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Development of Molecularly Imprinted Polymers for the Analysis of Amphenicols in Milk
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1  University of Santiago de Compostela

Abstract: Chloramphenicol (CAP) is a broad-spectrum bacteriostatic antibiotic commonly used in veterinary medicine and active against both Gram-positive and Gram-negative bacteria. However, toxic effects in humans such as Grey syndrome, bone narrow suppression, and fatal aplastic anaemia have been described. As a consequence, the use of CAP in foodstuffs has been banned within European Union (EU) since 1994 and no maximum residue limit (MRL) has been established in animal-derived foods. CAP belongs to the amphenicol family of antibacterial agents, that also includes thiamphenicol (TAP) and florphenicol (FLP), approved for use in all food-producing animals. For TAP and FF, maximum residue limits have been established in different matrices for all food producing species. Although LC–MS is the most widely used method for routine determination of amphenicols, in the analysis of real samples with complex matrices it usually implies previous clean-up steps using common solid-phase extraction (SPE) procedures. The main drawback of this extraction technique is the lack of selectivity of the sorbents which requires the optimisation of the extraction and clean-up of target analytes, including column conditioning, sample loading, washing and elution. Molecularly imprinted polymers (MIP) are synthetic materials with recognition sites that specifically bind target molecules in mixtures with other compounds. MIP sorbents, which imitate natural recognition, are capable of meeting the demands of SPE. The aim of the present work is to test the suitability of chloramphenicol for being used as template molecule in the design of molecularly imprinted polymers for amphenicol extraction. Precipitation polymerisation has been used and MIP were tested and optimized for the solid-phase extraction (MISPE) of the group of three, structurally related amphenicols. Recoveries were calculated using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The applicability of these polymers as sorbents for the extraction of amphenicols in milk has been tested.
Keywords: MIP, MISPE, milk, amphenicols,LC-MS/MS