Preparation Of Bifunctional Molecularly Imprinted Polymers And Its Application In Food Pigment Analysis

The molecular imprinting polymer (MIP) was widely used for its predetermination, recognition and selectivity. The bifunctional molecularly imprinted polymer was more favorable to recognize the template than the monofunctional molecularly imprinted polymer. A novel bifunctional molecularly imprinted polymer was synthesized in this paper, and it was applied to the determination of dyes in food. The evaluation of validation data verified that the MIP has high selectivity and low detection limit, and it can be applied for determination of dyes in food. The study was divided into four sections.(1) Introduction. The principle, development and application of molecular imprinting technique and solid phase extraction, the current situation and detection method of dyes were summarized.(2) A novel bifunctional molecularly imprinted polymer was synthesized in aqueous system with congo red as template, Beta-Cyclodextrins-maleic anhydride (β-CD-MA) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) as co-functional monomers and N, N-methylenebisacryl amide (MBA) as cross-linking agent, respectively. MIP was used as selective sorbent for the solid-phase extraction (SPE) of congo red from food, and the elution was determined by HPLC. The mean recovery was 84.2-105.2%, the RSD≤ 1.2%, the repeatability was 1.1-3.8%. The LOD and LOQ were 0.07 and 0.23 μg Kg-1, respectively. The results showed that the MIP possessed the characteristic of high selectivity, low LOD and good repeatability, and a new analytical method of congo red in food was established.(3) Four different molecularly imprinted polymers were synthesized with tartrazine as template, acrylamide (AM), Beta-Cyclodextrins-maleic anhydride (β-CD-MA), [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC), Beta-Cyclodextrins-maleic anhydride (β-CD-MA) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) as functional monomers, respectively. The four MIPs were compared by adsorption and selectivity. The result showed that the bifunctional molecularly imprinted polymer possessed the characteristic of high adsorption capacity and selectivity compared with the monofunctional molecularly imprinted polymer, the synergistic effect of the two functional monomers made the performance of MIP more superior. The MIP was used as selective sorbent for the solid-phase extraction (SPE) and detected the tartrazine in food by HPLC, and the elution was determined by HPLC. The mean recovery was 89.4-106.2%, the RSD was 0.47-1.7%, the repeatability was 1.3-3.1%. The LOD and LOQ were 0.08 and 0.27 μg Kg-1, respectively.(4) A novel molecularly imprinted polymer was synthesized with carbon nano tube (CNT) employed as matrix, tartrazine as template, Beta-Cyclodextrins-maleic anhydride ((3-CD-MA) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) as co-functional monomers and N, N-methylenebisacryl amide (MBA) as cross-linking agent, respectively. The CNT-MIP didn’t change the adsorption capacity of the CNT, while greatly improved the selectivity of CNT. The new analytical method of CNT-MIP-HPLC was used to detect the tartrazine in food. The CNT-MIP was used as selective sorbent for the solid-phase extraction (SPE) of tartrazine from food. The mean recovery was 88.6-102.4%, the RSD was 0.95-4.6%, the repeatability was 0.86-2.62%. The LOD and LOQ were 8.33×10-5 ng L-1 and 2.78×10-5 ng L, respectively.