Cyromazine imprinted polymers for selective stir bar sorptive extraction of melamine in animal feed and milk samples

Abstract

In this work, a molecularly imprinted polymer (MIP) coated stir bar was prepared using a self-designed polytetrafluoroethylene (PTFE) mold and in situ polymerization, with cyromazine as the dummy template for the target melamine. The prepared MIP coated stir bar presented a uniform and porous surface as well as good chemical stability and selectivity for melamine. Based on it, a method of MIP coated stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) was developed for the quantification of melamine in food samples. Significant factors affecting the extraction efficiency of melamine by MIP-SBSE, such as the extraction solvent and time, stirring rate, desorption solvent and time, were investigated thoroughly. Under the optimal conditions, the analytical performance of this method was evaluated. The detection limit of the developed method was 0.54 μg L(-1) for melamine with an enrichment factor of 42-fold and the relative standard deviation (RSD) of 6.1% (c = 5 μg L(-1), n = 7), and the linear range was 2-200 μg L(-1). The established method was applied for the determination of melamine in a variety of real samples including cat food, dog food, chicken feed A, chicken feed B and milk powder, and the recoveries for melamine in the spiked samples were in the range of 76.2-98.2%, 80.0-85.5%, 89.5-113%, 85.0-95.5% and 65.0-111%, respectively. The proposed method presented a good specific recognition ability and matrix interference resistance, and was demonstrated to be effective and sensitive for the analysis of melamine in animal food and milk samples.

Recent trends in sorption‐based sample preparation and liquid chromatography techniques for food analysis

“…In this context, articles published in the last three years report some applications of SBSE in food analysis. It can be observed a tendency for SBSE analysis of solid samples such as: fruits, seeds, vegetables, animal feed, fish, and meat . Besides that, must be highlighted the use of these new coatings mentioned above in the works cited in this review.…”

Molecularly Imprinted Polymers

“…MIPs have been employed in numerous applications apart from sensing. These applications include targeted drug delivery, − in some ways the opposite of drug sensing, chromatographic separations of related molecules and food adulterants, − …”

Nanoporous Supramolecular Liquid Crystal Polymeric Material for Specific and Selective Uptake of Melamine

“…A great deal of research about melamine was focused on the melamine detection, since the protein determination method (the Kjeldahl method) was exploited to measure a falsely high protein concentration through the illegal addition of melamine, , whereas the separation methods of melamine have been barely studied. The current known extraction techniques including solid phase extraction (SPE) and molecular imprinted polymers (MIPs) are restricted by the poor selectivity and complex time-consuming process of SPE and low rebinding capacity in MIPs, respectively. − …”