Determination Of Sodium Nitrite In Milk By Electrochemical Sensor Based On Carbon Fiber Cloth Electrode

With the development of scientific progress,nitrates and nitrites have recently become hot spots in medicine and physiology,and people’s understanding of sodium nitrite is becoming more and more comprehensive.The view of nitrite can help the cardiovascular system of people is more and more convincing.However,the unchanging principle is that the moon waxes only to wane and water brims only to overflow.The material entering the body should be in the appropriate dosage.It will be harmful to the human body when the amount of nitrite exceed proper dosage.Sodium nitrite is a kind of common food additives,which as a general preservative and color fixative of meat products.The contents of nitrite of preserved meat and pickled vegetables are higher.When people ingest too much sodium nitrite,it can cause acute poisoning to human body organization distortion and developing cancer.In order to ensure food safety,the detection methods for sodium nitrite have been proposed.With the increase of per capita income in our country,people’s living standard especially for the daily consumption of milk has been greatly improved.But testing method of sodium nitrite in milk didn’t get effective improvement and breakthrough.To solve this problem,two kinds of electrochemical sensors are constructed in this paper for detection sodium nitrite in milk.The research contents are as follows:（1）Fabrication of carbon fiber cloth（CFC）based electrochemical sensor for sodium nitrite detection in milk.In this method,the detection limit of sodium nitrite is 4.75μM,and the time of oxidation current achieving steady state is around 7 s.There is a good linear relationship between current density and the concentration of sodium nitrite in the range of4.75μM and 3.8347 m M.Corresponding linear regression equations are:y(m M cm^-2)=1.5471 x+0.001279,R²=0.9981;y(m M cm^-2)=0.9977 x+0.7887,R²=0.9934.（2）In order to improve the performance of carbon fiber cloth,nitric acid was used to treat carbon fiber cloth to etch its surface which can expand the surface contact area to increase the conductivity and improve the detection performance of sodium nitrite.This modified CFC has a smaller determination limit of 0.7μM and time of steady-state oxidation current of 5 s compared with CFC.There is a good linear relationship between current density and the concentration of sodium nitrite in the range of 0.7μM and 3.8352 m M.Corresponding linear regression equation is:y(m M cm^-2)=1.1012 x+0.0004,R²=0.9989.The stability,interference and actual sample testing show that the modified CFC electrode has excellent performance in the detection of sodium nitrite.