Objectives: Diagnostic samples are exposed to a spectrum of variables during transport to laboratories; therefore, the evaluation of a rather comprehensive stability profile of measurands is warranted. While appropriate testing standards have been established for pharmaceuticals and reagents, this is not the case for diagnostic samples. The aim of our work was to develop and evaluate a protocol applicable to diagnostic samples.
Methods: An isochronous approach with representation of temperature and exposure duration in a two-dimensional matrix was established. The deviations of the measurement results from the baseline associated with the exposure are evaluated with respect to the measurement uncertainty of the analytical measurement procedure applied. Variables of the experiment are documented in a standardized matrix. As a proof-of-concept, we profiled the stability patterns of a number of measurands at four temperature levels over up to 72 h in primary serum sample tubes.
Results: The protocol proved to be workable and allowed the description of a comprehensive stability profile of a considerable number of compounds based on 21 small-volume primary samples collected from each volunteer and exposed according to this protocol.
Conclusions: A straightforward and feasible isochronous protocol can be used to investigate in detail the effects of different pre-processing conditions on the stability of measurands in primary samples during transport to diagnostic laboratories. This is of significance as pre-analytical logistics become increasingly important with the centralization of analytical services.
Keywords: isochronous; pre-analytical processes; sample stability; sample transport.
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