ASTM E2054-99

Practice for Performance-Based Description of Instruments in Chemical Analysis Methods (Withdrawn 2005)

SCOPE
1.1 This practice covers procedures for specifying instruments for chemical analysis by performance rather than by design.
1.2 The provisions of this practice do not apply to classical chemical method of analysis.
WITHDRAWN RATIONALE
This practice covers procedures for specifying instruments for chemical analysis by performance rather than by design.
Formerly under the jurisdiction of Committee E01 on Analytical Chemistry of Metals, Ores, and Related Materials, this practice was withdrawn in May 2005. This standard is being withdrawn without replacement because this practice has been superseded by the new Practice E 2410 and conflicts with some of the principles adopted in the new standard.

General Information

• Status: Withdrawn
• Publication Date: 09-Dec-1999
• Withdrawal Date: 22-May-2005
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: E01 - Analytical Chemistry for Metals, Ores, and Related Materials
• Drafting Committee: E01.22 - Laboratory Quality

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E2054–99
Practice for
Performance–Based Description of Instruments in Chemical
Analysis Methods
This standard is issued under the fixed designation E 2054; 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 3.2.3 minimum instrument sensitivity index, MISI, n—a
figure of merit used to compare sensitivity of instruments at
1.1 This practice covers procedures for specifying instru-
low analyte levels.
ments for chemical analysis by performance rather than by
3.2.4 relative instrument sensitivity index, RISI, n—a figure
design.
of merit used to compare sensitivity of instruments at elevated
1.2 The provisions of this practice do not apply to classical
analyte levels.
chemical method of analysis.
4. Summary of Practice
2. Referenced Documents
4.1 Theauthororataskgroupconductinganinterlaboratory
2.1 ASTM Standards:
study (ILS) examines a measuring instrument to determine
E 135 Terminology Relating to Analytical Chemistry for
which components and operations contribute to imprecision of
Metals, Ores, and Related Materials
results. The task group collects ILS data and calculates values
E 396 Test Method for Chemical Analysis of Cadmium
for criteria that define acceptable operation of those compo-
E 1024 Guide for Chemical Analysis of Metals and Metal
nents. Instrument tests and critical values are written into the
Bearing Ores by Flame Atomic Absorption Spectropho-
Apparatus section. Before applying a method, users verify that
tometry
an instrument meets the specified performance criteria.
E 1601 Practice for Conducting an Interlaboratory Study to
Evaluate the Performance of an Analytical Method
5. Significance and Use
E 1763 Guide for Interpretation and Use of Results from
5.1 Instrumental methods specify measurement apparatus
Interlaboratory Testing of Chemical Analysis Methods
by name and a brief design description. An instrument de-
E 1914 Practice for the Use of Terms Relating to the
signed differently than described may provide equivalent
Development and Evaluation of Methods of Chemical
measurements. Relying solely on design specifications some-
Analysis
times excludes instruments capable of the required perfor-
E 2055 Practice for Referencing Methods for Chemical
mance.
Analysis of Metals and Related Materials
5.2 This practice requires each method to specify tests and
3. Terminology criteria to measure critical performance characteristics of an
instrument. The tests provide verification that a user’s instru-
3.1 Definitions—For definitions and use of terms used in
ment is capable of producing results that reflect the precision
this practice, refer to Terminology E 135 and Practice E 1914.
stated in the method.
3.2 Definitions of Terms Specific to This Standard:
5.3 Any instrument designed to measure the physical prop-
3.2.1 classical analytical method, n—a method based upon
erties in the specified analytical systems may be used in a
classical analytical measurements, that is, weight (as by
method if it meets the performance criteria. If an instrument’s
analytical balance), volume (as by buret), or both.
performance does not meet the criteria, a user may still apply
3.2.2 instrumental analytical method, n—a method based
the method, but is warned that results may have greater
upon analytical measurements other than those employed in
variability than is specified in the method. (Warning—
classical methods.
Meeting instrument performance criteria does not guarantee
expected precision and accuracy. The tests warn only of
This practice is under the jurisdiction of ASTM Committee E-1 on Analytical
excessive instrumental error. A user shall employ reference
Chemistry for Metals, Ores, and Related Materials and is the direct responsibility of
materials in accordance with Practice E 2055 and adhere
Subcommittee E01.22 on Statistics and Quality Control.
strictly to all requirements of a method to obtain results in
Current edition approved Dec. 10, 1999. Published February 2000.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
