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Carbonised molecular sieves are the strongest sorbents and are used to trap the most volatile compounds. They operate under a mixture of adsorption and molecular sieve principles, therefore their specific surface area is not the key indicator of their strength.
The size and shape of the analyte molecule and the size and shape of the particle pores determine the analytes that each sorbent is most suited to.
These sorbents are not very hydrophobic and, therefore, may require dry purging prior to desorption to remove excess water.
Due to their strength, carbonised molecular sieves are easily contaminated by higher boiling point compounds and should be protected by a front bed of weaker sorbent - except when used for diffusive sampling.
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