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Abstract: In this work, a simple and selective method based on matrix solid phase dispersion (MSPD) using molecularly imprinted polymers (MIPs) as sorbents was successfully developed for the determination of melamine (MEL) in milk powder. The MIPs have been prepared by surface imprinted polymerization method using carbon nanotube (CNT) as support, MEL as template molecule, γ-aminopropyltriethoxysilane as functional monomer, and tetraethyl orthosilicate as cross-linking agent. The MIPs were characterized by Fourier transform infrared spectrometer and scanning electron microscopy. At the same time, the adsorption isotherm, dynamic adsorption, and selective adsorption of MIPs to MEL were also studied. The prepared MIPs were used as dispersant of MSPD to extraction and separate MEL in milk powder. We optimized the extraction conditions as follows: the ratio of MIPs to sample was 2:3; the dispersion time was 10 min; washing solvent was 2.0 mL acetonitrile; and elution solvent was 4.0 mL ammonium methanol (5:95, v/v). Once the MSPD process was completed, the MEL extracted from milk powder was determined by LC-MS/MS. Under the optimal conditions, the limit of detection of MEL was 0.2 ng g-1. The relative standard deviations of intra-day and inter-day were obtained in the range of 0.4~5.1 %. The satisfied recoveries of MEL were 92.5~97.2 %. The MIP-MSPD method has some advantages, such as higher selectivity, lower cost of preparation, less time consuming and organic solvent consumption, simpler sample pretreatment procedure, and higher extraction recovery compared with those existing methods which were used for determination of MEL
Template and target information: melamine, MEL
Author keywords: Carbon nanotube, Molecularly imprinted polymers, Matrix solid phase dispersion, Melamine, LC-MS, MS