Use of spectral mapping technique for the separation of solvent strength and selectivity on β-cyclodextrin polymer-coated HPLC column using monoamine oxidase inhibitory drugs as solutes

Synthesis of creatinine-imprinted poly(β-cyclodextrin) for the specific binding of creatinine

An artificial receptor for creatinine was synthesized by the method of molecularly imprinted polymer (MIP). beta-Cyclodextrin was used as a monomer cross-linked with epichlorohydrin in the presence of creatinine, which was a template for the imprinting. Different molar ratios of monomer to template were used to synthesize the polymers so that better specific adsorption ability towards creatinine could be achieved. The results showed that to carry out the polymerization with a molar ratio of monomer to template of 3:2 and monomer to cross-linking agent of 1:10 was proper. N-hydroxysuccinimide and 2-pyrrolinidone were used as the analogues of creatinine in the adsorption experiments of multi-component solutions to reveal the specific recognition ability of the molecularly imprinted poly(beta-cyclodextrin) (poly(beta-CD)) for the template molecule, creatinine. One such detection interference of creatinine was creatine, which also co-exists in serum. Hence, adsorption experiments of creatinine/creatine binary mixture were also carried out to investigate and confirm the specific binding of the creatinine-imprinted poly(beta-cyclodextrin) towards creatinine. The hydroxyl groups of the imprinted poly(beta-CD) was further capped by chlorotrimethylsilane (CTMS) to investigate the interaction between creatinine and the imprinted poly(beta-CD). The adsorption resulting from the mixture solution by MIPs suggested that the creatinine-imprinted poly(beta-CD) demonstrated superior binding effect for the target molecule, creatinine, rather than creatine, N-hydroxysuccinimide and 2-pyrrolinidone.

Solvent strength and selectivity on a porous graphitized carbon column separated by a spectral mapping technique using barbiturates as solutes

A spectral mapping technique (SPM) was employed for separating the strength and selectivity of the retention of 41 barbituric acid derivatives and 5 organic modifiers on a porous graphitized carbon column (PGC). The potency values calculated by SPM were considered to be indicators of the capacity of drugs to bind to the surface of PGC and the capacity of organic modifiers to remove the drugs from the surface. The dimensionality of the multidimensional selectivity maps was reduced to two by a nonlinear mapping technique. Calculations indicated that molecular lipophilicity plays a negligible role in the strength and selectivity of retention, proving that the retention mechanism of PGC deviates from those of traditional reversed-phase stationary phases. Sterical and electronic parameters exerted the highest influence on the retention, emphasizing the importance of the polar interaction and the sterical correspondence between the surface of PGC and the solute molecules.