Definition
Untestable/deviating
samples are items which have been received by a laboratory, but which are not
in an appropriate condition to truly reflect the original sample. This could be
due to the samples not being handled correctly during transport or in the way
prescribed in the relevant standard or that lack essential information for a
quality analysis to be undertaken. Consequently, the validity of the reported
results may be jeopardized.
Such a sample might:
- not been preserved
adequately (e.g. not cooled, not acidified),
- have exceeded its maximum
preservation time,
- in the case of
microbiological analyses, lack the date and time of sampling,
- be denatured through
heat, light or humidity,
- have rotted or suffered
microbiologically, or
- have become cross
contaminated.
Background [1]
In the past assessment
teams of the Dutch Accreditation Council (RvA) identified major problems
regarding the handling of untestable/deviating samples by ISO/IEC 17025
accredited environmental testing laboratories. In each case these findings were
recognized as major non-conformities by RvA.
At the end of 2003, the
Dutch EUROLAB organisation FeNeLab conducted a “blind” inter-comparison on the
handling of untestable samples by ISO/IEC 17025 accredited laboratories. None
of the laboratories included a clear disclaimer in their reports and on only 2
occasions a vague statement was included.
Consequently, RvA informed
the EA Laboratory Committee about these results and requested that the National
Accreditation Bodies (NABs) should take corrective action. In the meantime,
most of the accreditation bodies in Europe have reacted, often by
informing their assessors accordingly.
Requirements of ISO/IEC
17025:2017 [2]
Clause 7.4.3 of ISO/IEC
17025 [2] requires:
“Upon receipt of the test
or calibration item, deviations from specified conditions shall be recorded.
When there is doubt about the suitability of an item for test or calibration,
or when an item does not conform to the description provided, the laboratory
shall consult the customer for further instructions before proceeding and shall
record the results of this consultation. When the customer requires the item to
be tested or calibrated acknowledging a deviation from specified conditions,
the laboratory shall include a disclaimer in the report indicating which
results may be affected by the deviation.”
Clause 7.8.1 requires in
general that “the results shall be provided accurately, clearly, unambiguously
and objectively, usually in a report (e.g. a test report or a calibration
certificate or report of sampling) and shall include all the information agreed
with the customer and necessary for the interpretation of the results”.
However, the standard also
sets requirements regarding the competence of laboratory personnel to evaluate
the significance of deviations (clause 6.2.3).
Recommendations
When a sample is taken by
the customer or on the customer’s behalf by an external provider and
transferred to the laboratory, the laboratory cannot be responsible for
verifying if the sample was taken in accordance with the relevant requirements.
Nevertheless, a competent laboratory must not ignore any obvious observations
concerning any adverse condition of the sampling process which might jeopardise
the validity of the results. Just a statement that the results relate to the
item tested/analysed as received, which is used by many laboratories is
certainly not enough. In such a case, the laboratory shall contact the customer,
inform them of the problem and ask for further instructions. Clause 7.1.4 has
to be considered in this context.
When the customer requires
the sample to be tested as the laboratory received it, it is the responsibility
of the laboratory to perform the test. In such cases, the report shall include
a disclaimer which clearly notices that deviations from the relevant standard
were observed and that the validity of the results can be affected by these
deviations. This general finding could be further specified e.g. by stating
that the sample was supplied in packing which was inappropriate for the
relevant analysis or that the sampling date was unknown or that the sample
condition had deteriorated. By such an action the laboratory complies with the
requirements and the intentions of ISO/IEC 17025.
Example
Disclaimer
The sample/item (ID: xy)
showed a deviation from the normal/original state (description of the state).
Therefore, the validity of the corresponding test results (marked with “**”)
can be affected.
Conclusions
When a competent laboratory
receives an untestable/deviating sample it shall ask the customer for further
instructions. This action offers support to customers concerning sampling and
the transfer of samples and may reduce the occurrence of untestable/deviating
samples considerably.
The use of disclaimers in a
test report in cases when the customer requires the testing of untestable
samples might cause competitive disadvantages for an individual laboratory.
Preferably, it should be subject to an agreement within the laboratory
community of a specific branch or in a specific region. Such an agreement
should clearly be supported by the respective national accreditation body or by
notifying authorities.
References
[1] EA Laboratory Committee,
Handling of deviating samples
by ISO/IEC 17025 accredited laboratories – Final Report February 2006, EA LC
(06)27
[2] ISO/IEC 17025:2017,
“General requirements for the competence of testing and calibration
laboratories”
