| With the rapid development of food industry and the continuous promotion of food safety consciousness,the proper use,timely regulation and rapid detection of the edible synthetic pigment has became an important link to ensure the safety of consumers.Therefore,it is urgently need to build a detection method with the advantage of accurate,simple,fast and easy to popularize,for a comprehensive monitor and timely test of the edible synthetic pigment in food.Common detection methods are often cumbersome operation,complex separation and matrix interference with other issues,it also can not be used widely.Humic acid,a green,natural and widespread active raw material with low price,is an important adsorptive material.Combined with UV spectrophotometry,it can be used to detect the tartrazine in the food with the advantages of simple operation,fast,accurate,and good separation.The main research contents are as follows:(1)According to the unique structure of humic acid molecular,the aminated humic acid was prepared with Mannich reaction,then nano SiO2 was used as dispersant to prepare two aminated humic acid-nanometre SiO2 composite material,which named HA-D-S and HA-T-S.The nitrogen content of the synthetic products was measured by element analysis.The optimum synthesis conditions of HA-D-S and HA-T-S were determined by single factor experiment,and the response surface methodology was used to optimize the conditions.Main functional groups were explored by infrared spectrum which used to infer the synthetic route of HA-D-S and HA-T-S.The structural change was determinated through scanning electron microscopy(SEM)and thermal stability of the products was charactered by thermogravimetric analysis(TGA).(2)The adsorption properties of HA-D-S and HA-T-S for tartrazine were studied,which showed that both of them have higher adsorption capacity.The optimum adsorption value of HA-D-S and HA-T-S were 595.8 mg/g and 612.4 mg/g,respectively,at pH = 3.0.The kinetic adsorption showed that the adsorption behavior of HA-D-S and HA-T-S were accorded with the second-order kinetics model which was chemical adsorption.Langmuir model were also fitted well,combined with thermodynamic parameters,it indicated that the adsorption behavior were endothermic and spontaneous and monolayer preferential adsorption.Static desorption experiment indicated that 3 mol/L HCl can be basically desorption of HA-D-S-tartrazine and HA-T-S-tartrazine,but it has a poor reuse effect.Under the dynamic condition,50 mL and 45 mL of stripping liquid were able to completely elution.Zeta potential instrument was used to measure the electrical behavior of solid particles.Highest values were appeared at pH = 3.0,which were good for adsorption of tartrazine.Changes on the surface structure of HA-D-S and HA-T-S were characterized and analyzed by FE-SEM.(3)A method which was based on HA-T-S column and spectrophotometry was established for the determination of tartrazine,and it can be applied in orange soda,solid Tang drink and jelly successfully.The results were compared and verified by HPLC,which indicated that the created method was effective and accurate.The method can be used to separate,concentrate and detect of tartrazine in food,which has the advantages of simple operation,good reproducibility,high precision and accuracy,and can meet the requirements of the analysis and detection of food samples. |
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