[Rapid determination of trace ciprofloxacin residue in milk samples using molecularly imprinted membrane extraction-high performance liquid chromatography-tandem mass spectrometry]

An enrofloxacin (ENR) molecularly imprinted membrane (MIM) was prepared with a polyvinylidenedifluoride (PVDF) membrane as the carrier, ENR as the dummy template molecule, α-methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and a chloroform-methanol mixture solvent as the porogen. The MIM showed excellent selectivity, high adsorption capacity, and high adsorption rate for ciprofloxacin. Additionally, a method combining molecularly imprinted membrane extraction (MIME) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated for the selective analysis of trace ciprofloxacin residue in milk samples. The sample pretreatment involved only a single step of protein precipitation. Ciprofloxacin showed good linearity in mass concentration range of 0.1-200 μg/L with a high correlation coefficient (r²>0.9996). The limit of detection (LOD, S/N=3) and limit of quantification (LOQ, S/N=10) were 0.02 μg/L and 0.1 μg/L, respectively. The relative standard deviations (RSDs) of interday and intraday precisions ranged from 3.3% to 7.9%. The ciprofloxacin recovery was in the range of 92.6%-119.1%. The results showed that the proposed method is simple and fast, with high accuracy and sensitivity, thus being suitable for the rapid detection of trace ciprofloxacin residue in milk samples.