Research Of Environmental-Frendly And Multiple Sensitive Sensor Rapidly Detecting Of Heavy Metals In Food

With the constant process of the society, the requirements of people’s life are higher and higher. Heavy metal is one of the important factors caulsing food safety problems. Because of its enrichment, persistence, biodegradability and toxicity, it constitutes a threat to environment and humanbeings.Heavy metal in food mainly comes from water, soil, air, and the enrichment of food chain. In addition, it can also be derived from the process of food processing, storage, transportation and sales. With the enrichment of heavy metal, it can be concentrated to tens of thousands times, then it affects people’s health after a certain time. So it becomes one of the main factors affecting the health of humans and animals.There are atomic absorption spectrometry, liquid chromatography and electrochemical methods for heavy metal detection methods. Electrochemical method has been at home and abroad as the standard detection methods, because it is economical, fast and easy operating,but its sensitivity, stability, accuracy and security still need to be improved.In this regard, on the basis of existing research studies this study have done following improvements:1. Summary of the main source, hazards and pollution status of heave metal pollution in food, and introduct commonly used detection methods, electrode materials electrochemical detection methods and their research progress.2.Research of multiple sensitive sensor CHA/[BMIM]PF6/SDBS/Nafion SPCE for rapidly detecting of trace lead in food:using carbonated hydroxyapatite, SDBS, Nafion and [BMIM]PF6to modify screen-printed carbon electrode to detecting trace lead. At optimizing detecting conditions,The signal peaks of square-wave stripping voltammetry have a linear relationship with the concentration of Pb2+in range from3μg/L to600μg/L, with detection limit of0.37μg/L (S/N)=3, the relative standard deviation (RSD) of the sensor was3.4%(n=8). The result determined by this method was similar to ICP-MS method. The result of interfering experiment is1000times of Na+, NH4+, K+and Ca2+can’t effect the signal of Pb2+, but20times of Cu2+and50times of Cd2+can reduce the signal of Pb2+. Thus, using CHA/[BMIM]PF6/SDBS/Nafion SPCE square wave stripping voltammetry detecting trace lead is a sensitive, environmental frendly, stable and economical method.3. Research of CHA/[BMIM]PF6/SDBS/Nafion SPCE sensor and I-for rapidly detecting of trace cadmium in fishmeal:using carbonated hydroxyapatite, SDBS, Nafion and [BMIM]PF6to modify screen-printed carbon electrode, adding iodide ion in the electrolyte so that the detection signal is further increased, and the peak shape can be better. At optimizing detecting conditions, The signal peaks of square-wave stripping voltammetry have a linear relationship with the concentration of Cd2+in range from10μg/L to300μg/L, with detection limit of0.46μg/L (S/N)=3, the relative standard deviation (RSD) of the sensor was6.2%(n=10). The linear regression equation is y=0.02524x+0.60924(R2=0.994), y is the current intensity, x is the concentration of Cd2+. The result determined by this method was similar to ICP-MS method.4.Compare the electrochemical effect between CHA and HAP:for the sake of studying a better sensor to detect Pb2+, Cd2+, Cu2+, this study use CHA and HAP to make CHA/[BMIM]PF6/SDBS/Nafion SPCE and HAP/[BMIM]PF6/SDBS/Nafion SPCE, with the method of square-wave stripping voltammetry to detect100μg/L Pb2+, Cd2+, Cu2+. Then compare the current intensity, stablity and linear rangement between them. The result is:CHA’s current intensity is greater than HAP’s; CHA’s stability is a little better than HAP’s; CHA has a wider linear rangement with Pb2+and Cu2+, while HAP has a wider linear rangement with Cd2+. Overall, CHA’s sensitivity and stability are better than HAP.5.A preliminary study of CHA/[BMIM]PF6/SDBS/Nafion SPCE simultaneosly detecting Pb2+, Cd2+, Cu2+and Zn2+:On the basis of the aforementioned studies, this study using CHA/[BMIM] PF6/SDBS/Nafion SPCE to detect lead, cadmium, copper and zinc, found that the peaks of four metals can be completely separated, and the signal peaks have a linear relationship with the concentration of Pb2+, Cd2+, Cu2+and Zn2+within a certain range. Optimizing detecting conditions:electrolyte solution is0.1mol/L pH5.0NaAc-HAc; Concentration of CHA is5mg/mL; deposition potential is-1.1V; deposition time is210s. Becuase CHA prioritly enrich Pb2+and Cu2+, there are certain requirements to the concentrations of Cd2+and Zn2+. If the concentrations of Cd2+and Zn2+are not high enough, there are no signal.6.Establishing relations between mini-DPSA-1-SPCE’s detecting values and concentrations of Pb2+in green tea:to simplify the process of the DPSA-1-SPCE detection of Pb2+in green tea, this study tries to establishing relations between detecting values(dt/dE) and concentrations of Pb2+. Detecting5samples of green tea, each sample detect20times,5samples have been totally detected for100times. Then linear fit the100values with the concentrations of Pb2+which are detected by ICP-MS. The linear regression equation is y=62.87821x+88.9789(R2=0.9904), y is the detected values(dt/dE), x is the concentration of Pb2+. The detecting results of actual samples:the relative standard deviations do not exceed7%, the relative deviations do not exceed15%. So this method is hopefully be used as a screening method, but its accuracy is still need to be improved.7.Conducting a summary and outlook to this study.