United States
Environmental Protection
Environmental Monitoring and Sup
Cincinnati OH 45268
Research and Development
EPA/600/S4-85/056  Dec. 1985
Project  Summary
Choosing  Cost-Effective QA/QC
Programs for  Chemical Analysis
Lloyd P. Provost and Robert S. Elder
  The primary objective of the full report
is to provide guidance for choosing
cost-effective quality assurance/qual-
ity control (QA/QC) programsf or chem-
ical laboratories. It  describes general
principles of QA/QC, the specific tools
available, and the information needed
to choose appropriate tools for specific
needs. The report does not give detailed
discussions of how to apply each quality
control tool; references are given for
more detailed information.
  The major tasks of this project were:

 • a literature search to identify current
   QA/QC practices for inorganic and
   organic chemical methods;
 • an evaluation of ongoing quality as-
   surance programs;
 • development of a model to determine
   the type and level of QA/QC effort
   required for various uses of particular
   analytical methods.

  The full report was submitted in fulfill-
ment of Contract Number 68-03-2995,
by Radian Corporation. The research
reported here was conducted under the
sponsorship of the U.S. Environmental
Protection Agency (USEPA).
  This Project Summary was developed
by EPA's Environmental Monitoring and
Support Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at

  The Environmental Monitoring and
Support Laboratory, U.S. Environmental
Protection Agency {EPA), Cincinnati of-
fice, has the responsibility for developing
quality control (QC) procedures and lab-
oratory quality assurance (QA) programs
to support ongoing  analytical method
development  research  and  monitoring
programs. Radian Corporation was con-
tracted to review  current QA/QC pro-
grams*  and  develop  guidelines for
QA/QC  practices  for the USEPA 600
series methods for chemical analysis of
toxic organic pollutants.
  The primary objective  of the full report
is to provide guidance for choosing cost-
effective analytical QA/QC programs. To
this end, the full report is organized into
five sections,  with  two appendices. Ref-
erences are  provided  throughout the
report for amplification and follow-up by
the reader.

  This section presents  a general over-
view of the report  organization. Twelve
general references are provided.

General QA/QC  Principles
  This section discusses general con-
cepts and approaches found useful by the
quality control profession in over 50 years
of accumulated experience. The princi-
ples described are  qualitative, but serve
as guides to quantitative evaluations of
QA/QC programs.  They also are helpful
guides in starting  quality programs for
new test methods (where information
needed for quantitative decisions may be
lacking) or for choosing minimal programs
for methods whose  results  are put to
many uses.
*QA = Quality assurance, the system of activities
     whose purpose is to provide assurance that
     the quality-control job is being done effec-
 QC = Qualitycontrol.thesystemof activities whose
     purpose is to provide a quality of product or
     service that meets the needs of users

  The following concepts are discussed
in this section:
• Definition of Quality as FitnessforUse
• Total Quality Control
• Resource Allocation
• Process Control
• Measures of Analytical Quality
• Simplicity
  Seventeen references are provided to
the reader for further studies.

QA/QC Tools
  Commonly used QA/QC tools are dis-
cussed in this section in terms of-

• Purposes and potential benefits
• Information requiredtojudgeeffective-
• Qualitative guidance for effective use
• Sources of further information

Among the possible reasons for using a
quality control tool  are documentation,
appraisal, control or  improvement  of
quality,  and prevention of quality prob-
lems. Some tools serve more than one of
these purposes. The methods available
are not all suitable for every job.
  A brief subsection is devoted to  each
topic. EPA's QA audit category identifiers
for  measured  values  are  given where
appropriate. References are listed at the
end of each subsection for convenience.
  The following well-referenced discus-
sion topics are presented in this section:
• Blanks (5 references)
• Calibration (17  references)
• Control Charts (24 references)
• Interlaboratory Studies (15 referenc-
• Material Controls (6 references)
• Method Development (10 references)
• Performance and System Audits  (5
• Reference Materials (7 references)
• Replication (11  references)
• Sampling Procedures (11 references)
• Spike-Recovery Studies (3 references)
• Study Planning (5 references)
• Surrogate Compounds (2 references)
• Validation (5 references)

Measuring QA/QC Cost
  Measures of analytical quality, such as
bias and  precision,  are useful to the
laboratory for evaluating and maintaining
its performance. However, since factors
in addition  to  analytical  quality  often
affect the usefulness of results,  more
comprehensive criteria are  needed for
measuring  end-use  effectiveness. The
purpose  of  this section  is  to  present
methods for evaluating the cost-effective-
ness of particular QA/QC activities.
  The statistical tools needed to develop a
quality control program, based upon data
quality objectives (DQO) are presented in
the form of  20 equations, eight charts,
and two useful nomographs. Each topic is
presented with example calculations to
illustrate the solutions to quest ions, such

• How  many  replicate  analyses  are
   needed for  a single test to reliably
   detect a bias of specified size?

• How  many  replicate  analyses  are
   needed for  a single test to reliably
   detect a specified bias?

• What is the probability of detecting a
   serious contamination problem in the
   laboratory in a  single method blank

• How many sets of duplicate analyses
   are needed  in a specified period to
   reliably detect a specified increase in
   standard  deviation?

Choosing Cost-Effective
QA/QC Programs
  This section begins with the  premise
that in  many laboratories an analytical
method may be routinely applied to the
analysis of sample lots with different end-
uses and data quality objectives.
  In such a setting, a single  QA/QC
program cannot be  cost-effective for
every application. One reasonable way to
avoid requiring superfluous  efforts is to
establish a two-tier program  on  the
following basis:

• Minimal—QC steps needed regardless
   of use
• Additional—QC  steps tailored to end-
   use needs

  The cost-effectiveness of QA/QC pro-
grams can be improved further by basing
levels of QC effort in both the minimal and
additional  phases  on reasonable  QC
targets (as discussed in Section 4).  The
development of a minimal  program is
discussed in the first part of Section 5; the
selection of additional QA/QC procedures
is discussed in the final part of Section 5.
The EPA 600 series methods are used to
illustrate the principles discussed in these

  The first appendix  to the full report
describes the application of skip-lot qual-
ity control procedures. The basic idea of
skip-lot  procedures is that the amount of
appraisal  effort required  in a  quality
control program depends on the quality
being produced A process that produces
consistently high quality  requires less
monitoring than one that frequently ex-
periences quality problems. Skip-lot pro-
cedures provide objective rules for decid-
ing the frequency of appraisal needed.
  The second appendix addresses  the
design  and analysis  of spike-recovery
studies  In this appendix, statistical prop-
erties of percent recovery data, when
analytical bias and precision are propor-
tional to sample concentration, are des-
cribed. The impact of the presence of the
analyte of interest in the unspiked sample
(i.e., non-zero background concentration)
is examined and some of the  potential
pitfalls  in  the  interpretation of percent
recovery data  in method  development
and quality control applications are dis-

     L. P. Provost andR. S. Elder are with Radian Corporation, Austin, TX 78766.
     James E. Longbottom and Stephen Billets are the EPA Project Officers (see
     The complete report, entitled "Choosing Cost-Effective QA/QC Programs for
       Chemical Analysis," (Order No. PB 85-241 461; Cost: $16.00. subject to
       change) will be available only from:
            National Technical Information Service
            5285 Port Royal Road
            Springfield,  V'A 22161
            Telephone: 703-487-4650
     The EPA Project Officers can be contacted at:
            Environmental Monitoring and Support Laboratory
            U.S. Environmental Protection Agency
            Cincinnati, OH 45268
United States
Environmental Protection
Center for Environmental Research
Cincinnati OH 45268
Official Business
Penalty for Private Use $300

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