Everything in the world has an end, except the universe, which had no beginning and will have no end. Therefore, generally speaking, there is a limit to analysis, and there is no doubt about that. If we learn to determine the chemical nature of separate atoms of elements or molecules of a chemical substance, we may consider that the limit has been reached.

But that is not what we wanted to point out. As late as the forties of our century, some twenty-five years ago, chemists could analyse most impurities if their content in the principal substance was of the order of 0.01-0.001 per cent, and this suited almost everyone. But nowadays science and technology progress at such a terrific rate that by the early sixties it was already necessary to determine about one thousand billionth (10^�12) of a per cent of an impurity. But at that time we were only approaching such sensitivities in determining individual elements. At present there are already several elements and their compounds which we can determine in such quantities, thanks, primarily, to the methods of activation analysis, gas chromatography and mass-spectrometry, which enable scientists to determine such �trifles.�

The requirements imposed on impurity analysis will continue to mount steadily. Academician I. Alimarin, a renowned Soviet scientist, believes that the requirements for materials with respect to purity tend to such a limit where it will be necessary to determine single atoms of the impurity, i.e, amounts of substance of the order of 10^�23 gram. This difficult task will have to be coped with by physicists and chemists jointly. It has been solved so far for radioactive atoms. We can already determine the radioactive atoms of some chemical elements singly. However, the sensitivity of determination of the stable atoms and their compounds is still far from the limit. And here methods of analysis still await those who will succeed in �filling in� this �blank.�

---

< back     next >

index