Development and Evaluation of a Molecularly Imprinted Polymer for the Detection and Cleanup of Benzylpenicillin in Milk

A molecularly imprinted polymer (MIP) was designed for benzylpenicillin via suspension polymerization. The specific absorption of benzylpenicillin to the MIP, applied in a molecularly imprinted solid-phase extraction (MISPE), was compared to the nonspecific binding using a NIP (nonimprinted polymer without a target molecule) in a non-molecularly imprinted solid-phase extraction. This validation was performed successfully in acetonitrile solutions and milk extracts spiked with benzylpenicillin. Significant differences in absorption were observed. In acetonitrile, the recoveries using MISPE (90-95%) were a fraction higher than those in milk extracts (70-80%). The validation revealed the limit of detection and the limit of quantitation for the MISPE application in milk samples to be 0.51 and 1.02 mu g/kg, respectively. In addition, comparing the results of the analysis of positive milk samples using MISPE with those using a classic sample preparation step showed a Pearson correlation of 0.989. Finally, cross reactivity tests using other antibiotics showed a certain cross reactivity, but non-beta-lactams were barely bound.