Standard Guide for Optimizing, Controlling and Reporting Test Method Uncertainties from Multiple Workstations in the Same Laboratory Organization

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1.1 This guide describes a protocol for optimizing, controlling, and reporting test method uncertainties from multiple workstations in the same laboratory organization. It does not apply when different test methods, dissimilar instruments, or different parts of the same laboratory organization function independently to validate or verify the accuracy of a specific analytical measurement.
1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.

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ASTM E2093-00 - Standard Guide for Optimizing, Controlling and Reporting Test Method Uncertainties from Multiple Workstations in the Same Laboratory Organization
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Designation:E2093–00
Standard Guide for
Optimizing, Controlling and Reporting Test Method
Uncertainties from Multiple Workstations in the Same
Laboratory Organization
This standard is issued under the fixed designation E 2093; 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 Calibration and Testing Laboratories
ISO 9000 Quality Management and Quality System Ele-
1.1 This guide describes a protocol for optimizing, control-
ments
ling, and reporting test method uncertainties from multiple
workstations in the same laboratory organization. It does not
3. Terminology
apply when different test methods, dissimilar instruments, or
3.1 Definitions—For definitions of terms used in this guide,
different parts of the same laboratory organization function
refer to Terminology E 135.
independently to validate or verify the accuracy of a specific
3.2 Definitions of Terms Specific to This Standard:
analytical measurement.
3.2.1 data quality objectives, n—a model used by the
1.2 This standard does not purport to address all of the
laboratory organization to specify the maximum error associ-
safety concerns, if any, associated with its use. It is the
ated with a report value, at a specified confidence level.
responsibility of the user of this standard to establish appro-
3.2.2 laboratory organization, n—a business entity that
priate safety and health practices and determine the applica-
provides similar types of measurements from more than one
bility of regulatory limitations prior to use.
workstation located in one or more laboratories, all of which
2. Referenced Documents operate under a unified quality system.
3.2.3 maximum deviation, n—the maximum error associ-
2.1 ASTM Standards:
ated with a report value, at a specified confidence level, for a
E 135 Terminology Relating to Analytical Chemistry for
given concentration of a given element, determined by a
Metals, Ores, and Related Materials
specific method, throughout a laboratory organization.
E 350 Test Methods for ChemicalAnalysis of Carbon Steel,
3.2.4 workstation, n—a combination of people and equip-
Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and
ment that executes a specific test method using a single
Wrought Iron
specifiedmeasuringdevicetoquantifyoneormoreparameters,
E 415 Test Method for Optical Emission Vacuum Spectro-
with each report value having an established estimated uncer-
metric Analysis of Carbon and Low-Alloy Steel
tainty that complies with the data quality objectives of the
E 1329 Practice for Verification and the Use of Control
laboratory organization.
Charts in Spectrochemical Analysis
E 1601 Practice for Conducting an Interlaboratory Study to
4. Significance and Use
Evaluate the Performance of an Analytical Method
4.1 Many competent analytical laboratories comply with
E 2027 Practice for Conducting Proficiency Tests in the
accepted quality system requirements such as ISO 9000,
Chemical Analysis of Metals, Ores, and Related Materials
QS9000, and ISO 17025. When using standard test methods,
2.2 ISO Standards:
their test results on the same sample should agree with those
ISO 17025 General Requirements for the Competence of
from other similar laboratories within the reproducibility
estimates (R2) published in the standard. Reproducibility
estimates are generated as part of the interlaboratory studies
(ILS), of the type described in Practice E 1601, during the
This guide is under the jurisdiction of ASTM Committee E01 on Analytical
Chemistry for Metals, Ores and Related Materials and is the direct responsibility of
Subcommittee E01.22 on Statistics and Quality Control .
Current edition approved May 10, 2000. Published July 2000. Available from American National Standards Institute, 11 W. 42nd St., 13th
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Floor, New York, NY 10036.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Quality Systems Requirements, Chrysler Corporation, Ford Motor Company,
Standards volume information, refer to the standard’s Document Summary page on and General Motors Corporation—available from AIAG, 26200 Lahser Rd.,
the ASTM website. Southfield, MI 48034.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2093–00
standardization process. Competent laboratories participate in 5.2 Identify the workstations to be included in the protocol
proficiency tests, such as those carried out according to and harmonize their experimental procedures, calibrations, and
Practice E 2027, to confirm that that they perform consistently control strategies so that all performance data from all work-
over time. In both ILS and proficiency testing protocols, it is stations are directly statistically comparable.
generally assumed that only one work station is used to
5.3 Tabulate performance data for each workstation and
generate the data.
ensure that each workstation complies with the laboratory
4.2 Many laboratories have workloads, or logistical require-
organization’s data quality objectives.
ments, or both, that dictate the use of multiple work stations.
