Clean Up Hydrophobic

MECHANISM OF HYDROPHOBIC BONDING

Compounds are retained by non-polar interactions from polar solvents or matrix environments.  They are bound by dispersion forces/van de Waals forces.  Elution, or disruption, of the non-polar interactions is achieved by solvents or solvent mixtures with sufficient non-polar character.  Some polar solvents, such as acetonitrile have enough non-polar characteristics to disrupt nonpolar binding to cause elution of a compound from the sorbent.  Methanol can be used as well, although it should be noted that it will take off both polar and non-polar analytes of interest as well as interferences.

These sorbents are composed of a silica backbone bonded with hydrocarbon chains.  It is used to extract compounds which exhibit non-polar or neutral characteristics from complex matrices.  The C18 phase is the most widely used for non-polar interactions because of its non-selective nature; C18 will extract a large number of compounds with differing chemical properties.  To enhance selectivity, UCT offers a variety of hydrophobic sorbents.  Several chain configurations are available as well as endcapped and unendcapped versions.

One can extract alkanes, alkenes, aromatic and neutral compounds using Clean Up^® sorbents.  These compounds are washed with aqueous solvent with some polar organic solvent included.  The compounds are then eluted with solvent ranging from non-polar to polar organic solvents depending upon the analyte.

HYDROPHOBIC SORBENTS & STRUCTURES

Sorbent                                        Structure

C2 Ethyl                                        -SiCH₂CH₃

C4 n-Butyl                                    -Si(CH₂)₃CH₃

C8 Octyl                                        -Si(CH₂)₇CH₃

C18 Octadecyl                            -Si(CH₂)₁₇CH₃

C30 Tricontyl                               -Si(CH₂)₂₉CH₃