Research On Applicability For The ICP-OES To Substitute For The National Standard To Detection These 8 Metallic Elements On Food

The K?Na?Ca?Mg?Fe?Mn?Cu?Zn are important for human physiology on food. Each of these projects are also made the corresponding national testing standards by national standards committee. But there are some disadvantages for the practical application in these national standard method. They can not satisfy the requirement of the test.Inductively Coupled Plasma Optical Emission Spectrometry(ICP-OES), is a new element detection spectrum instrument was invented in the 1960 s. It can be recovered some drawbacks of national standard method by the multielement determination at the same time and the wide linear range.In order to research on applicability for the ICP-OES substitute overall how to detection these 8 of metallic elements on food. Seeking a better method for modern detection. This study will do comparison test from pretreatment, accuracy,precision and so on. The main research and results are as follows:(1) Determined the best detection line and linearity range of these eight elements for ICP-OES, results are as follows:The best detection line of Ca?Cu?Fe?K?Mg?Mn?Na?Zn are: 317.933 nm?327.395 nm?238.204 nm?766.491 nm?285.213 nm?257.610 nm?588.995 nm?213.857 nm;The linearity range of Ca and Na is:1.00 mg/kg~100 mg/kg;The linearity range of Cu?Fe?Mn and Mg is 0.10mg/kg~100 mg/kg;The linearity range of K is:0.50 mg/kg~100 mg/kg;The linearity range of Zn is:0.10 mg/kg~20.0 mg/kg.Each element of the linear range is several times increase than the national standard method. Greatly reducing the dilution multiple or without dilution, reduce the error from dilution test and heavy human operation, Suitable for the determination of high content.(2) Determined the detection limit and quantitative limit of the nitric acid-wet digestion?mixed acid-wet digestion and dry-ashing, which are the most suitable for pretreatment methods.We found that the detection limit of these three pretreatment methods are all up to 10-9.They are all better than the national standard method significantly. Also can meet the requirements of these project. Results are as follows: dry–ashing < nitric acid-wet digestion < mixed acid-wet digestion.(3) Using 20 national standard material accuracy to test these three pretreatment methods respectively, results are as follows: the hit rate of nitric acid-wet digestion is 61.5 %?mixed acid-wet digestion is 59.6 %?dry–ashing is 46.8 %. The errors of wet digestion are all errors within 10.0 %. The wet digestion are all meet the testing requirements,but the dry–ashing only 70.0 %. Shows that wet processing can meet the detection requirements of these eight kinds of elements in most food.(4) Determine the appropriate acidity of the experimental solution for ICP-OES,results are as follows: nitric acid-wet digestion:K:2.0 %(V/V)?Na:4.0 %(V/V)?Ca:2.0 %(V/V)?Mg:2.0 %(V/V)?Fe:8.0 %(V/V)mixed acid-wet digestion shoule control in :K:4.0 %(V/V)?Na:4.0 %(V/V)?Ca:2.0 %(V/V)?Mg:4.0 %(V/V)?Fe:8.0 %(V/V)?Mn:8.0 %(V/V)?Cu:8.0 %(V/V)?Zn:4.0 %(V/V)?In order to ensure accuracy testing eight kinds of elements at the same time, the nitric acid concentration of medium and mixed acid concentration should be no higher than2.0 %(V/V).(5) The study found that the detection still can be ensured a good accuracy when contents between elements are up to 200 times difference,the errors are within10.0 %. Basically there is no interference between these projects, meet the testing requirements.(6) Selected 27 kinds of food samples to be the methods comparison and recovery experiment towards the wet digestion.It can be furthered proof the accuracy and practicability of the methods, results are as follows: 41.2 % of methods comparing data are error within 5.0 %, 37.6 % of methods comparing data are error in5.0 %~10.0 %,91.5 % of methods comparing data are error within 15.0 %.The standard addition recovery rate of nitric acid-wet digestion and mixed acid-wetdigestion are all between 90.0 % ~ 110 %, the result is satisfied.(7) At least, we text the method precision and long term precision by national standard material. Results show that all the projects can ensure RSD?10.0 % in 20 days, the result is satisfied.Final conclusion, We can be detection these eight kinds of elements in most of the food by ICP-OES at the same time. Compare of the national standard method,more efficient and accurate better testing parameters, testing more efficient, using more convenient, application field widely.It adapt to the requirement of food safety testing in the new period by the release of productivity and cost savings.