TOWARDS A MISPE FOR ROXARSONE: IMPRINTED POLYMERS BASED ON TAILOR-MADE MONOMERS FOR THE RECOGNITION OF ORGANO-ARSENIC COMPOUNDS
2School of Chemistry and Chemical Engineering, Queen’s University, Belfast
Roxarsone (4-hydroxy-3-nitrophenylarsonic acid) is an organo-arsenical feed additive for swine and poultry, which promotes weight and serves as an anti-microbial agent. Although the use of arsenic‐containing feed additive can promote the development of animal husbandry, concerns have been raised on the presence of arsenical residua in animal husbandry-derived foods for human nutrition. Moreover, livestock excreta containing organic arsenic compounds can be discharged in the environment, causing further pollution issues.
With the aim of developing a molecularly imprinted solid phase extraction selective for roxarsone, we prepared stoichiometrically imprinted polymers against this target contaminant.
Five different MIPs were synthesized using tailor-made functional monomers, based on urea or squaramide structures as molecular recognition elements, with the goal to bind stoichiometrically roxarsone in polar environments. Prepolymerisation studies of template–monomer complexation by 1H-NMR experiments showed that squaramide monomers give Kaff values higher than ureas, even if both kinds of monomers could generate MIPs with good binding properties toward roxarsone.
After the synthesis of imprinted polymers, equilibrium rebinding experiments performed in environments of different polarity showed that roxarsone is well recognized in water, while methanol and less polar solvents showed no significant differences between MIP and NIP. Moreover, the imprinted polymer showed a fair selectivity towards possible interfering substances like acetarsone (N-acetyl-4-hydroxy-m-arsanilic acid) and nitarsone (4-nitrobenzenearsonic acid). Preliminary results on the feasibility of a MISPE for roxarsone in aqueous matrix will be presented
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