The Development Of Electrochemistry Sensor Methods For Fast Detection Of Cadmium In Food

Cadmium is a non-essential element of the human body, but due to the large amount of waste pollution of the environment, cadmium can enter the body through the food chain accumulation and cause poisoning. Large-scale outbreak event of the "poisonous rice" from 2011 to 2012 sounded the alarm in our ears. Therefore it is imminent to establish and improve the detection technology of cadmium residues in food for monitoring heavy metal pollution remediation.At present, the conventional methods for detecting cadmium in food are mainly AAS, HPLC, ICP-MS, etc. All these methods are manipulatingcomplicated, time-consuming, high-cost, which makes it very difficult to be applied. So the electrochemical sensing method emerges as the times require with its advantages such as efficient, high sensitivity, high accuracy.Two kinds of cadmium detection method have been established in this paper. The related performances have been tested, and the methods have been evaluated as well. The research process and results are summarized as following: 1. Development of electrochemical sensor based on 8-hydroxyquinoline-modified glass carbon electrode:A new method based on 8-hydroxyquinoline-modified glass carbon electrode(GCE) was established for rapid detection of Cadmium(Cd2+). The electrochemical behavior of Cd2+ on modified GCE was recorded using differential pulse stripping voltammetry. The results showed that the 8-hydroxyquinoline-modified glass carbon electrode had good stability and sensitivity. The equation of this method was ICd =-7.488×10-7-7.983×10-6 C(mg/L), R2 =0.9929, SD=1.9634 ×10-7. A linear response of stripping peak current was displayed to the concentration of Cadmium in the scope from 0.05mg/L to 1mg/L, with the detection limitation of 50?g/L. The recovery rate of the method was more than 95%, and the accuracy rate was up to 95%. The detection time was less than 6 minutes, which was useful for fast detection of heavy metals in food. The detection method based on stripping voltammetry was easy to manipulate, and the result could be gotten within 6 minutes, which would provide a new detection method for Cadmium. The method is fast and efficient, which has laid a good theoretical and experimental basis for the rapid detection of heavy metals. 2. Development of electrochemical sensor based on Diphenylthiocarbazone-modified glass carbon electrode.The same method was used to modify the glass carbon electrode. The electrochemical behavior of Cd2+ on modified GCE was recorded using DPSV. The results showed that the Diphenylthiocarbazone-modified glass carbon electrode had good stability and sensitivity. The equation of this method was ICd=-8.152×10-7-2.841×10-5C(mg/L), R2=0.9977, SD =1.3066 × 10-7. A linear response of stripping peak current was displayed to the concentration of Cadmium in the scope from 0.02 mg/L to 1mg/L, with the detection limitation of 10?g/L. The recovery rate was more than 95%, and the accuracy rate was up to 95%. The test results are reliable, fast and less effected by other metals.In summary, sensing method by modified glassy carbon electrode has the advantages of simple operation, high sensitivity, and high specificity. In the future, the relevant parameters can be explored to improve the method applying, and the method can provide technical support for the detection of heavy metal residues in food.