ASTM E1097-97

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1097 – 97
Standard Guide for
Direct Current Plasma Emission Spectrometry Analysis
This standard is issued under the fixed designation E 1097; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 882 Guide for Accountability and Quality Control in the
Chemical Analysis Laboratory
1.1 This guide covers procedures for using a direct current
E 1601 Practice for Conducting an Interlaboratory Study to
argon plasma atomic emission spectrometer to determine the
Evaluate the Performance of an Analytical Method
concentration of elements in solution. Recommendations are
E 1832 Practice for Describing and Specifying a Direct-
provided for preparing and calibrating the instrument, assess-
Current Plasma Optical Emission Spectrometer
ing instrument performance, diagnosing and correcting for
interferences, measuring test solutions, and calculating results.
3. Terminology
A method to correct for instrument drift is included.
3.1 Definitions:
1.2 This guide does not specify all the operating conditions
3.1.1 For definitions of terms used in this guide, refer to
for a direct current plasma because of the differences between
Terminology E 135.
models of these instruments. Analysts should follow instruc-
3.2 Definitions of Terms Specific to This Standard:
tions provided by the manufacturer of the particular instru-
3.2.1 background equivalent concentration (BEC), n—the
ment.
analyte concentration whose signal is equivalent to the signal
1.3 This guide does not attempt to specify in detail all of the
generated by the plasma and matrix at the analyte line when the
hardware components and computer software of the instru-
actual analyte concentration is zero.
ment. It is assumed that the instrument, whether commercially
3.2.2 detection limit (DL), n—the lowest detectable quantity
available, modified, or custom built, will be capable of per-
equal to three times the standard deviation of a blank. Types of
forming the analyses for which it is intended, and that the
detection limits are as follows:
analyst has verified this before performing the analysis.
3.2.2.1 approximate detection limit (ADL), n—three percent
1.4 This standard does not purport to address all of the
of the background equivalent concentration for an analytical
safety concerns, if any, associated with its use. It is the
line not background corrected. The ADL is a useful check on
responsibility of the user of this standard to establish appro-
daily performance.
priate safety and health practices and determine the applica-
3.2.2.1.1 Discussion—The IDL and MDL are useful in
bility of regulatory limitations prior to use. Specific precau-
establishing the low end of the linear range and as a guide in
tionary statements are given in Section 8.
the preparation of calibration and check solutions.
2. Referenced Documents 3.2.2.2 instrumental detection limit (IDL), n—For d-c
plasma, the analyte concentration corresponding to three times
2.1 ASTM Standards:
the standard deviation of the background noise beneath the
E 29 Practice for Using Significant Digits in Test Data to
2 analyte line on a set of nine consecutive 10-s measurements of
Determine Conformance with Specifications
the background intensity of the blank. The IDL is useful in
E 50 Practices for Apparatus, Reagents, and Safety Precau-
3 characterizing and comparing analytical lines.
tions for Chemical Analysis of Metals
3.2.2.3 method detection limit (MDL), n—the detection
E 135 Terminology Relating to Analytical Chemistry for
3 limit measured on the matrix blank. The MDL indicates the
Metals, Ores, and Related Materials
effect of the matrix.
E 743 Guide for Spectrochemical Laboratory Quality As-
4 3.2.3 equivalent analyte concentration, n—the apparent
surance
concentration of an interfering element on an analyte, deter-
E 876 Practice for Use of Statistics in the Evaluation of
4 mined by measuring a 1000-mg/L solution of the interfering
Spectrometric Data
element at the analyte wavelength.
3.2.4 interference, n—any chemical, physical, or spectral
This guide is under the jurisdiction of ASTM Committee E-1 on Analytical
effect that changes the apparent net emission intensity from a
Chemistry for Metals, Ores, and Related Materials and is the direct responsibility of
spectral line other than a change in concentration of the
Subcommittee E01.20 on General Analytical Practices.
Current edition approved Oct. 10, 1997. Published June 1998. Originally
element emitting that spectral line.
published as E-3 Proposal P152. Last previous edition E 1097 – 93.
