Quinolinecarboxylic Acid-linked Covalent Organic Framework Microsphere for On-line Solid Phase Extraction of Four Aflatoxins
In this study,on-line solid phase extraction(SPE)based on quinolinecarboxylic acid-linked covalent organic framework(QCA-COF)microsphere was developed.On-line SPE coupled with high performance liquid chromatography(HPLC)was used for the determination of four aflatoxins(AFs)in food samples and Chinese medicinal herbs,including AFB1,AFB2,AFG1 and AFG2.QCA-COF microsphere was successfully synthesized via the Doebner multicomponent reaction.For this process,1,3,5-tris(4-aminophenyl)benzene,4,4'-biphenyldicarboxaldehyde and pyruvic acid were used as the synthetic monomer under the catalysis of sulfamic acid.QCA-COF microsphere was characterized by scanning electron microscope,Fourier transform infrared spectroscopy,pow-der X-ray diffraction,and N2 adsorption-desorption isotherms.The results showed that micro-sized QCA-COF microsphere was obtained in a solution of 1,4-dioxane-acetonitrile(1∶4,volume ra-tio).The structure of QCA-COF has aromatic rings,pyridine groups and—COOH groups,which permits multiple binding interactions with aflatoxins.Based on their binding groups,QCA-COF ex-hibited excellent on-line SPE capability compared to the commercial materials,such as C18,PSA and GCB.The extraction parameters of the adsorption and elution processes were optimized in detail,including flow rates of loading,eluting solvent,volume of eluting solvent,and flow rates of elution.The optimal conditions were shown as follows:loading flow rate,0.4 mL·min-1;eluting solvent,300 μL of 0.1％acetic acid in methanol;elution flow rate,0.2 mL·min-1.Under the optimized conditions,the developed on-line SPE coupled with HPLC method provided good recovery(82.5％-105％),good precision(4.3％-10％,n=6),and low limit of detection(0.024-0.030 ng·g-1).The intro-duced method was successfully used to analyze four AFs in peanuts,wheat,orange peel,almonds and cassia seed.
万方数据
维普
