An in situ immobilized pipette tip solid phase microextraction method based on molecularly imprinted polymer monolith for the selective determination of difenoconazole in tap water and grape juice

A pipette tip-based molecularly imprinted polymer monolith microextraction (PT–MIPMME) method was developed for the selective extraction of difenoconazole in tap water and grape juice. In this method, molecularly imprinted polymer (MIP) monolith used as the sorbent was synthesized at the tip of a micropipette. This in situ polymerization reaction used difenoconazole as the template and methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and the mixture of toluene–dodecanol as the porogenic solvent. The pipette tip containing MIP monolith was matched to a syringe for performing the polymer monolith microextraction (PMME). Several parameters affecting the proposed PT–MIPMME method were investigated, including the flow rate, sample volume, pH and salt concentration of sample, the type and volume of eluent. Under the optimal conditions, the PT–MIPMME method showed a low limit of detection of 0.5 μg L−1. The recoveries were in the range of 87.6–95.4% with relative standard deviations less than 4.9%. The results showed that difenoconazole was selectively enriched from tap water and grape juice samples.