Macroporous Based Resin

Macroporous resins are compatible with organic, aqueous, protic and aprotic media. They have low swelling characteristics, making the resin ideal for use in fixed bed applications. Stratospheres and QuadraPure are widely used macroporous based resins. The QuadraPure consists of functionalized macroporous polystyrene beads (Figure 9.7). 

Macroporous resin beads, due to their mode of preparation, consist of a macroporous internal structure and highly cross-linked areas (>5%). The latter impart the resin with rigidity, whereas the porous areas provide a large internal surface for functionalization, even in the dry state. These macroporous polystyrene-based resins are subsequently modified in various manners, which render them compatible with numerous organic solvents. Furthermore, they show high resistance toward osmotic shock, but can be brittle when not manipulated carefully. 

Besides chemically bonded phases on silica gel supports microparticulate macroporous polymer resins also have been used in the analysis of alkaloids (see Chapters 7 and 8). A disadvantage of macroporous polymer resins is that they are not as rigid as the reversed-phase materials based on silica gel. In addition they may shrink or swell slightly - depending on the composition of the mobile phase. On the other hand they are more stable than chemically... 

In addition to the silica or polymer based resins mentioned above, polymer based resins with specific chemistries at the functional group have also been widely used as palladium scavengers for synthetic organic reactions. These include macroporous polystyrene-bound trimercaptotriazine (TMT). It, along with the thiol resin, has been found to be highly effective in reducing the concentration of palladium in both aqueous and non-aqueous solutions [18]. 

Preparation of a macroporous ionexchange resin based on styrene and dlvlnylbenzene ... 

Adsorption chromatography is an efficient way to isolate organic acids from large volumes of water. The nonionic, macroporous, Amberlite XAD-8 and the weak-base anion-exchange resin Duolite A-7 are two resins well suited for this purpose. These resins have been successfully used to extract organic acids from natural waters at sites where it was necessary to process thousands of gallons of sample. 

Another adsorption system evaluated was a high-volume, high-pressure, macroporous-resin-based concentrator system designed to provide a 10,000-fold concentrate. This system used four stainless steel columns in series. Columns one through four were filled with AG MP-1 (Bio-Rad), AG MP-50 (Bio-Rad), XAD-2 (Rohm and Haas), and XAD-7 (Rohm and Haas), respectively. Unlike the other adsorption processes, a pump system was employed for both the adsorption and desorption phases of the evaluation. The use of acetonitrile as the elution solvent permitted UV monitoring of the eluant. 

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