equivalent concentration (BEC), n—in
1.4 This standard does not purport to address all of the
DCP-AES,theanalyteconcentrationwhosesignalisequivalent
safety concerns, if any, associated with its use. It is the
to the signal generated by the plasma and matrix at the analyte
responsibility of the user of this standard to establish appro-
line when the actual analyte concentration is zero.
priate safety and health practices and determine the applica-
3.2.2 detection limit (DL), n—in addition to the DL defined
bility of regulatory limitations prior to use. Specific precau-
in Terminology E135, the following detection limits are
tionary statements are given in Section 7.
described and used in this guide:
1.5 This international standard was developed in accor-
3.2.2.1 instrumental detection limit (IDL), n—in DCP-AES,
dance with internationally recognized principles on standard-
the analyte concentration corresponding to three times the
ization established in the Decision on Principles for the
standarddeviationofthebackgroundnoisebeneaththeanalyte
Development of International Standards, Guides and Recom-
line on a set of nine consecutive 10-s measurements of the
mendations issued by the World Trade Organization Technical
background intensity of the blank.
Barriers to Trade (TBT) Committee.
3.2.2.2 method detection limit (MDL), n— in DCP-AES, the
detection limit measured on the matrix blank.
This guide is under the jurisdiction of ASTM Committee E01 on Analytical
ChemistryforMetals,Ores,andRelatedMaterialsandisthedirectresponsibilityof
Subcommittee E01.20 on Fundamental Practices. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2017. Published June 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1986. Last previous edition approved in 2012 as E1097–12. DOI: Standardsvolume information, refer to the standard’s Document Summary page on
10.1520/E1097-12R17. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1097 − 12 (2017)
3.2.3 equivalent analyte concentration, n—the apparent concentration. Prepare a quantity sufficient to clean the end of
concentration of an interfering element on an anlalyte. the sample uptake tubing and to flush the sample introduction
systembetweeneachdeterminationofcalibrationsolutionsand
3.2.4 linear dynamic range, n—the concentration range
test solutions. Occasionally, an analyte requires a conditioning
fromthelimitofquantificationtothehighestconcentrationthat
timeintheaspiration/nebulizationsystemoftheinstrument.In
remains within 6 10% of linearity based on lower concentra-
this case, use the test solution as a rinse and allow a sufficient
tions.
residence time before taking a reading.
3.2.5 limit of quantification (LOQ), n—the lowest concen-
tration at which the instrument can measure reliably with a 6.3 Reagent Blank Solution—This solution consists of all
defined error and confidence level.
reagents and other additions at the same concentration used in
preparing the test solution. Carry this solution through the
3.2.6 sensitivity, n—the slope of the analytical curve, which
entire sample preparation procedure.
is the ratio of the change in emission intensity to the change in
concentration.
6.4 Matrix Blank Solution—Prepare this solution to be as
close in composition to the test solution as possible (including
4. Summary of Guide
dissolution reagents and matrix elements), but omitting the
4.1 Direct Current Plasma atomic emission spectrometers,
elements to be determined. The matrix elements should be of
eithersimultaneousorsequential,measuretheconcentrationof
high purity.
elements in solution. Samples, calibration and other solutions
6.5 Control—Selectareferencematerialorothermaterialof
arenebulizedandtheaerosolistransportedtothedirectcurrent
known composition and prepare it as directed in the test
plasma jet where excitation occurs and characteristic emission
method. Analyze the control regularly as a blind sample and
spectra are produced. The spectra are dispersed by an echelle
use the results for quality control as directed in Guide E882.
grating and cross-dispersed by a prism or grating. The spectra
then impinge on photomultiplier tubes, whose outputs are
6.6 Calibration Solutions—The number and type of these
interpreted by a microprocessor/PC as emission intensities.
solutions will depend on the method, and on the type of
Background correction can be used to compensate for some
DCP-AES instrument and its microprocessor/PC. Generally,
interferences. The microprocessor/PC generates calibration
prepare two instrument calibration solutions, one high
curves and calculates analyte concentration.
concentration, and one low concentration or a blank, that
bracket the expected concentration range of the sample test
5. Significance and Use
solutions. More may be prepared if the microprocessor/PC can
5.1 Analyses using DCP-AES require proper preparation of
utilize them, especially if the analyte composition of the test
test solutions, accurate calibration, and control of analytical
solutionsisexpectedtocoverawiderangeorifthecalibration
procedures. ASTM test methods that refer to this guide shall
curve is non-linear. Prepare the calibration solutions by adding
provide specifics on test solutions, calibration, and procedures.
