Influence of salt ions on binding to molecularly imprinted polymers
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Salt ions were found to have an influence on template binding to two model molecularly imprinted polymers (MIPs), targeted to penicillin G and propranolol, respectively, in water–acetonitrile mixtures. Water was detrimental to rebinding of penicillin G whereas propranolol bound in the entire water–acetonitrile range tested. In 100% aqueous solution, 3-M salt solutions augmented the binding of both templates. The effects followed the Hofmeister series with kosmotropic ions promoting the largest increase. Binding was mainly of a non-specific nature under these conditions. In acetonitrile containing low amounts of water, the specific binding to the MIPs increased with the addition of salts. Binding of penicillin G followed the Hofmeister series while an ion-exchange mechanism was observed for propranolol. The results suggest that hydration of kosmotropic ions reduces the water activity in water-poor media providing a stabilizing effect on water-sensitive MIP–template interactions. The effects were utilized to develop a procedure for molecularly imprinted solid-phase extraction (MISPE) of penicillin G from milk with a recovery of 87%.
KeywordsHofmeister effect Molecular imprinting Molecular recognition Penicillin G Propranolol Solid-phase extraction
This work was supported by the Swedish Research Council and the Swedish Foundation for Strategic Research (INGVAR, Individual Grant for the Advancement of Research Leaders).
- 32.EEC Council Regulation No. 2377/90 of 26 June 1990 laying down a Community procedure for the establishment of maximum residue limits of veterinary medicinal products in foodstuffs of animal origin (1990) Off J Eur Comm L224:1–8Google Scholar