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Why Representative Sampling Is Important

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News

Why Representative Sampling Is Important

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Modern analytical methods are extremely sensitive and capable of detecting minute quantities of compounds in the aliquots they analyse. However, this may be of limited or even no practical use if the samples from which they were derived are not representative of the original materials or the environment they came from.

Consider, for example, the task of quantifying the level of contamination by GMOs in a ship’s cargo of feed intended for animal consumption, e.g. rape seed, grain. The cargo weighs thousands of tons and it is, of course, impossible to use all of this for analysis, so a “sample” must be collected. However, here lies an often-unrecognised problem: nearly all materials are made up of a mixture of constituents—they are “heterogeneous”—and the contamination in the ship’s cargo will, almost certainly, not be distributed evenly throughout.


In fact, all materials that one might find in practical usage in science, technology and industry are heterogeneous—it is only a matter of degree. Sampling an analytical aliquot from heterogeneous materials in a justifiable, representative manner constitutes a massive hidden elephant in the room of analysis! How then can one know how to sample and how can one be sure that the sample will be truly representative of the whole? The answer is to be found in the specific rules found in the Theory of Sampling (TOS).


A new book, Introduction to the Theory and Practice of Sampling, introduces all the necessary concepts to develop the practical procedures needed and shows how a wide range of sampling scenarios can be tackled. This technical ability is, of course, critical for all of those responsible for sampling in the frontline and subsequent mass reduction.


The book is written by Professor Kim H. Esbensen, who has 20 years of experience in teaching the TOS and applying it to a wide range of technological and industrial cases. This book is deliberately designed to present a subject, which many believe is complex and difficult, in an easy-to-follow form and to guide the reader through the complete foundation needed so that “anyone” can master the core elements of the TOS. The book features numerous schematic diagrams and illustrations, as well as drawings and photographs to help clarify important issues. It also contains many references that the interested reader can use to enhance their knowledge and sampling skills set.


The TOS has long been embraced by critical industries such as mining and minerals processing, coal and cement sectors where there are clear and substantial economic reasons to do so. However, the TOS should be far more widely appreciated and used in many other sectors of society as well. Indeed, from the point of view of the universal occurrence of heterogeneous materials, this book argues and demonstrates forcefully that representative sampling is essential for almost all analysis to be valid. How otherwise can we be confident of the analytical results and their implications in manufacturing, pollution, food and agriculture etc.?

Reference
Introduction to the Theory and Practice of Sampling. Kim H. Esbensen. ISBN: 978-1-906715-29-8. Published by IM Publications Open, Charlton Mill, Charlton, Chichester, West Sussex PO18 0HY, UK.

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.

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