Optimization Of Testing Conditions Of Cr, Cd And Pb Content In Rice Using GFAAS By Response Surface Method

Rice is the most widely consumed staple food for most of the world's population,especially in China.However,due to the increasingly serious environmental pollution,there are also some heavy metals in the rice.Studies have shown that rice in China suffers from chromium,cadmium,etc.The pollution of heavy metals such as lead has been serious.Although these metals have extensive and important applications in the chemical industry and manufacturing industries,once they enter the human body through the food chain,because of their long half-lives,they are difficult to be degraded in the body and accumulated in a certain amount.It can cause serious damage to various organs such as lungs,kidneys and livers,and even lead to death.We need to determine the content of these heavy metals in rice strictly,thus the accuracy of the detection method is particularly important.At present,atomic absorption spectrometry(AAS)is the most commonly used method for the detection of heavy metal elements,which is based on the absorption of ground state atomic vapor on characteristic spectral lines.The multipurpose atomizer is graphite furnace and flame.It has the advantages of low detection limit,short analysis time,can be applied to analysis of various elements and strong anti-interference ability.Therefore,three kinds of heavy metal elements were detected by graphite furnace atomic absorption spectrometry,and the influencing factors were optimized.Microwave digestion method is selected for sample pretreatment because of its rapid reaction,simple operation and less reagent consumption.In this study,three main factors affecting the determination of heavy metals(chromium,cadmium,lead)by graphite furnace atomic absorption spectrometry were studied: acid content,ashing temperature and atomization temperature.The single factor test and response surface curve analysis are used to optimize the system.According to the optimization results and the actual conditions,the optimal measurement conditions are selected.The results show that the optimum reaction conditions are as follows: the volume of nitric acid is 6 mL,the ashing temperature is 900?,the atomization temperature is 2500 ?,the correlation coefficent can reach 0.9995 when drawing the standard curve,the precision is 0.55% and the standard recovery is 93.56%.The optimum reaction conditions are as follows: the volume of nitric acid is 6 mL,the ashing temperature is 200 ?,the atomization temperature is 1700 ?,the correlation coefficent can reach 0.9983 when drawing the standard curve,the precision is 1.50% and the standard recovery is101.11%.The optimum reaction conditions are as follows: the volume of nitric acid is 6 mL,the ashing temperature is 300 ?,the atomization temperature is 2000 ?,the correlation coefficent can reach 0.9999 when drawing the standard curve,the precision is 0.52% and the standard recovery is 107.69%.The above data show that the optimized conditions have good precision and reliability.At the same time,the results obtained under this optimum condition are compared with those of the national standard.At the same time,the results obtained under this optimal condition are compared with those obtained in the national standard.The results show that the precision of the three elements measured under the optimal conditions is higher than that measured under the national standard.That is to say,the accuracy of the measurement can be improved by using the optimized conditions of this test.The results show that this condition can be used to measure the heavy metals chromium,cadmium and lead in rice samples,in order to ensure food safety and provide a theoretical basis for the detection of other heavy metal elements.