3.2.5 linear dynamic range, n—the concentration range
Annual Book of ASTM Standards, Vol 14.02.
from the quantifiable limit to the highest concentration that
Annual Book of ASTM Standards, Vol 03.05.
Annual Book of ASTM Standards, Vol 03.06.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1097
remains within 6 10 % of linearity based on lower concentra- 6. Preparation of Solutions
tions.
6.1 Solutions are prepared for different purposes. Not all
3.2.6 order, spectral, n—the number of wavelength differ-
may be necessary for every test. Prepare only those directed by
ences between reflections from successive grooves of a grating
the method or required to meet specific experimental objec-
or echelle; typically one or two wavelengths for the first or
tives.
second orders of a grating, 50 or 51 wavelengths for the fiftieth
6.2 Rinse Solution—Prepare a rinse solution to contain the
and fifty-first orders from an echelle.
acids or bases present in the test solution at the same
3.2.6.1 Discussion—In the DCP echelle, a number of wave-
concentration. Prepare a quantity sufficient to clean the end of
lengths appear in two adjacent orders, and these wavelengths
the sample uptake tubing and to flush the sample introduction
usually have similar intensities.
system between each determination of calibration solutions and
3.2.7 quantifiable limit (QL)—the lowest concentration at
test solutions. Occasionally, an analyte requires a conditioning
which the instrument can measure reliably with a defined error
time in the aspiration/nebulization system of the instrument. In
and confidence level.
this case, use the test solution as a rinse and allow a sufficient
3.2.8 sensitivity—the slope of the analytical curve, which is
residence time before taking a reading.
the ratio of the change in emission intensity to the change in
6.3 Reagent Blank Solution—This solution consists of all
concentration.
reagents and other additions at the same concentration used in
preparing the test solution. Carry this solution through the
4. Summary of Guide
entire sample preparation procedure.
4.1 Direct current argon plasma atomic emission spectrom-
6.4 Matrix Blank Solution—Prepare this solution to be as
eters, either simultaneous or sequential, measure elements in
close in composition to the test solution as possible (including
solution using atomic emission. Samples and calibration solu-
dissolution reagents and matrix elements), but omitting the
tions are nebulized and the aerosol is transported to the direct
elements to be determined. The matrix elements should be of
current plasma jet where excitation occurs and characteristic
high purity.
emission spectra are produced. The spectra are dispersed by an
6.5 Control—Select standard reference material, certified
echelle grating and cross-dispersed by a prism or grating. They
reference material, or other material of known composition and
impinge on photomultiplier tubes, whose outputs are inter-
prepare a solution of it according to the appropriate test
preted by a computer as emission intensities. Background
method. This solution may be used to verify the initial
correction can be used to compensate for some interferences.
calibration. Analyze the control regularly as a blind sample and
The computer generates calibration curves and calculates
use the results for quality control as directed in Guide E 882.
analyte concentration.
6.6 Calibration Solutions—The number and type of these
5. Significance and Use
solutions will depend on the method, and on the type of plasma
5.1 Accurate application of direct current plasma spectrom- instrument and its microprocessor. Generally, prepare two
etry requires proper preparation of test solutions, accurate instrument calibration solutions, one high concentration, and
calibration, and control of analytical procedure, that are treated one low concentration or a blank, that bracket the expected
broadly in this guide, ASTM test methods that refer to this concentration range of the sample test solutions. Also prepare
guide shall provide specifics on solutions, calibration, and at least one other intermediate calibration solution. More may
procedures. be prepared if the microprocessor can utilize them, especially
5.2 Application of direct current plasma analysis is prima- if the test solutions are expected to have a large range of
rily concerned with testing materials for compliance with analyte composition of if the calibration curve is non-linear.
specifications, but may range from qualitative estimations to Prepare them by adding aliquots from stock solutions to
umpire analysis. These may involve measuring major and solutions that are similar in composition to the test sample.
minor constituents or trace impurities, or both. This guide
6.6.1 Match the matrix of the calibration solutions as
suggests some approaches to these different analytical needs.