aliquotsfromstocksolutionstosolutionsthataresimilartothe
5.2 DCP-AES analysis is primarily concerned with testing matrix of the test sample.
materials for compliance with specifications, but may range
6.6.1 Match the matrix of the calibration solutions as
from qualitative estimations to umpire analysis. These may
closely as possible to that of the test solution in acidity, total
involve measuring major and minor constituents or trace
solids, reagents, and matrix elements, especially if easily
impurities, or both. This guide suggests some approaches to
ionizedelements(EIE)arepresent.Somematrixelementsmay
these different analytical needs.
be eliminated if it can be shown by spike addition or standard
additions that the effect on the test solution analytes is
5.3 This guide assists analysts in developing new methods.
insignificant.Usestocksolutionsorpureelementspreparedby
5.4 It is assumed that the users of this guide will be trained
amethodsimilartothatusedtopreparethetestsolutions.Ifthe
analysts capable of performing common laboratory procedures
composition of the test solution is unknown to the extent that
skillfully and safely. It is expected that the work will be
matrix-matched solutions cannot be prepared, or if a suffi-
performed in a properly equipped laboratory.
ciently pure matrix material is not available, refer to the
5.5 This guide does not purport to define all of the quality
method of standard additions described in 6.7 and 10.6.
assurance parameters necessary for DCP-AES analysis. Ana-
NOTE 1—If the instrument is designed to use a blank as the low
lysts should ensure that proper quality assurance procedures
concentration calibration solution, prepare it the same way as the high
arefollowed,especiallythosedefinedbythetestmethod.Refer
concentration calibration solution is prepared, omitting the elements to be
to Guide E882.
determined. Where matrix-matched calibration solutions are employed,
this will be the matrix blank solution.
6. Preparation of Solutions
6.6.2 Optimum Calibration Solution Concentration
6.1 Solutions are prepared for different purposes. Not all
Range—Forcalibrationinthelinearrange,thehighestconcen-
maybenecessaryforeverytest.Prepareonlythosedirectedby
tration should be no more than 85% of the upper limit of the
the method or required to meet specific experimental objec-
calibrationcurvelinearity.Foraninstrumentthatacceptsalow
tives.
concentration calibration solution, its concentration should be
6.2 Rinse Solution—Prepare a rinse solution to contain the at least four times the method detection limit and above the
acids or bases present in the test solution at the same limit of quantification (LOQ).
E1097 − 12 (2017)
6.7 Standard Additions Solutions—Prepare as directed in surements when required, that the daily performance of the
either 6.7.1 or 6.7.2 as follows: instrument meets the criteria of the method.
6.7.1 Prepare four separate test solutions of the sample. To
8.1.2 When adapting a documented test method for the first
all but one, add known amounts of the analyte equal to (0.5, time, confirm that freedom from interferences, linearity, DL,
1.0, and 1.5) times or (1.0, 2.0, and 3.0) times the expected
LOQ and sensitivity meet the criteria of the method.
concentrationoftheanalyte(s)inthetestsolution.Theoriginal
8.1.3 For lists of wavelengths and information on their
3 4 5 6
analyte concentration must be at or above it’s LOQ. The final
characteristics, refer to Harrison, Meggers, Phelps, Reader,
analyte concentration in the highest spike must not be greater or Winge.
than the linear range of the emission line used. Dilute all
8.1.3.1 In the laddered array of spectra from the DCP’s
solutions to the mark and mix. Prepare an equal volume of the
echelle grating, some wavelengths appear in two adjacent
reagent blank solution when using 10.6.2.
orders. These wavelengths usually have similar intensities.