5.4 Document items covered in 5.1-5.3.
Some have multiple stations in the same area (central labora-
5.5 Establish and document a laboratory organization-wide
toryformat).Others’stationsarescatteredthroughoutafacility
proficiency test policy that provides traceability to all work-
(at-line laboratory format). Often, analysis reports do not
stations.
identify the workstation used for the testing, even if worksta-
5.6 Operate each workstation independently as described in
tions differ in their testing uncertainties. Problems can arise if
its associated documentation. If any changes are made to any
clientsmistakenlyattributevariationinreportvaluestoprocess
workstation or its performance levels, document the changes
rather then workstation variability. These problems can be
and ensure compliance with the laboratory organization’s data
minimized if the laboratory organization sets, complies with,
quality objectives.
and reports a unified set of data quality objectives throughout.
4.3 This guide describes a protocol for efficiently optimiz-
6. Procedure
ing and controlling variability in test results from different
workstations used to perform the same test. It harmonizes
6.1 Identify the test method and establish the data quality
calibration and control protocols, thereby providing the same
objectives to be met throughout the laboratory organization.
level of measurement traceability and control to all worksta-
6.1.1 Multi-element test methods can be handled concur-
tions. It streamlines documentation and training requirements,
rently, provided that all elements are measured using common
thereby facilitating flexibility in personnel assignments. Fi-
technology, and that the parameters that influence data quality
nally, it offers an opportunity to claim traceability of profi-
are tabulated and evaluated for each element individually. An
ciency test measurements to all included workstations, regard-
example is Test Method E 415 that covers the analysis of plain
less on which workstation the proficiency test sample was
carbon and low alloy steel by optical emission vacuum
tested. The potential benefits of utilizing this protocol increase
spectrometry. Workstations can be under manual or robotic
with the number of workstations included in the laboratory
control, as long as the estimated uncertainties are within the
organization.
specifieddataqualityobjectives.Avoidhandlingmulti-element
4.4 This guide can be used to identify and quantify benefits
test methods concurrently that use different measurement
derived from corrective actions relating to under-performing
technologies. Their procedures and error evaluations are too
workstations. It also provides means to track improved perfor-
diverse to be incorporated into one easy-to-manage package.
mance after improvements have been made.
An example of test methods that should not be combined into
4.5 It is assumed that all who use this guide comply with
one program is Test Methods E 350 because those methods
ISO 17025, especially including the use of documented proce-
cover many different measurement technologies.
dures, the application of statistical control of measurement
6.1.2 Set the data quality objectives for the application of
processes, and participation in proficiency testing.
the method throughout the laboratory organization, using
4.6 The general principles of this protocol can be adapted to
customer requirements and available performance data. At the
other types of measurements, such as mechanical testing and
conclusion of this effort, the laboratory organization will know
on-lineprocesscontrolmeasurements,suchastemperatureand
the maximum deviation allowed in any report value, at any
thickness gaging. In these areas, users may need to establish
concentrationlevel,usingthemethodofchoice.Anexampleof
their own models for defining data quality objectives and
a possible method for establishing data quality objectives is
proficiency testing may not be available or applicable.
given in Annex A1.
4.7 It is especially important that users of this guide take
6.2 Identify the workstations to be included in the protocol
responsibility for ensuring the accuracy of the measurements
and harmonize their experimental procedures, calibrations, and
madebytheworkstationstobeoperatedunderthisprotocol.In
control strategies so that all performance data from all work-
addition to the checks mentioned in 6.2.3, laboratories are
stations are directly statistically comparable.
encouraged to use other techniques, including, but not limited
6.2.1 Foreachworkstation,listthepersonnelandequipment
to, analyzing some materials by independent methods, either
that significantly influence data quality. Each component of
within the same laboratory or in collaboration with other
each workstation does not have to be identical, such as from
equally competent laboratories. The risks associated with
the same manufacturer or model number; however, each
generating large volumes of data from carefully synchronized,
workstation must perform the functions described in the test
but incorrectly calibrated multiple workstations are obvious
method.
and must be avoided.
6.2.2 Harmonize the experimental procedures associated
5. Summary
with each workstation to ensure that all stations are capable of
5.1 Identify the test method and establish the data quality generating statistically comparable data that can be expected to
objectives to be met throughout the laboratory organization. fall within the maximum allowable limits for the laboratory
E2093–00
organization. Ideally, all workstations within the laboratory
TABLE 1 Continued
organization will have essentially the same experimental pro-
Assumed
cedures.
ERM True Conc. WS Av. UCL LCL Std. Dev.
