## 2 Photo-Grafting Reactions
### Monolithic Columns with Bonded Ligands  
Boronate affinity phases are used to selectively extract molecules with 1,2- and 1,3-_cis_-vicinal diols, which are common to most carbohydrates [73]. [PERSON] _et al._ used two approaches in the preparation of boronic acid columns and compared both co-polymerization of GMA and photo-grafting of poly(GMA) grafts to a monolith surface [73]. The boronate affinity columns demonstrated the retention of ribonucleosides, with an increased affinity in the photo-grafted column. This was due to an increase in the surface density of grafted polymer chains [29] relative to the sporadic nature of co-polymerized co-monomer [28]. [PERSON] _et al._ prepared generic poly(BuMA-_co_-EDMA) monolithic columns, to which zones of _m_-aminophenyl boronic acid were immobilized in two spatially discrete areas via poly(VAL) grafts [74]. The column was also subjected to the grafting of PEGMA in order to reduce non-specific binding [7] prior to VAL grafting and attachment of the boronate ligand. Using sC\({}^{4}\)D techniques, a study was performed into the pK\({}_{\text{a}}\) of immobilized boronate ligand following its immobilization using a range of pH buffers. Later, the group performed another investigation of pK\({}_{\text{a}}\) of aminocarbylates following immobilization on grafted VAL sites [75]. The pK\({}_{\text{a}}\) of the immobilized acids were shifted from those reported in the literature for bulk solutions. This work demonstrates that photo-grafting can be exploited for the investigation of the fundamental properties of immobilized functional groups. The use of UV initiating techniques is limited by the composition of monolithic column housing materials. For _in situ_ polymerizations, fused silica capillaries coated in Teflon (PTFE) are generally used for UV-initiated procedures, but diameters greater than 250 \(\upmu\)m are not widely available. Polyimide coated capillaries are widely available and cheaper than their PTFE counterparts. [PERSON] _et al._ used light at a wavelength of 470 nm to initiate the polymerization of poly(styrene-_co_-divinyl benzene) (poly(STY-_co_-DVB)) monolithic columns within PTFE coated capillaries [76]. Later, an in-houseprepared spiropyran monomer was grafted to the surface of poly(BuMA-_co_-EDMA) monolithic columns in polyimide coated capillaries using light initiation at 660 nm [77] (see Table 1). The use of chelate immobilized monolithic columns has so far been restricted to the ring opening reactions of GMA in GMA supported monoliths, but few rely on surface grafting [13, 52, 75]. [PERSON] _et al_. prepared poly(LMA-_co_-EDMA) monolithic columns with subsequent poly(VAL) grafts [78]. Chelating ligands, such as iminodiacetic acid (IDA) and acetyl-iminodiacetic acid, were immobilized via the poly(VAL) grafted chains. The resulting columns demonstrated efficiencies lower than 5,000 N/m, however, enhanced selectivity was evident. In a second report [79], [PERSON] _et al_. grafted poly(LMA-_co_-EDMA) monolithic columns with the epoxide containing a GMA monomer, which was subsequently used for IDA immobilization. The column was used in the separation of transition metals in seawater samples, however, the efficiency although improved from poly(VAL) grafts [79], was still relatively low, at 5,070 N/m.