The Study On Determination Of Cu,Cd And Cr In Food Samples By Cloud Point Extraction And Enrichment-Flame Atomic Absorpition Spectrometry

As people pay more and more attention to environmental pollution and public health,the analysis of heavy metals has become one of the important topics in the field of analytical chemistry.Heavy metal pollution usually exists in water,soil and air from natural and man-made sources.Specifically,pollutants formed in aquifers are an important source to be monitored.Therefore,it is necessary to determine the content of heavy metals in food samples.Flame atomic absorption spectrometry has the advantages of cost-effectiveness,easy operation and accurate determination,which is widely used in the determination of metal ions,but for flame atomic absorption spectrometry,the atomization efficiency of the sample to the flame is low,and the analyte atoms from the hollow cathode lamp will quickly withdraw from the light path,so the detection limit of the analyte is higher.Therefore,it is necessary to adopt separation and enrichment technology to further improve the detection limit and sensitivity of the instrument.Cloud point extraction?CPE?is a green,rapid,efficient,simple and low-cost enrichment and separation method,which is widely used in trace metal analysis,environmental pollutants,drug analysis and other fields.In this paper,2-mercaptobenzothiazole?MBT?was used as complexing agent and TritonX-114 as surfactant,cationic surfactants cetylpyridinium chloride?CPC?,cetylpyridinium bromide?CPB?and octadecyl dimethyl benzyl ammonium chloride?BDMSAC?were used to form ternary complexes with metal ions to be determined,and then flame atomic absorption spectrometry was used to determine trace copper,cadmium and chromium in food samples.The influencing parameters such as pH value,complexing agent,Nonionic surfactant,ionic strength,temperature of water bath and ice bath,centrifugation time,diluent and coexisting ions were optimized in detail.the detection limit,sensitivity and precision of the method were discussed.In this paper,three systems were studied based on the technology of cloud point extraction,separation and enrichment:1.Cu-MBT-CPC cloud point extraction for the determination of Cu,in adzuki bean showed that the sensitivity of this method was 0.21?mg/L?^-1,the precision was0.45%,and the detection limit was 0.074?g/L.2.Cd-MBT-CPB cloud point extraction for the determination of Cd,in shrimp meat showed that the sensitivity of this method was 0.34?mg/L?^-1,the precision was0.24%,and the detection limit was 0.051?g/L.3.Cr-MBT-BDMSAC cloud point extraction for the determination of total Cr,in apples shows that the sensitivity of this method is 0.17?mg/L?^-1,the precision is0.37%,and the detection limit is 0.69?g/L.