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These are non-specific carbon sorbents widely used for trace level applications due to their minimal artifact levels. They range from the very weak to medium/strong sorbents and are used for a wide range of VOCs and sVOCs. They are fairly hydrophobic and therefore suitable for sampling under humid conditions. They can however contain trace levels of metals which means they are not 100% inert. This makes them less suitable for some labile or highly reactive species e.g. mercaptans and monoterpenes.
Physically, these sorbents are very friable i.e. they are susceptible to fines formation, particularly when subjected to mechanical shock. Avoid dropping tubes packed with carbon blacks and ensure they are adequately protected during transportation. Overcompression of these sorbents during packing can also lead to high back-pressure. In extreme circumstances sorbent tubes may become blocked and will need repacking.
Although generally considered to be non-porous, the strongest graphitised carbon sorbents (i.e. Carbopack X, Carbograph 5TD) do exhibit microporosity which improves the ability of these sorbents to trap ultravolatile compounds. These sorbents therefore provide a bridge between the graphitised carbon blacks and the stronger carbonised molecular sieves.
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