Separation Science – GC-MS, GC-HRMS, GCxCC, GCxGC-MS, GCxGC-HRMS

What is Separation Science?

Separation science is the science used by a laboratory to separate a mixture of components into batches of related components. This can be as simple as extracting all of the oil from a sea water sample (Gulf of Mexico oil spill) or as complex as separating all 16,000+ components from a diesel sample. This can be done by applying many difference approaches from the extremely simple such as gravity or density, distillation or evaporation to more complex approaches such as GC and GCxGC.

When a mixture is created, any components that will react will form new substances, the rest remain the same. Some will degrade fast, others will degrade slowly over time. However, once the mixture “settles”, generally no further reactions occur, nor will bonds be created. At such a time mixtures can then be separated back into their component parts. An easy example is using colours, where yellow and blue will make green. With the right combination of chemicals it is possible to separate green back into blue and yellow.

Of course, once you have separated the substances, you will need to identify these to confirm that you have performed the task properly.

What is Chromatography then?

Separation science and chromatography are often used interchangeably in the modern laboratory context as the older techniques have been ingrained in the sub-conscious. For example, using a centrifuge is a form of separation science that is so common that it is “no longer” seen as a separation science technique.

Chromaography is derived from the Greek words for colour, “chroma” and writting “graphein”. A russian scientist, Mikhail Tsvet, developed this technique in 1900 when working on pant pigments such as carotenes and chlorophyll. As these pigments have different colours, the act of separating these on a paper made the process appear to be writing colours on the paper, hence the name. This is still a beautiful experiment that can be duplicated.

The field of chromatography nowadays underpins the sciences of chemistry and biology, as well as the bridging field of biochemistry and naturally engineering. Most modern fields such as genomics, DNA fingerprinting, drug discovery and even nutrition and diet owe their modern existence to

Separation science is also referred to as “chromatography”, a term which combines the Greek words for colour (“chroma”) and writing (“graphein”). The various techniques and methods which underpin separation science inform the study of chemistry and biology, as well as engineering. Major advances in separation science have enabled biologists, chemists, pharmacists and environmentalists to make breakthroughs of their own. Genomics, drug discovery, DNA fingerprinting and ultra-trace residue analysis, for instance, would not be possible without recourse to the findings generated by separation science.

Different types of separation science: preparative and analytical chromatography

Separation science, or chromatography, can be analytical or preparative. Analytical chromatography relies on small amounts of material and strives to measure the relative amounts of analytes in a mixture. No attempt is made to ready the material for future use.

Preparative chromatography, on the other hand, seeks to separate a mixture into usable component parts. Preparative chromatography can be done on a small scale or an industrial scale.

Separation processes

Separation processes convert mixtures into their constituent parts. Barring a handful of exceptions, almost every element and compound known to man is found in an impure – or mixed – state naturally. Before these impure substances can be put to good use, they must be separated into their constituent parts. In some instances, separation may result in a number of pure components. However, at other times, incomplete separation will suffice. Naturally occurring crude oil, for example, contains a mixture of different hydrocarbons and impurities. The refining process separates these substances into other, more valuable mixtures, such as gasoline, natural gas and chemical feedstocks. A series of separations takes place before the desired end products are considered usable.

In general, separations are based on differences in physical or chemical properties, such as shape, density, size, mass and chemical affinity. When no clear difference can be identified, multiple operations are generally performed to achieve the desired separation.