6.7.2 Transfer four equal volumes of a test solution to four
Occasionally, one may prove more useful for a specific
volumetric flasks of the same size. To all but one, add known
application.
amounts of the analyte equal to 0.5, 1.0, and 1.5, or 1.0, 2.0,
8.2 Interferences—Several types of interferences may affect
and 3.0 times the expected concentration of the analyte(s) in
measurements. This is especially true for test solutions con-
the test solution. The final analyte concentration in the test
taining high concentrations of solids or acids or containing
solution should be at or above the LOQ. The final analyte
elements having intense emission, a large number of atomic
concentration in the highest spike should not exceed the linear
emission lines, or high concentrations of easily ionized ele-
dynamicrangeoftheemissionlineused.Diluteallsolutionsto
ments (EIEs). The presence of interferences should be consid-
the mark and mix. Prepare an equal volume of the reagent
ered when selecting calibration solutions and the method of
blank solution if using 10.6.2. Multiply the final value by a
analysis. See 8.2.3 for suggestions on how to compensate for
factor to compensate for dilution.
interferences.
6.8 Calibration Verification Solution—To verify the
8.2.1 Types of Interference:
calibration, prepare one or more solutions whose concentra-
8.2.1.1 Chemical Interferences—Effects from excitation,
tionsarebetweenthehighestconcentrationcalibrationsolution
molecular compound formation, and solvent vaporization.
and the LOQ.
8.2.1.2 Physical Interferences—Factors that change the rate
of sample delivery such as viscosity, surface tension, and
6.9 Spike Recovery Sample—Prepare a test solution as
reaction with parts of the sample delivery system.
directed in the method. Add a spike of the analyte(s) equal to
8.2.1.3 Spectral Interferences—Spectral line or molecular
at least 5 times each analyte’s LOQ.
bandoverlapfromthematrixorsolvents,backgroundresulting
6.10 Limit of Quantification (LOQ) Solution—Prepare a
from continuum radiation, or stray light.
solution containing amounts of analyte three times to six times
8.2.2 Diagnosis of Interferences—Use the following proce-
the method detection limit or 10 % to 20% of the BEC and
dures for each new sample matrix:
matched as closely to the matrix as possible.
8.2.2.1 Comparison with Alternative Method(s) of
Analysis—Use established methods to compare analytical re-
7. Hazards
sults where possible.
7.1 Protect eyes from the intense ultraviolet (UV) radiation
8.2.2.2 Wavelength Scanning—If possible, scan the wave-
of the plasma.
length region near the analyte emission to detect spectral
7.2 Follow the manufacturer’s recommended operating
interferencesandhighbackgroundincalibrationsolutions,test
practicesforinitiatingtheplasmaandoperatingtheinstrument. solutions, and solutions containing suspected interfering ele-
ments.
7.3 Ensure that HF-resistant materials are used when ana-
8.2.2.3 Spike Recovery—Add a known quantity or spike of
lyzing solutions containing HF. Avoid strongly caustic solu-
the analyte equal to at least five times the LOQ. It should be
tions that may cause the ceramic sleeves of the electrodes to
recovered to within 6 2 σ of 100%, where σ is the standard
fuse.
deviation of at least three replicate measurements. If not, a
7.4 For other safety precautions, refer to Practice E50.
matrix effect or other interference may be present.
8. Characterization of Analytical Lines
8.1 Overview:
nd
Harrison, G. R., MIT Wavelength Tables Vol. 1, 2 Edition, MITPress,August
8.1.1 When researching a new method, use the recommen-
1969.
Meggars,W.F.,Corliss,C.H.,andScribner,B.F., Table of Spectral Intensities:
dations in this section to select a wavelength and evaluate the
Part I—Arranged by Elements: Part II—Arranged by Wavelengths, NBS Mono-
possible interferences. Measure the approximate linear range,
graph No. 145, Government Printing Office, Washington, D. C. (1975).
BEC, sensitivity, LOQ experimentally, and ascertain that they 5
Phelps, F. M., MIT Wavelength Tables, Vol. II, Wavelenghts by Element, MIT
areadequatefortheanalysis.Oncethesehavebeenestablished
Press, November 1982.
Reader, J. and Corliss, C. H., NSRDS-NBS 68, Wavelengths and Transition
for a specific instrument, periodic confirmation is recom-
Probabilities for Atoms and Atomic Ions, Washington, D. C., 1980.
mended and especially whenever a change is made in the
Winge, R. K., Fassel, V. A., Peterson, V. J., and Floyd, M. A., Inductively
hardware (for example, transport or detection devices) or
Coupled Plasma-Atomic Emission Spectroscopy: An Atlas of Spectral Information,
optics. Confirm by analysis of controls, including LOQ mea- Elsevier Science Publishers, Amsterdam, 1985.
