The Study On The Determination Of Cadmium,lead,chromium And Nickel In Food By Coprecipitation-flame Atomic Absorption Spectrometry

The impact of heavy metals on human body is slow and long-term.Once it enters the human body,it is difficult to excrete with the metabolism of the body.Heavy metals may have a negative impact on human health,whether it is high or low concentration.The potential way for humans to be exposed to heavy metals is food intake.Therefore,it is very important to measure heavy metals in food with high accuracy and high precision.In this study,a new method to determine the content of Pb(II),Cr(III),Cd(II)and Ni(II)in food was established.The method is based on Cu(II)-DPC and Zn(II)-DPC as the co-precipitation carrier,and flame atomic absorption spectrometry as the measurement method.The coprecipitation conditions for each method such as p H,reagent dosage,co-precipitation time and centrifugation time,coexisting ions and enrichment factor were examined.Pb(II),Cr(III),Cd(II)and Ni(II)in the model solutions are quantitatively enriched,within the allowable range of error.The detection limits were found to be as 7.50?g/L Pb(II),0.35?g/L Cr(III),0.32?g/L Cd(II)and 0.78?g/L Ni(II)and the maximum preconcentration factor is up to 100.The relative standard deviation was found to be as 2.26%Pb(II),0.96%Cr(III),2.17%Cd(II)and 0.98%Ni(II).At the same time,the accuracy of the method was verified.The established method was used to determine the samples of peanuts,melon seeds,onions and peppercorns.In addition,this article explores the co-precipitation mechanism of each system to provide theoretical support for the choice of co-precipitation conditions.