closely as possible to that of the test solution in acidity, total
5.3 This guide assists analysts in developing new methods.
solids, reagents, and matrix elements, especially if easily
5.4 It is assumed that the users of this guide be trained
ionized elements are present. Some matrix elements may be
analysts capable of performing common laboratory procedures eliminated if it can be shown by spike addition or standard
skillfully and safely. It is expected that the work will be
additions that the effect on the test solution analytes is
performed in a properly equipped laboratory.
insignificant. Use stock solutions or pure elements prepared by
5.5 This guide does not purport to define all of the quality
a method similar to that used to prepare the test solutions. If the
assurance parameters necessary for d-c plasma analysis. Ana-
composition of the test solution is unknown to the extent that
lysts should ensure that proper quality assurance procedures
matched matrix solutions cannot be prepared, or if a suffi-
are followed, especially those defined by the test method. Refer
ciently pure matrix material is not available, refer to the
to Guides E 743 and E 882 or the USEPA Contract Laboratory
method of standard additions described in 6.7 and 10.6.
Program.
NOTE 1—If the instrument is designed to use a blank as the low
concentration calibration solution, prepare it the same way as the high
concentration calibration solution is prepared, omitting the elements to be
USEPA Contract Laboratory Program Statement of Work for Inorganic
determined. Where matched matrix calibration solutions are employed,
Analysis, Multi-Media, Multi-Concentration, SOW 7/88, Sample Management
Office, P.O. Box 818, Alexandria, VA 22313, 1988. this will be the matrix blank solution.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1097
6.6.2 Optimum Calibration Solution Concentration instrument, periodic confirmation is recommended and espe-
Range—For calibration in the linear range, the highest con- cially whenever a change is made in the hardware (for
centration should be no more than 85 % of the upper limit of example, transport or detection devices) or optics. Confirm by
the calibration curve linearity. For an instrument that accepts a means of controls or quantifiable limit measurements, or both,
low concentration calibration solution, it’s concentration that the daily performance of the instrument meets the criteria
should be at least four times the method detection limit and of the method.
above the quantifiable limit. 8.1.2 When using an established method for the first time,
6.7 Standard Additions Solutions—Prepare as directed in confirm that freedom from interferences, linearity, detection
either 6.7.1 or 6.7.2 as follows: limit, and sensitivity meet the criteria of the method.
6.7.1 Prepare four separate test solutions of the sample. To 8.1.3 For information on wavelengths, refer to Bosshart,
7 8
all but one, add known amounts of the analyte equal to 0.5, 1.0, Harrison, or Winge .
and 1.5 or 1.0, 2.0, and 3.0 times the expected concentration of 8.2 Interferences—Several types of interferences may affect
the analyte(s) in the test solution. The original analyte concen- measurements. This is especially true for test solutions con-
tration must be at or above it’s quantifiable limit. The final taining high concentrations of solids or acids or containing
analyte concentration in the highest spike must not be greater elements having intense emission, a large number of emission
than the linear range of the emission line used. Dilute all lines, or high concentrations of easily ionized elements. The
solutions to the mark and mix. Prepare an equal volume of the presence of interferences should be considered when selecting
reagent blank solution when using 10.6.2. calibration solutions and the method of analysis. See 8.2.3 for
6.7.2 Transfer four equal volumes of a test solution to four suggestions on how to compensate for interferences.
volumetric flasks of the same size. To all but one, add known 8.2.1 Types of Interference:
amounts of the analyte equal to 0.5, 1.0, and 1.5 or 1.0, 2.0, and 8.2.1.1 Chemical Interferences—Effects from excitation,
3.0 times the expected concentration of the analyte(s) in the molecular compound formation, and solvent vaporization.
test solution. The final analyte concentration in the test solution 8.2.1.2 Physical Interferences—Factors that change the rate
should be at or above the quantifiable limit. The final analyte of sample delivery such as viscosity, surface tension, and
concentration in the highest spike should not exceed the linear reaction with parts of the sample delivery system.
dynamic range of the emission line use
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