Preparation Of Boronate-affinity Solid Phase Extraction Adsorbent And Application In Food Analysis

The sample pretreatment process is a key step in the determination of target substances in complex foods.Solid phase extraction technology has become one of the most commonly used sample pretreatment methods due to its advantages such as high recovery,high enrichment multiples,and low consumption of organic solvents.Different types of solid phase extraction sorbents can selectively separate and extract different types of target compounds.Boron affinity is based on covalent bonding and coordination between substituted boric acid and cis-diols.The direct covalent force of the boronic acid group on the solid adsorbent and the cis-diol group of the target substance can be used.For the separation of substances such as sugars,catecholamines,nucleosides,glycoproteins and glycopeptides.In this paper,a new analytical method for boron affinity solid phase extraction will be established,and a series of boron affinity materials with good recognition performance,high stability and large specific surface area are prepared as solid phase extraction adsorbent.The new packing of the column is used in the pretreatment of complex food in order to achieve the purpose of simple,efficient and fast analysis of complex samples.The specific research content includes the following two parts:Firstly,a boron-affinity hollow solid phase extraction adsorbent was prepared.The adsorbent has the characteristics of a hollow structure,a polyhydrophilic polymer coating,and a boric acid-functionalized shell.The prepared adsorbent was used in combination with solid phase extraction and high performance liquid chromatography to analyze three isoflavones(daidzein,daidzein and genistin)in a soy milk sample.The sorbent was characterized by transmission electron microscopy,Fourier transform infrared spectroscopy,and thermogravimetric analysis.The solid-phase extraction conditions were optimized and the selectivity of the sorbent was studied.Under the optimal conditions,the detection limit of the three isoflavones of this method is 3.8-7.3 ?g/L.The spiked recovery of the actual sample is between 67.4-104.7%,and the relative standard deviation is less than 3.8%.This indicates that this method can selectively extract isoflavones from complex matrices.Secondly,preparation of a boron-affinity hollow tin dioxide-based fragment template molecularly imprinted solid phase extraction adsorbent.The hollow structure can effectively bind the target molecule and promote the removal of template molecules.It forms a thin layer of poly 2-aniline ethanol by self-polymerization to cover the surface of the boron affinity hollow tin dioxide-based adsorbent.Hydrophilicity and limited residual boric acid content to avoid non-specific binding.In order to prove the successful preparation of the adsorbent,seven different characterizations were performed,and the parameters affecting the imprinting conditions and the solid-phase extraction conditions were optimized respectively.Both selective and competitive adsorption experiments show that the material can specifically identify polyphenols.In this experiment,three polyphenols(catechin,chlorogenic acid,and caffeic acid)in tea and fruit juice samples were studied in combination with solid-phase extraction and high-performance liquid chromatography.The detection limit is 0.005-0.046 ?g/mL.The recovery rate is between 82.3-104.3%.