E1097 − 12 (2017)
8.2.2.4 Serial Dilution—If the analyte concentration is suf- than 10%, repeat the process using one of the lower concen-
ficiently high, analysis of a ten-fold dilution should agree with trations as the high calibration solution. The upper limit of the
the expected concentration to within 5%. If not, a chemical or linearrangeisestablishedwhenthelessconcentratedsolutions
physical interference may be present. deviate from the expected value by less than 10%.
8.2.2.5 Equivalent Analyte Concentration—To obtain a 8.3.2 Lower Limit—The lower end of the linear range is the
quantitative measurement of the amount of interference from
LOQ.
individualelements,measuretheequivalentanalyteconcentra-
8.3.3 The linear range can vary with the matrix.
tion by testing 1000-mg/L solutions of these elements without
8.4 Background Equivalent Concentration (BEC)—
using background correction.
Calibrate the DCP with a high concentration calibration solu-
8.2.3 Correction for Interference Effects—If interference
tion that is approximately 20 times the expected BEC and a
effects are indicated, use one or more of the following
blank. Block the entrance slit and measure while in the sample
techniques:
analysis mode. Record the absolute value of the resulting
8.2.3.1 Alternative Wavelength—Select an analyte emission
negative concentration as the BEC.The BEC is approximately
line free from spectral interferences and having the required
equal to the intercept of a linear calibration curve.
sensitivity, linear range and DLs if one can be found.
8.5 Detection Limits (DL)—Follow the directions in the test
8.2.3.2 Background Correction—If the instrument is
method for determining and interpreting DL(s). If no instruc-
equipped for background correction, scan the samples and
tions are available, determine the DL(s) as follows:
calibration solutions. Select one or more background correc-
8.5.1 Instrument Detection Limit (IDL)—The IDL is used
tion positions in a level area of the background, preferably at a
forcharacterizingandcomparinganalyticallines.Calibratethe
low point. Refer to instrument operating manuals for specific
instrumentwithahighconcentrationsingle-elementcalibration
background correction procedures. Confirm with spikes and
solution and a blank. The calibration solution should be
controls that background correction is working properly.
between three and ten times the BEC. Set the instrument to
8.2.3.3 Standard Additions—Prepare the standard addition
take nine 10-s integrations and display the standard deviation.
test solutions by adding known increments of analyte(s) as
Measure the blank solution as a test solution three times.
directedin6.7.Testasdirectedin10.6.Inmostcases,thiswill
Calculate the instrument detection limit as follows:
compensateforchemicalandphysicalinterferences,butnotfor
spectral interferences.
2 2 2
IDL 53= σ 1σ 1σ /3 (1)
~ !
1 2 3
8.2.3.4 Dilution—If the analyte concentration is sufficiently
where σ , σ , and σ are the standard deviations obtained on
high, the analyte can be determined on a dilution. A ten-fold
1 2 3
the three replicate readings of the blank.
dilutionmayreducetheeffectofsomeinterferences,especially
matrix enhancement. Prepare different calibration solutions as
NOTE 2—The detection limit described by the instrument manufacturer
required. Dilution will not reduce spectral interferences if the
was calculated as three times the average of the three standard deviations.
analyte and interfering wavelength are close or coincident.
Poolingthestandarddeviationsyieldsslightlyhigherdetectionlimitsthan
those calculated by averaging.
8.2.3.5 Matrix-Matching—Match the matrix of the calibra-
tion solutions to that of the test solution as closely as possible.
8.5.2 Method Detection Limit (MDL)—The detection limit
Ascertainthatthematrixisfreeoftheanalyte.Ifthematrixhas
for an analyte in a given matrix is often different from what is
awell-defined,smallamountofanalyte,addthistotheamount
reported in the literature. For an indication of the effect of the
measured by the instrument when the results are calculated or
matrix, compare the MDL with the IDL. Follow the instruc-
addittothenominalconcentrationofthecalibrationsolutions.
tions of 8.5.1, taking the measurements on the matrix blank.
8.2.3.6 Calculated Compensation—Use equivalent analyte
Calculate the MDL as follows:
concentrations to correct for known amounts of interfering
2 2 2
MDL 53= σ 1σ 1σ /3 (2)
~ !
1 2 3
elements.
8.2.3.7 Buffers—Additions of lithium, sodium, potassium,
where σ , σ , and σ are the standa
...