Preparation,Characterization And Property Study Of Sodium Ferric Gluconate Complex

AIM Sodium ferric gluconate complex(SFGC)was prepared from D-sodium gluconate and FeCl3.Through the optimization of the preparation process,structure characterization,properties and stability evaluation,to obtain a new SFGC which had the high iron content,high yield,little free iron,excellent physicochemical properties and good stability.It can provide an effective reference for its further clinical research and industrialization development.The establishment of electrochemical determination method of iron content,which can provide a convenient and fast method of the determination for the research of iron supplement.Methods1.The preparation of SFGCSFGC was prepared from D-sodium gluconate and FeCl3 using a simple synthesis method.The appropriate level ranges for four independent variables,mass ratio of FeCl3 to sodium gluconate,reaction time,temperature and starting pH,were determined by single factor experiments.Subsequently,these reaction conditions were optimized by central composite and response surface methodology through second-order polynomial regression.By monitoring the synthetic reaction of SFGC,to study the effect of pH value on the iron content and yield of product.Under controlled pH conditions,specific production rate,iron content and yield of SFGC were investigated to select the optimal reaction conditions.2.The characterization properties of SFGCThe structure of SFGC prepared by optimal conditions were characterized by scanning electron microscopy,ultraviolet-visible spectrophotometry,fourier transform infrared,X-ray diffraction analysis and differential scanning calorimetry.Particle size,Zeta potential,electrical conductivity and PDI of SFGC were investigated to verify whether the product has the characteristics of the chelated iron complex.3.The properties of SFGCQualitative experiments of SFGC prepared by optimal conditions were investigated,major in the physicochemical properties,hydrolysis,reduction,antioxidant activity and so on.4.The stability of SFGCThe stability of SFGC as raw material was studied,including in factors experiments(temperature,humidity,light)and acceleration experiment.Appearance,loss on drying,pH,solution clarity,free iron,iron content and so on were used as indicators to investigate the stability of SFGC.5.Quantitative determination of iron in SFGC by cyclic voltammetryTo establish a new method for the determination of SFGC by cyclic voltammetry,which can determine the free iron and total iron content of the complex and get an accurate,fast,convenient,time-saving and low costs' analysis method.Results1.The optimal reaction conditions were established as follows: mass ratio of FeCl3 to sodium gluconate,2.03:1;reaction time;2.95 h;starting pH 11;and reaction temperature,100?.The iron content of the complex experimentally obtained under these optimal conditions was 31.43%,and the result was stable.Comparative analysis revealed that the synthetic reaction of SFGC was a process involving complexation,separation and re-aggregation,pH value was found to have a significant impact on the iron content and yield of product.The maximum iron content of 29.9% and the maximum yield of 129.12% were obtained when the reaction proceeded for 2 h with pH controlled at 11.Meanwhile,a 58.77% reduction in the particle size of SFGC as well as a 33.33% decrease in reaction time was found compared to that without pH control.2.Characterization analysis showed that the product was a solid block structure,uniform distribution,the little free iron ion,and the degree of polymerization was relatively high.The complexation reaction between D-sodium gluconate and Fe3+ was not a simple adsorption action,the conformation of D-sodium gluconate was changed,and the SFGC had a high thermal stability.The iron core of complex was polymerized?-FeOOH structure,so the product had the characteristics of the chelated iron complex,but had poor crystallinity.3.The synthesized iron complex is odorless,tasteless and brown-black solid powder,but presents a clear red-brown solution once dissolving in water.However,it is not soluble in ethanol,methanol and so on organic reagents.The solution could show Tyndall effect hinting4.colloidal property.The sample solution was added dropwise to the potassium ferrocyanide and potassium thiocyanate solution,but it did not produce precipitation like ferric hydroxide colloid.The results indicated that free iron did not exist nor contaminate in the solution.The precipitate was not observed and always remained clear solution in a range of pH 5-13,and the SFGC had better capability of the dissolution and reduction and the bioavailability.Moreover,antioxidant activity of SFGC was evaluated by the IC50 against hydroxyl free radical,2,2-diphenyl-1-picryl-hydrazyl(DPPH)free radical,nitrite and lipid peroxidation,and their values were 3.65,8.09,3.01,1.90 mg/mL,respectively.4.The results of stability experiments showed that high humidity had greater impact on the stability of SFGC,but stability will not be affected significantly under high temperature and light conditions.So raw material should be dried at low temperature storage conditions and has the long-term stability.5.The SFGC sample was treated with 5 M hydrochloric acid solution for 5 min as the test solution.The optimal conditions were as follows: the pH value was adjusted to 3,the scan rate was 0.05 V/s,the accumulation potential was 0.4 V and the accumulation time was 3 min.The Fe3+ standard solution in the range of 0.01 to 0.04 M and the peak current were linear correlation,and the RSD was 0.75~1.65%.The results had higher stability and better repeatability,it can also be applied to the determination of other composite iron.ConclusionThe SFGC was studyed by preparation process optimization,structure characterization,qualitative experiments and so on,the product of a high iron content,high yield and little free iron was obtained.The complex had excellent stability,good reduction,great antioxidant activity and many other advantages.The research has practical value and industrialization development,which provides new ideas for the development of novel iron supplement agent.