ENVIRO-CLEAN® solid-phase extraction cartridges

Hydrophobic phases

The most common hydrophobic phases are C8 and C18. The manufacturer offers a wide range of these cartridges with volumes ranging from 1 to 75 ml and sorbent weights of 100 to 5,000 and 10,000 mg respectively. Other phases in this group include C2, C30, phenyl and cyclohexyl.

Hydrophilic phases

Hydrophilic sorbents consist of a silica base bonded to carbon chains containing polar functional groups. Examples of phases with this functionality include pure silicon dioxide, diol and cyano-propyl phases. Compounds are retained on hydrophilic sorbents via polar interactions, including hydrogen bonds, π–π or dipole–dipole interactions. These types of interactions occur when the distribution of electrons between individual atoms in functional groups is unequal, resulting in negative and positive polarities. Polar-functionalised bonded silicas and polar adsorption media are typically used under normal-phase conditions.

Anion-exchange phases

Ion-exchange resins come in two different forms: strong and weak. The number of charges on a strong ion-exchanger remains constant regardless of the buffer’s pH. Weak ion-exchange resins exhibit pH-dependent functionality and, consequently, provide optimal performance only within a narrow pH range. For optimal interaction, both the compound of interest and the functional group on the bound silica must be fully charged. Ion exchange in SPE allows the desired anions or cations to be rapidly collected and then eluted from the solid phase.

Cation-exchange phases

Designed for the removal of cations (e.g. metal cations, amines, ammonium compounds). They are often used to purify solutions of ions that cause water hardness (e.g. calcium, magnesium) or to remove unwanted cations.

Copolymer

Copolymer sorbents consist of a silica matrix linked by two types of functional chains. One is an ion-exchange or polar chain, whilst the other is a hydrophobic carbon chain. UCT copolymer phases are manufactured such that equal proportions of each functional group are attached to the silica substrate, forming reproducible bonded phases and a unique chemical structure of the copolymers. This type of mixed-mode separation is useful when both neutral and charged compounds need to be extracted, and typically results in a purer final extract. This type of mixed-mode separation is useful when both neutral and charged compounds need to be extracted, and typically results in a purer final extract.

Polymeric DVB sorbent

Enviro-Clean® polymer-based extraction sorbents are manufactured from ultra-pure, high-quality cross-linked styrene-divinylbenzene polymer. These sorbents can be used in a variety of phases, similar to those used with silica-based sorbents. Options include standard ion-exchange functions. Enviro-Clean® particles have an average size of 30 microns and increased loading capacity. This greater capacity allows for a reduction in the required mass of the sorbent bed. Furthermore, the Enviro-Clean® sorbent eliminates the need for an initial column conditioning stage. All these characteristics ultimately result in cost savings for the end user.