accordance with its Precision and Bias section.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.4 Classical analytical methods are not covered by this
Standards volume information, refer to the standard’s Document Summary page on
practice.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2054–99
6. Minimum Performance Parameters 7.2 Instrument Test Criteria—The task group uses the ILS
test data to calculate critical values for the acceptance statistics
6.1 In instrumental methods, results are calculated from an
established in 7.1.
instrument’s response to an analyte’s concentration. Readings
7.2.1 Instrument Sensitivity Indexes—Prepare a table of
arevisuallyestimatedvaluesfromaninstrument’sanalogscale
means, x¯, minimum method standard deviations, s , and other
M
ordigitalvaluesderivedmechanicallyorelectronicallyfromits
statistics as shown for the example in Table 1 in which each
output. A method specifies manual calculation of results from
laboratory provided 3 results. Calculate relative values for s :
M
instrument readings or programmed calculation by a computer.
Some instruments may be calibrated to provide readings
s 5 s /x (2)
rel M
directly in analyte content or concentration. In any case, a
Calculate the degrees of freedom:
method specifies one instrument sensitivity index near the
f 5 p 3 ~n–1! (3)
bottom and another near the top of an analyte’s calibrated
range. The associated performance tests, conditions, and crite-
where:
ria constitute minimum performance requirements for an
p = the number of laboratories contributing data, and
instrument.
n = the number of replicates from each laboratory.
From Annex A1, select a procedure for determining the
7. Instrument Tests
low–analyte sensitivity constant, k , high–analyte constant,
7.1 Instrument Test Protocols—Instrument performance
k , and their associated degrees of freedom, f and f .
rel 0 rel
tests are devised by the author or a task group before ILS
Determine the corresponding factors, F and F from Table 2.
0 rel
testing is begun. The statistical criteria for the tests are
Calculate critical index values for MISI and RISI:
calculated from the normal ILS statistics or from data collected
I 5 k 3 F (4)
=
0 0 0
separately as part of the ILS experiment.
7.1.1 Sensitivity Tests—All methods require sensitivity tests
attwoanalytelevels,onenearthelowend(MISI)andtheother
I 5 k 3 F (5)
=
rel rel rel
nearthehighend(RISI)ofacalibrationrange.Identifythetwo
Enter the critical values in the method’s test protocol.
test solutions or specimens in sufficient detail that users
7.2.2 Example for Copper in Iron Ore by FAA—The ILS
perform the tests on appropriate samples. For flame atomic
statistics for this method are shown in Table 1. By inspection,
absorption (FAA) methods, for example, specify the zero and
k = 0.0003 with f =70(F = 2.0) and k = 0.0150 with f =
0 0 0 rel rel
highest calibration solutions for determination of MISI and
160 (F = 1.9). From Eq 4, I = 0.00042; from Eq 5, I =
rel 0 rel
RISI, respectively. Provide instructions for the performance
0.021.Thesensitivitytestmightread:Preparetheinstrumentto
tests in the Apparatus section of the method. Sensitivity tests
measure copper in accordance with the manufacturer’s recom-
under this practice require 10 sequential readings on each test
mendations, and calibrate according to Section __. Record 10
material. For FAA methods, for example, the sensitivity test
sequential copper results for the zero calibration solution and
might read: “Prepare the instrument for measurements on the
10 for the highest calibration solution and calculate their
analyte in accordance with manufacturer’s recommendations,
sample standard deviations s and s , respectively. Calculate
0 H
and calibrate according to Section ___. Take 10 sequential
the relative standard deviation, s :
rel
readings on the zero calibration solution and 10 on the highest
s 5 s /x (6)
rel H H
calibration solution, and calculate the sample standard devia-
tions s and s , respectively. Calculate the relative standard
where x¯ is the mean for the highest calibration solution. If
0 H H
deviation: s is less than 0.00042 % copper, the instrument has satisfac-
tory low-level sensitivity. If s is less than 2.1 %, the instru-
rel
s 5 s /x (1)
rel H H
ment has satisfactory high-level sensitivity. If either statistic
where x¯ is the mean of the 10 high material readings. If s
H 0
frequently exceeds its index value, the instrument may con-
is less than [insert value of I ], the instrument has satisfactory
tribute to excessive variability in the corresponding calibration
low–level sensitivity. If s is less than [insert value of I ], the
rel rel
region.
instrument has satisfactory high–level sensitivity. If either
statistic frequently exceeds its index value, the instrument may TABLE 1 Sensitivity Statistics for Copper in Iron Ore
contribute excessive variability in the corresponding calibra-
Material Mean, x¯s s pf
M rel
tion region.”
1 0.001 0.0003 0.30 35 70
7.1.2 Special Tests—Add tests of other instrument param- 2 0.011 0.0007 0.064 39 78
