Preparation of Biological Samples for X-Ray Microanalysis

Any preparative technique for x-ray microanalysis must result in reasonably recognizable structural detail, while at the same time preserving in situ the elemental constituents one wishes to analyze. This is frequently difficult, and some elaborate and ingenious preparative techniques have been devised to achieve this goal. In many respects the principles of the preparative techniques for x-ray microanalysis are not dissimilar to those used in scanning electron microscopy. The important difference is that the methods of preparation, while seeking to preserve ultrastructure, should not achieve this goal at the expense of the soluble cell constituents. In the discussions that follow it is not intended to provide innumerable recipes which could be applied to specific biological systems, but rather to consider the principles underlying the methodology and thus allow experimenters to devise their own methods for the particular sample in question. The subject is not new, and while an attempt will be made to give details of some of the more recent advances, reference should be made to the earlier studies and collected papers by Hall, Echlin, and Kaufmann (1974), Echlin and Galle (1976), Chandler (1977), Echlin and Kaufmann (1978), Morgan et al. (1978), and Lechene and Warner (1979), which provide recipes for specific biological samples.