The Weakest Link
The chemical analysis chain is only strong if the quality system takes into account each and every link – including those that can sometimes be neglected or forgotten.
Henk van 't Klooster |
It gave me pleasure to read and recognize the provocative remarks on sample preparation that my old colleague and friend Pat Sandra delivered at Riva 2014 (see tas.txp.to/0914/samplewizards). Some 20 years ago, when Pat and I collaborated in a research network as part of a European project, we had the same discussion. A starting point back then, as I saw it, was that chemical analysis could be described as a cyclic process. The last step – interpretation and evaluation of the results of the analysis – should eventually provide an answer to the problem or question at hand. If the answer is not satisfactory, either in the opinion of the laboratory manager (the internal client) or in the judgement of the customer (the external client), the analytical cycle can be followed again, after adaptation of one or more steps.
Like any chain, the chemical analysis chain is only as strong as its weakest link. And I believe that the weakest links in the analytical process are those that are not necessarily recognized as part of chemical analysis at all. Forget separation, detection – and even sample preparation – as the weak links in many cases. Rather, it is the steps that precede sample preparation – the ones that often take place outside the analytical laboratory – that are to blame. Let’s not forget the selection of the object(s) to be sampled, the design of the sampling plan, and the selection and use of techniques and facilities for the collection, storage and transportation of samples (all of which are particularly relevant in the environmental field).
The quality of the chemical information produced should always be the central issue. The main criteria being the utility and the reliability, which are closely related to the margins of uncertainty in the measurement results, regarding both the identity and the concentration of the target components. With respect to these criteria, minimum requirements are generally set by the customer and usually deduced from a previously specified purpose. But when an analytical laboratory is not responsible for the sampling, the quality management system does not often even account for these weak links in the analytical process!
In my view, quality control and quality assurance should take account of every single link of the whole chain of chemical analysis, from sample choice through to the evaluation of results. In this regard, I recognize the sentiments of Frank David, who stated that a lack of education and expertise is problematic not only at the laboratory level, but also at the management level. It seems to me that not much has changed in this respect over the last two decades. After all, a laboratory quality system is only effective if workers at all levels of an organization are aware of the quality that they are supposed to deliver to their internal and external clients. And that requires permanent education for all.