Determination Of Preservative And Phenoxyacetate Acid Compounds With Magnetic Solid-phase Extraction-High Performance Chromatography

In the work of chemical analyses,sample preparation is a critical and normal process.As a revolutionary technique invented in the 21 st century,magnetic solid-phase extraction(MSPE)has been received great attentions in the society.And the magnetic or magnetizable materials are used as the adsorbents in this new sample preparation technique.It has many desirable characterization,effective,quick,economic,and so on.In the last decate,MSPE received more attention in many fields,such as food science,environmental pollution and medical science.As the core of MSPE technique,the development and preparation of new adsorbents are critical to expand the application of this technique.In recent years,the development of novel MSPE adsorbents has been attracted more and more attention among the researchers.In this work,we introduced the amino-acid derivatives into the preparation of two kinds of MSPE adsorbents for the analysis of food preservative and plant growth regulators in food samples via free radical polymerization.And the adsorption properties were investigated.The detailed studies were as follows:1.poly(styrene-co-N-methacryloyl-L-phenylalanine methyl ester)-functionalized magnetic nanoparticles were constructed and used as magnetic solid-phase extraction adsorbents for analysis of food preservatives in beverages.To prepare the poly(amino acid)-based adsorbents,N-methacryloyl-L-phenylalanine methyl ester,and styrene served as the functional monomers and modified onto the magnetic nanoparticles via free radical polymerization.Interestingly,compared with propylparaben and potassium sorbate,the proposed poly(amino acid)-based adsorbents showed a good selectivity to sodium benzoate.The adsorption capacity of the adsorbents to sodium benzoate was 6.08 ± 0.31 mg/g.Moreover,the fast adsorption equilibrium could be reached within 5 min.Further,the resultant poly(amino acid)-based adsorbents were applied in the analysis of sodium benzoate in real beverage sample.2.a novel MSPE adsorbent has been developed for enriching two plant growth regulators,including 2,4-dichlorophenoxyacetic acid(2,4-D)and 4-chlorophenoxyacetic acid(4-CPA),in bean sprouts.For preparing the MSPE adsorbent,poly(N-methacryloyl-L-phenylalanine methyl ester(P(MA-L-Phe-OMe)),amino acid-based polymer,was modified onto themagnetic nanoparticles via “grafting to” method by free radical polymerization.The resultant P(MA-L-Phe-OMe)-functionalized magnetic nanoparticles were characterized by Fourier transform infrared(FT-IR)spectroscopy and elemental analysis.The adsorption amount of nanoparticles to 2,4-D and 4-CPA were 39.82 mg/g and 29.02 mg/g,respectively.Moreover,the prepared MSPE adsorbents showed good selectivity towards 2,4-D and 4-CPA due to the hydrophobic interactions and electrostatic forces between the target analytes and adsorbents.The results demonstrated that the proposed MSPE adsorbents have high affinity to the targets2,4-D and 4-CPA.Under the optimized conditions,the proposed materials were successfully applied to enrich 2,4-D and 4-CPA in bean sprouts samples.The recovery values of the bean sprouts solution spiked the targets were from 90.9% to 96.4% with the relative standard deviations of 2.3–3.9%.In this work,the amio-acid derivatives was firstly introduced into the preparation of MSPE adsorbents.The resultant adsorbents had multiple functional groups and good biocompatibility.Based on the results,the introduction of the amino-acid monomer into the adsorbents was feasible to analyze the compound in food sample.The proposed MSPE adsorbents could be expected to be good and alternative materials with further adjusting monomer compositions in the future.