Fit for Purpose A Customers View
Bernd Wenclawiak
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Analytical measurements should be
made to satisfy an agreed requirement
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Analytical measurements should be
made using methods and equipment
which have been tested to ensure
they are
fit for purpose
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Staff making analytical measurements
should be both:
qualified and competent
to undertake the task and
demonstrate that they can perform
the analysis properly
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
There should be a regular independent
assessment of the technical
performance of a laboratory
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Analytical measurements
made in one location
should be consistent
with those made elsewhere
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Organizations making analytical
measurements should have well
defined quality control and
quality assurance procedures
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Method validation is an important
requirement in the practice of
chemical analysis
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
What is Validation?
 Confirmation by examination and
provision of objective evidence that
the particular requirements for a
specified intended use are fulfilled
ISO 8402 (1994)
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
What is Method Validation? - 1
 The process of establishing the performance
characteristics and limitations of a method
and the identification of the influences which
may change these characteristics and to what
extent.
 Which analytes can it determine in which
matrices in the presence of which
interferences?
 Within these conditions what levels of
precision and accuracy can be achieved?
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
What is Method Validation? - 2
 The process of verifying that a method
is fit for purpose, i.e. for use for solving
a particular analytical problem
 This means the method must be
suitable
 Method validation is not solely the
process of evaluating the performance
parameters
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
The Method Validation Process
Implies:
 the use of equipment within its
specifications
 that the operator is fit for purpose
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Why is Method Validation
Necessary?
 Importance of analytical
measurement
 The professional duty of the
analytical chemist
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
When should Methods be
Validated ?
 Comparing methods
 Replacement of instruments
 Change of operator
 Other significant changes
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
How should Methods be
Validated?
 Who carries out method validation?
 Deciding what degree of validation is
required
 The analytical requirement
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Choosing, Developing and Evaluating Methods
Problem requiring
chemical analysis:
Set analytical
requirement
Develop
method
Yes
Identify existing
method or develop
new method
Method validation consists of this
evaluation stage, together with any
performance parameters that may
be evaluated under method
development
„Fit for purpose...“ . Regardless of
what existing performance data
may be available for the method,
fitness for purpose will be
Evaluate
method – fit for
purpose as used in
the laboratory
Yes
No
Further
development
feasible?
Yes
No
Relax
analytical
requirement
?
No
Analytical work
proceeds
Unable to do work –
subcontract?
Analytical requirement
re-stated in terms of
what has been
accomplished
En
d
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
How should Methods
be Validated?
 Who carries out method
validation?
 Deciding what degree of
validation is required
 The analytical requirement
 Method Development
 The different performance parameters
of a method and what they show
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
How should Methods be Validated?
 The different performance parameters of a
method and what they show






Confirmation of identity and selectivity/specificity
Limit of detection
Limit of quantitation
Working and linear ranges
Accuracy
Trueness
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
How should Methods be Validated?
 Interpreting bias measurements
Measured value
(laboratory mean)
True value
Total bias
Interlaboratory
mean
Laboratory bias
Method bias
Note: Laboratory and method biases are shown here acting in the same direction.
In reality this is not always the case
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
How should Methods be Validated?
 The different performance parameters of a
method and what they show







Confirmation of identity and selectivity
Limit of detection
Limit of quantitation
Working and linear ranges
Accuracy
Trueness
Interpreting bias measurements






precision
repeatability
reproducibility
sensitivity
ruggedness or robustness
recovery
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
How should Methods be Validated?
 The different performance parameters of a method
and what they show













Confirmation of identity and selectivity
Limit of detection
Limit of quantitation
Working and linear ranges
Accuracy
Trueness
Interpreting bias measurements
precision
repeatability
reproducibility
sensitivity
ruggedness-robustness
recovery
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
The Tools of Validation













Blanks
reagent blanks
sample blanks
Samples/test materials
fortified materials/solutions
spiked materials
incurred materials
independently characterised materials
(Measurement) Standards
Reference Materials
Certified reference materials
Statistics
Replication
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Using Validated Methods
 Two issues to consider:
 are existing validation data adequate
 is the analyst sufficiently competent
can he achieve the performance level claimed in
the method?
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Rules Recommended to Ensure
Acceptable Performance
 Analyst should be familiar with method before
using it for the first time
 Work firstly under supervision
 get training
 think ahead of process, solutions etc required
 Make an assessment how many samples can
be handled at a time
 Make sure everything needed is available
before work starts
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Using Validation Data
to Design QC
 Internal QC
 External QC
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Using Validation Data
to Design QC
 Internal QC includes:







blanks
chemical calibrants
spiked samples
blind samples
replicate analysis
QC samples
control charts (recommended)
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Using Validation Data to Design
QC
 External QC
 e.g. proficiency testing (external quality
assessment)
 participation in proficiency testing schemes
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Documentation of Validated Methods 1
 When the validation process is complete
document the procedures of the method
(also important for auditing and evaluation purposes)
 With appropriate documentation
 reuse of method is more consistent
 uncertainty contribution is decreased
 Test quality of documentation with a
competent colleague
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Documentation of Validated Methods 2
 Standard guidance for documentation is
found in ISO 78 series
 “house style” is also adequate
 Documented methods form an important part
of a lab’s quality system
 document control







is documentation complete
authorized for use
which version
which date
author
copyrights
when last updated
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Method Documentation Protocol
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Implications of Validation Data for
Calculating Results and Reporting
 Translate data in results to solve customers
problem
 Consider:
 are observed differences significant?
precision data for repeatability and reproducibility
 Quality controls confirm method is in control
based on validation data producing meaningful results
 Estimation of measurement uncertainty enables
expression for level of confidence
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching
Implications of Validation Data for
Calculating Results and Reporting
 The analyst needs access to validation
data to support validity of results
 The customer may not need or understand
it
 Information about uncertainties might
not be understood by everybody
(lawyers)
 When required: uncertainty should be
reported (confidence limits e.g. 95 %)
Wenclawiak, B.: Fit for Purpose – A Customers View
In: Wenclawiak, Koch, Hadjicostas (eds.)
© Springer-Verlag Berlin Heidelberg 2003
Quality Assurance in Analytical Chemistry – Training and Teaching