IJCA - Volume 2 - Flipbook - Page 58
58 The International Journal of Conformity Assessment
discards (e.g., slag or dross). In trade, unexpected
contamination during transport or handling is very
common. Sometimes, unexpected developments
may happen due to accidental or deliberate
contaminations. Even if these types of problems
had been handled at another time, such information
may not be readily available in the public domain.
In all these situations, the laboratories were under
pressure and had an obligation to conduct studies
or investigations to develop methods of testing
and achieve possible conclusions and solutions.
Laboratory personnel have to use all their experience
and knowledge to first understand the problem, to
identify the possible ways and test methods that can
provide conclusions.
Clear Understanding Is Critical
for Reliable Results
The author has witnessed such unexpected
requirements in his experience. One recent example
involved a wheat export from India to Italy where
the consignment was rejected at the discharge
port, citing the presence of rubella, a disease never
expected on a food grain. Now who knows, to be
on the safe side a country might make it a norm to
test a wheat export for this disease. Similarly, this
happened with testing for melamine, which began
with milk then extended to every food commodity,
and also testing for Sudan dyes, which started off
with chili powder and then other food products.
While working out test methods for such situations,
which the author terms as challenges, a certain
amount of risk is involved, since there is no prior
history and no reference samples or reference
standards for comparison. Reliability of the results
can be achieved only by a clear understanding of the
situation, products and test methods. Sometimes, it
could be a small deviation from a standard method
as such deviations are allowed per ISO/IEC 17025,
provided the deviation has been documented,
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technically justified and accepted by the customer. It
also could be an established method (or combination
of established methods) used for some other
purpose and applied for the present needs to the
situation or requirement. At times, it could result in
an entirely new laboratory developed method. All
the laboratory is expected to do in such situations is
validate the method in as many ways as possible to
support confidence in the results.
Validation of such laboratory-developed methods is
possible only through:
a. understanding the theoretical principles of the
method and practical experience;
b. systematically assessing the factors influencing
the result;
c. confirming no interference from the matrix of the
sample or test object;
d. ascertaining the measurement range, precision,
and robustness;
e. evaluating measurement uncertainty; and finally,
f. ascertaining whether the performance
characteristic of the validated method is relevant
to the intended need and consistent with specific
requirements.
The above validation adequately satisfies the
requirement of ISO/IEC 17025:2017, Note 2 under
Clause 7.2.2.1.
Though antiquated now, the statement in the 2005
version of ISO/IEC 17025 in Note 3, Clause 5.4.5.3
is practical and sensible and holds relevance
in this regard. It states: “Validation is always
a balance between costs, risks and technical
possibilities. There are many cases in which the
range and uncertainty of the values (e.g., accuracy,
detection limit, selectivity, linearity, repeatability,
reproducibility, robustness and cross-sensitivity)
can only be given in a simplified way due to lack of
information.”
