Synthesis of a Molecularly Imprinted Polymer for Melamine Analysis in Milk by HPLC with Diode Array Detection

Abstract

Abbreviations:AIBN -azobisisobutyronitrile; CL -cross-linker; EDMA -ethylene glycol dimethacrylate; Kd -dissociation constant; MAA -methacrylic acid; MIDE -molecularly imprinted dispersive extraction; MIP -molecularly imprinted polymer; NIP -nonimprinted polymer; PVA -polyvinyl alcohol; Qmax -maximum binding concentration; Rrecovery; T -template. Keywords:Molecularly imprinted polymer (MIP), matrix effect, molecularly imprinted dispersive extraction coupled with high-performance liquid chromatography. 2 AbstractA molecularly imprinted polymer for melamine was prepared by suspension polymerization, using melamine as template, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linker.The optimal template/monomer and monomer/cross-linker ratios were obtained, being defined as 1/15 and 1/12, respectively. The template removal was performed by Soxhlet extraction with methanol containing 10% of acetic acid, in two cycles of 24 h each. Under optimal conditions the imprinted polymer was used as a dispersive extraction sorbent to extract melamine from different milk samples, before HPLC-DAD analysis.The validated method presented a limit of detection of 0.6 mg/kg. From the analysis of six different milks, melamine was detected in two of the considered samples in a maximum concentration of 9.3 ± 0.3 mg/kg.3

A Higher Affinity Melamine Binding Aptamer Mutant for More Sensitive Detection

“…For the instrumental method, they have advantages such as accuracy results, qualitative and quantitative analyses. The limit of detection (LOD) of these methods is about 0.0081 pg mL À 1 -0.6 μg mL À 1 for high performance liquid chromatography (HPLC) [6,7] , 0.006 μg mL À 1 for Gas Chromatography-Mass Spectrometry (GC-MS), [8] but the instrumental method is complicated, expensive and professional. With the rapid development of nanomaterials, a serious novel methods by using nanomaterials were established, including electrochem-ical method [9] with LOD of 2 pM-288 nM, [10,11] , localized surface plasmon resonance (LSPR) with LOD of 0.08 nM-158 nM, [12,13] , surface-enhanced raman scattering (SERS) with LOD of 1 pM-0.08 mM, [14,15] , but these methods haven't been standardized and commercialized.…”

Molecular Affinity Agents for Intrinsic Surface-Enhanced Raman Scattering (SERS) Sensors

“…These materials are termed molecularly imprinted polymers (MIP). MIPs are used to achieve antibody-like target recognition from a cheaper, more robust synthetic system (Figure A). , The K D reported for MIPs tend to be moderate (1 × 10 –6 to 1 × 10 –5 M), , though lower than antibodies (see above). Linear polymers can bear side groups for specific interactions, such as a pendant sugar to bind a lectin protein.…”

Development of ELISA-Like Fluorescence Assay for Melamine Detection Based on Magnetic Dummy Molecularly Imprinted Polymers

“…Since 2008, the Chinese government has forbidden the artificial addition of melamine to any food, and the temporary limitation of the volume of melamine in liquid milk is 0.05 mg/Kg. Analytical methods such as high-performance liquid chromatography (HPLC) [27], gas chromatography-mass spectrometry (GC-MS) [28], HPLC-MS/MS [29], surface-enhanced Raman scattering [30], electrochemical immunosensing [31], and enzyme-linked immunoassays (ELISA) [32] have been used for melamine determination. Although these analytical methods are highly sensitive, selective, and efficient, they are time consuming, expensive, and need sophisticated instruments and highly skilled personnel.…”