3 0.072 0.0013 0.0181 39 78
eters, if appropriate (see Annex A2). For FAA, for example,
4 0.380 0.0059 0.0155 40 80
begin instrument testing with a response linearity test in
5 0.787 0.0115 0.0146 40 80
accordance with A2.3.
E2054–99
TABLE 2 F Factor
f Range F
11 2.9
12 2.8
13–14 2.7
15 2.6
16–18 2.5
19–21 2.4
22–27 2.3
28–36 2.2
37–58 2.1
59–120 2.0
> 120 1.9
ANNEXES
(Mandatory Information)
A1. SENSITIVITY CONSTANTS k AND k
0 rel
A1.1 Precision Models—Refer to Guide E 1763 for a gen- A1.3 Case 1 Example—The plot of s against copper
M
eral discussion of models for the precision of methods of content in Fig.A1.1 suggests that, in the ILS of the method for
chemicalanalysis.GuideE 1763dealsexclusivelywithrepeat- copper in iron ore by FAA (data from Table 1 in the practice),
ability and reproducibility, but the same principles apply to
only the lowest test material estimates a constant value for s .
M
relationships between analyte concentrations and minimum Thus the estimate of k is 0.0003 with f = 70. In Table 1,
0 0
methodstandarddeviations, s .Oneoftheproceduresoutlined
materials 4 and 5 exhibit nearly a constant value for s .
M
rel
in this annex provides a means to estimate the low–level
ApplyingEqA1.1andA1.2yieldspooledvaluesof k =0.015
rel
sensitivity constant, k , and the high–level constant, k .
and f = 160. These values of k , f , k , and f appear in the
0 rel
rel 0 0 rel rel
calculations of sensitivity indexes in 7.2.1.
A1.2 Case 1: Limited Test Materials—If the ILS is con-
ducted with a limited number of test materials, or if the analyte
A1.4 Case 2: Many Test Materials—If the ILS is conducted
content of one or more materials is nearly zero, set k equal to
with materials at many different analyte concentrations,
s ofthetestmaterialwithlowestanalytecontentorthepooled
M
C .C , the precision model may be applied. From the m data
1 m
value of n low materials with about the same s . Calculate f
M 0
pairs (s ,C) obtained in the ILS, calculate constants k and k
M 0 rel
for the low material for s . Degrees of freedom for an
M
in accordance with procedures in Annex A2 of E 1763. The
individual material, i,is f =p 3 (n – 1), where p laboratories
i
curve-fit process must be performed with a general non-linear
contribute n replicate results for the material. For data pooled
procedure or special least-squares algorithms to accommodate
over q low materials 1, 2, ., q, the equations for pooled k and
the model:
pooled f become:
2 2
2 2 2
s 5 k 1 ~C 3 k ! (A1.5)
=
~f !~s ! 1 ~f !~s ! 1 ··· 1 ~f !~s ! M 0 rel
1 M 1 2 M 2 q M q
k 5 (A1.1)
f 1 f 1 ··· 1 f
1 2 q
A1.5 Case 2 Example—TableA1.1 shows sensitivity statis-
f 5 f 1 f ··· 1 f (A1.2)
0 1 2 q
tics from an ILS employing 12 materials. The trends in s and
M
Set k equal to s of the test highest material or to the
rel rel
s are typical of data from methods that follow the general
rel
pooled value of m high materials having nearly the same s .
rel
precision model for instrument sensitivity. The data was fit to
For pooled high analyte materials 1, 2, ., m, the equations for
EqA1.5 using a standard non-linear technique. The sensitivity
pooled k and pooled f become:
rel rel
curve defined by the fitting constants k = 0.0002 and k =
0 rel
2 2 2
~f ! ~s ! 1 ~f ! ~s ! 1 ··· 1 ~f ! ~s !
0.0094 is shown on the plot of the data points in Fig.A1.2.The
rel 1 rel 1 rel 2 rel 2 rel m rel m
k 5 (A1.3)
rel
f 1 f 1 ··· 1 f
~ ! ~ ! ~ ! degrees of freedom for the sensitivity constants are 2 less than
rel 1 rel 2 rel m
the sum of the individual values in the f column, 560 for this
f 5 ~f ! 1 ~f ! 1 ··· 1 ~f ! (A1.4) example.
rel rel 1 rel 2 rel m
E2054–99
FIG. A1.1 Copper in Iron Ore by FAA
TABLE A1.1 Sensitivity Statistics for Copper in Iron and Steel by ICPS
Material Copper, % (C) s s nf
M rel
1 0.00144 0.0001642 0.1138 23 46
2 0.00152 0.0001542 0.1011 23 46
3 0.00523 0.0002585 0.0494 23 46
4 0.01269 0.0001833 0.0144 24 48
5 0.01435 0.0002938 0.0205 19 38
6 0.02223 0.0003037 0.0137 24 48
7 0.02548 0.0003462 0.0136 25 50
8 0.04276 0.0006389 0.0149 25 50
9 0.06356 0.0008146 0.0128 20 40
10 0.1719 0.001844 0.0107 25 50
11 0.2166 0.002556 0.0118 25 50
12 0.2819 0.002104 0.0075 25 50
E2054–99
FIG. A1.2 Copper in Iron and Steel by ICP
A2. SPECIAL TESTS
A2.1 Critical Parameters—Simple instruments require no practice does not address these methods because factors
calibration for ordinary use. A marked meter scale or titration affecting their precision and accuracy are discussed in detail
buretareexamples.Mostmodernanalyticalinstruments,onthe elsewhere.
other hand, measure complex physical properties.They require A2.2.2 Molecular Absorption Spectrometry—This tech-
preliminary adjustments, calibrations, and periodic checks and nique depends upon measurements of light absorption by
readjustments to compensate for changing instrumental and colored analyte species in solutions. Instrument response is
environmental conditions if their inherent accuracy and preci- strictly linear only over a restricted analyte concentration
sion are to be realized in normal use. The author of a method, range. Methods typica
...