Isolation of particular species

The relationship between the polarity of solvent and the affinity for sorbent phases can be utilised in separating petroleum fractions into component 

The aliphatic and the aromatic fractions can be analysed together or separately. Confusion has arisen in the past with regard to terminology. Methods for the determination of mineral oil have been confused with that of TPH. To avoid confusion a definition that utilises the above clean-up as a principal component of the method is proposed mineral oils are a group of compounds with the carbon number C10-C44, which are not retained when passed through a silica column using a non-polar solvent such as n-hexane . 

Chemically, mineral oils consist of aliphatics (n-alkanes, iso-alkanes and cycloalkanes). Interfering substances, such as elemental sulfur, can be dealt with by either passing the extract over activated copper, or for Soxhlet, the copper can be added at the extraction stage. 

---