# Methacrylate Polymer Monoliths for Separation Applications
## 3 Applications of Methacrylate Polymer Monoliths in Separation Science
### Separation and Pre-Concentration of Chemical Species
#### 3.1.2 Chemical Separations
A hexyl acrylate monolith was synthesized via photo-polymerization by [PERSON] _et al._[122] and used in the pre-concentration and separation, via CEC, of nine PAH compounds. Good separation of the mixture was achieved, while pre-concentration factors of up to 100 were reported. Interestingly, the monolith was also prepared in a glass microfluidic channel, and separation was achieved in less than four minutes, with the number of plates estimated to be around 200,000/m and concentration factors of around 200 were calculated. Methacrylate monoliths have also been used for the separation of racemic pharmaceutical compounds. The pharmaceutical industry is risk and change averse, so it would be slow to adopt a new technology, especially one which might be deemed to be evaluating/improving product quality. However, a recent report by [PERSON] _et al._[129] illustrated the effective separation of a number of chiral pharmaceutical compounds including diprenolol, bufralol, carbuterol, cizolertine, desmethylcizolertine, eticlopride, ifosfamide, 1-indanol, propranolol, tebuconazole, tertatolol and _o_-methoxy mandelic acid. The separation was carried out under reverse phase conditions. Twelve distinct classes of compounds were investigated, as well a number of other compounds listed as miscellaneous, for example, the mandelic acid based compounds. The monoliths contained a cyclodextrin functional group, which facilitated the chiral separations, it was also noted that the separations used more environmentally friendly solvents, and that the fabrication of the polymer monolith was easier and quicker than the fabrication of the silica monoliths also reported in the same contribution. [PERSON] and co-workers [130] prepared a poly (6-azido hexanoic acid (AHA)-_co_-propargyl methacrylate-_co_-ethylene dimethacrylate) monolith via the CuAAC click reaction (as discussed above), for the separation of alkyl-benzenes, phenols, anilines and PAHs. Good separations were obtained for all of these compounds however the plate number for the PAH separation was relatively low (21,000/m-28,000/m). Other examples of chemical analytes separated using methacrylate monoliths are phenols, xylene and bi-phenyl [131], anilines (using ion exchange) [132], metal ions (Mn, Co, Cd, Zn and Cu) [32], benzoic acid derivatives [133], as well as capillary liquid chromatography of aflat [50], acids and bases [134]. The extraction of metal ions [32] is one of great importance in environmental chemistry, however it was noted by the authors in this contribution that copper could not be isocratically eluted from the monolith in any reasonable length of time. However, the monolith appears to be suitable for the separation of other divalent metal ions. Figure 10: Chromatogram showing separation of a mixture of PAH compounds, on low density methacrylate monolith. Key: (1) thiourea; (2) naphthalene; (3) fluorine; (4) anthracene; (5) pyrene; (6) benz(a)anthracene; and (7) benzo(a)pyrene. Reprinted with permission from [35], Copyright (2005) American Chemical Society.