Study On Detection Methods Of Multiple Heavy Metals In High-salt Foods

There are relatively mature standard methods for the determination of heavy metals in conventional foods,involving digestion of the sample and detection by atomic absorption spectrophotometry(AAS),atomic fluorescence spectrometry(AFS),inductively coupled plasma-atomic emission spectrometry(ICP-AES)or inductively coupled plasma-mass spectrometry(ICP-MS).However,for foods with high salt contents,such as soy sauce,pickles,etc.,there are no specific detection standard methods.The determination of heavy metalssuch aslead and cadmium in high-salt foods is of great significance for controlling toxic and harmful elements in high-salt foods and protecting the health of Chinese consumers.In this thesis,high-salt foods such as soy sauce,mustard,marinated pork,kelp,salty drinks and edible salt were studied.Traditional microwave digestion,dry digestion and wet digestion were used to digest the samples and ICP-AES was used to detect heavy metal elements,but the recovery rates of most heavy metal elements were less than 80%..By comparison,if an extraction procedure was added after digestion and before detection,the recoveries of lead,cadmium,cobalt,copper,antimony,tin,iron,nickel,zinc and antimony in high-salt foods were all above 80%.In the process of digestion of high-salt foods,microwave digestion,dry digestion and wet digestion were compared.The chelating agent and extractant were selected during the extraction process,and the acidity of the solution during chelation,the amount of chelating agent(2% APDC)and the amount of extraction solvent(chloroform)were optimized.The parameters for plasma emission spectrometer detection were optimized.Under the optimized condition,a method was established for the determination of heavy metals such as lead,nickel,cadmium,cobalt,antimony,zinc,tin,copper,iron and strontium in high-salt foods such as soy sauce,mustard,marinated pork,kelp,salty drinks and table salt.The conclusion of the experiment is as follows: the best pretreatment of high-salt food is microwave digestion,APDC is used as chelating agent and chloroform is used as extractant;when the p H of the chelating solution is 2.5,2m L of 2% APDC is added and 40 m L of trichloromethane(20 m L per time)is added,detected by ICP-AES with a linear range of 0.02-5 ?g/m L,cadmium,cobalt,copper,tin.The detection limits of iron,nickel and zinc are less than 0.1mg/kg.When the standard amount is more than 0.5mg/kg,lead,cadmium,etc.in high-salt foods such as soy sauce,pickles,cured meat,kelp,salt soda and edible salt.The recoveries of cobalt,copper,antimony,tin,iron,nickel,zinc and antimony are all greater than 90%,which is more conducive to the determination of heavy metal content in high-salt foods.The method has the advantages of high detection sensitivity,short time,high efficiency,good reproducibility and accurate quantification,and can meet the needs of determination of heavy metals in high-salt foods.