Advanced separation methods for complex samples

Rainwater is one of the natural elements that comes closest to being chemically pure: it comes from evaporation, and above the oceans is over 99.99% water, H₂O. Above land, and especially inhabited areas, pure water, an excellent solvent, becomes loaded with anthropogenic pollutants and bacteria. So much so that rainwater collected in downspout recovery cisterns must not be used for food.

As a result, the vast majority of compounds found in nature are mixtures. Separation methods are critical in chemistry to obtain pure compounds.

Separation methods are used to obtain large quantities of pure products. For example, the metallurgy industry extracts the desired metal from an ore that contains little of it; or the petrochemical industry produces, from crude oils, the tons of different fuels needed for different modern vehicles. The chemical industry produces a wide variety of compounds, in quantities ranging from milligrams (active pharmaceutical ingredients) to thousands of tons (fuels, fertilizers, plastics, detergents), using processes that involve very large-scale separation methods. These methods are briefly listed in this article.

Other separation methods are designed to detect minute quantities of a particular compound in different matrices: is this soil, this food, this air contaminated? Has this athlete taken a compound to dope himself? Does the composition of this company's product respect the patent registered by that other company? Was arsenic administered to Napoleon to hasten his death? Answers to these questions require advanced separative methods for complex mixtures. These methods are the subject of most of this article.

As English is the internationally accepted language of science, the acronyms for the techniques described are most often used in French. This is the case in this article.