Specimen preparation is the cornerstone of successful biological X-ray microanalysis. A damaged or compromised specimen cannot be ‘recovered’ by sophisticated analytical hardware or software, or even by a skilled operator. But what constitutes a ‘good specimen’ or an ‘acceptable degree of damage’? Is there such a thing as ‘the ideal preparative procedure’? Answers to these fundamentally important questions are explicitly or implicitly offered in the chapters in this section of the book. However, two general observations should be made at this juncture.

First, there is no single ideal preparative procedure that meets all the requirements of the biological electron probe X-ray microanalyst (even if we confine our considerations to thin specimens of soft tissues). The starting point must be the nature of the biological problems that are to be tackled. Once this has been clearly defined then a suitable preparation procedure may be adopted, but even then the question (and thus the analytical objectives) may need to be modified in the light of the anticipated level of preparative damage. Measuring electrolyte concentrations in a small cohort of distinctive cells lying some distance beneath the surface of a complex tissue is a good example of a ‘real microanalytical problem’, as distinct from the analysis of well-chosen model systems. Electrolyte analysis requires cryofixation to limit redistribution, but the quality of freezing will not be high in deep cells. So the prospect of analysing compartments finer than ‘nucleus’ and ‘cytoplasm’ in such preparations may be unrealistic.