Sample Prep Sorcery

It is striking that someone of Pat Sandra’s stature should need to highlight sample preparation as an issue – especially given that experienced practitioners should be acutely aware of its importance in terms of both time and potential analytical error. In “Three Wizards of Sample Preparation” (see tas.txp.to/0914/samplewizards) three esteemed colleagues provide some important insights on the topic. I’d like to share and discuss the comments that I found particularly interesting.

First, I was intrigued by the divergent importance attached to sample preparation by different analytical communities, specifically the gap between academia, instrument manufacturers and end-users referred to by Frank David. Sample prep is arguably most important to the end-users who deal with the challenges of analyzing large numbers of samples that demand accurate data on a day-to-day basis. If the importance of sample preparation is not sufficiently recognized in academia (and there are notable exceptions, think for example of Sandra’s development of SBSE), the reason may well lie in sample preparation not being considered “sexy” enough, to quote Hans-Gerd Jannsen. I agree that the situation is exacerbated by significant developments in instrumentation, especially MS, which has led to less emphasis being placed on sample prep. To some extent, this is understandable considering the limitations of sample prep (as the saying goes, the best form of sample preparation is no sample preparation). Due to a combination of these reasons, there is an unfortunate trend to underestimate the value of sample preparation and rely on instrumental performance to provide the required results. However, as also pointed out by Frank, errors made in sample preparation cannot be corrected later, whatever the instrumentation. Indeed, it is important to be aware of the limitations of even the most advanced instruments – electrospray ionization for example, even combined with highly selective MS/MS, is susceptible to ionization suppression, which can, in most cases, be avoided through judicious sample pretreatment.

A second area of concern raised by all three experts is the lag between sample prep developments and their implementation in regulated environments. This “conservatism” of accreditation bodies means that the benefits of improved methods are not realized in this environment. Again, this is partially understandable in light of the fact that methods need to be re-validated. But surely, replacing antiquated methods with techniques that have been extensively studied and optimized by researchers over many years is worth the effort.

The “Wizards” agreed on the most important developments in sample preparation, which brings me to my third point, the future of sample preparation: miniaturization, automation and higher throughput. Implied in miniaturization is the important move towards “greener” sample prep methods, which I’m sure we all agree is a very good thing (think of Pat’s comment on the excessive use of dichloromethane).

Finally, the question may (and indeed has been) asked: does sample preparation get the attention it deserves? Based on the comments of the Wizards, the answer in not clear-cut. On the one hand, it is clear that some research groups in academia and industry certainly appreciate the importance of sample prep; at the same time, this is not universally true across the board, and examples of impractical, or worse, illogical, sample preparation methods abound.

The question then becomes how the situation may be improved. I agree with Frank’s view that much of this is simply “down to a lack of expertise” – that the problem is not a lack of “methods and equipment, but rather education”. This is surely something that can be improved – as David Benanou points out: “the importance of sample prep should and must become more prominent in universities”. It is unfortunately true that in many academic institutions sample prep is included only as an afterthought in the curriculum, with much more emphasis placed on advanced chromatography and MS. If graduate students were better trained, they would transfer an appreciation of the importance of sample prep to industry and academia as the next generation of analytical scientists…

Forums like Riva, which enable discussions between leading scientists in the field, can only contribute to giving sample preparation the attention it deserves. And this is surely one of the intended – and very important – outcomes of Pat Sandra’s comments.