6.2.3 Harmonize calibration protocols so that the same
2 0.02475 0.02940 0.02010 0.00155
calibrants are used to cover the same calibration ranges for the 3 0.02467 0.02884 0.02050 0.00139
same elements on all instruments. Avoid the use of different
Si 638 0.01688 1 0.01565 0.01718 0.01412 0.00051
calibrants on different instruments that may lead to calibration
2 0.01755 0.01863 0.01647 0.00036
3 0.01743 0.01830 0.01656 0.00029
biases and uncertainties that are larger than necessary. Make
sure that all interferences and matrix effects are addressed.
648 0.23283 1 0.22900 0.23911 0.21889 0.00337
Verify the calibrations with certified reference materials not
2 0.23240 0.24404 0.22076 0.00388
3 0.23710 0.24619 0.22801 0.00303
used in the calibration, when possible. Record the findings for
each workstation.
Cu 638 0.26588 1 0.26685 0.27555 0.25815 0.00290
6.2.4 Use the same SPC materials and data collection
2 0.26569 0.27295 0.25843 0.00242
3 0.26511 0.27276 0.25746 0.00255
practices on all work stations (see Note 1). Carry SPC
materials through all procedural steps that contribute to the
648 0.10700 1 0.10654 0.11089 0.10219 0.00145
measurement uncertainty. Develop control charts in accor-
2 0.10753 0.11086 0.10420 0.00111
3 0.10694 0.13784 0.07604 0.01030
dance with E 1329, or equivalent practice.
NOTE 1—Generally, it is recommended that SPC concentrations be set Ni 638 0.69005 1 0.70014 0.72516 0.67512 0.00834
1 1
2 0.68252 0.69440 0.67064 0.00396
about ⁄3 from the top and ⁄3 from the bottom of each calibration range. It
3 0.68750 0.71309 0.66191 0.00853
isalsorecommendedthatsinglepoint,movingrangechartsbeusedsothat
calculatedstandarddeviationsreflectthenormalvariationinreportvalues.
648 0.25063 1 0.25174 0.25906 0.24442 0.00244
2 0.24891 0.25350 0.24432 0.00153
6.2.5 Collect at least 20 SPC data points from each work
3 0.25123 0.25927 0.24319 0.00268
station to ensure that the workstations are under control and
Cr 638 0.03746 1 0.03760 0.03886 0.03634 0.00042
that the control limits are representative.
2 0.03745 0.03832 0.03658 0.00029
6.3 Tabulate performance data for each workstation and
3 0.03732 0.03813 0.03651 0.00027
ensure that each workstation complies with the laboratory
648 0.23728 1 0.23190 0.23637 0.22743 0.00149
organization’s data quality objectives.
2 0.24012 0.24414 0.23610 0.00134
6.3.1 Tabulate the SPC data by parameter (element), Refer-
3 0.23982 0.24300 0.23664 0.00106
ence material, assumed true concentration, workstation, aver-
Sn 638 0.00278 1 0.00255 0.00507 0.00003 0.00084
age, upper control limit, lower control limit, and standard
2 0.00257 0.00296 0.00218 0.00013
deviation, as illustrated in Table 1 (see Notes 2 and 3).
3 0.00322 0.00490 0.00154 0.00056
648 0.01424 1 0.01402 0.01600 0.01204 0.00066
TABLE 1 Sample SPC Control Parameter Tabulation
2 0.01412 0.01502 0.01322 0.00030
3 0.01458 0.01668 0.01248 0.00070
Assumed
ERM True Conc. WS Av. UCL LCL Std. Dev.
Mo 638 0.06346 1 0.06253 0.06604 0.05902 0.00117
C 638 0.06014 1 0.05996 0.06764 0.05228 0.00256 2 0.06398 0.06533 0.06263 0.00045
2 0.06040 0.06364 0.05716 0.00108 3 0.06387 0.06621 0.06153 0.00078
3 0.06005 0.06308 0.05702 0.00101
648 0.08652 1 0.08539 0.08995 0.08083 0.00152
648 0.25665 1 0.25212 0.27069 0.23355 0.00619 2 0.08722 0.08941 0.08503 0.00073
2 0.25923 0.27402 0.24444 0.00493 3 0.08696 0.09011 0.08381 0.00105
3 0.25861 0.27283 0.24439 0.00474
V 638 0.02107 1 0.02076 0.02184 0.01968 0.00036
Mn 638 0.29832 1 0.29620 0.30304 0.28936 0.00228 2 0.02114 0.02219 0.02009 0.00035
2 0.29967 0.30567 0.29367 0.00200 3 0.02132 0.02231 0.02033 0.00
...

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