Study On The Distribution And Transformation Regularity Of Chromium And Its Speciation In Marine Products

Marine product has become the preferred high-quality food because of its delicious taste and rich in nutrients such as high protein.However,the particular habit of marine product leads to its high concentration of heavy metals.Chromium is a non-biodegradable heavy metal that can be persistently accumulated in marine product.Chromium exists primarily in the forms of trivalent chromium(Cr(?))and hexavalent chromium(Cr(?))in natural environment.The former is an essential micronutrient for human body,while the latter is highly toxic and carcinogenic.Therefore,the determination of total Cr can no longer characterize its harmfulness,it is necessary to carry out the speciation analysis of chromium in order to evaluate the pollution situation of chromium element scientifically and reasonably.In this paper,the content of Cr in marine products along the coast of Zhejiang Province was determined by inductively coupled plasma mass spectrometry(ICP-MS),and its distribution characteristics were studied and the health risks of consumption were evaluated.A method for simultaneous quantitative analysis of Cr(?)and Cr(?)in marine product by high performance liquid chromatography inductively coupled plasma mass spectrometry(HPLC-ICP-MS)was established and the distribution characteristics of chromium speciation were analyzed.The transformation of Cr(?)in Mytilus coruscus was studied by using Cr(?)reference material as poisoning reagent.The main contents and results are as follows1.ICP-MS was used to quantitatively analyze the content of Cr in 21 species of typical marine products collected from the coast sea of Zhejiang Province.In this study,the distribution of Cr in marine products was analyzed based on the results of sample testing.Single factor pollution index method(Pi)was used for the monitoring results to evaluate the pollution degree of Cr in different marine products Meanwhile,combined with the dietary data from The Fifth China Total Diet Study,the non-carcinogenic risk assessment method was used to calculate the target hazard quotients(THQs)of Cr.The results showed the Pi value of shellfish was 0.83,which belonged to moderate pollution The Pi values of shrimp and crab were 0.25 and 0.28,which were at a light pollution level;The Pi value of fish was 0.16,which was uncontaminated.The THQs of the four types aquatic products were 0.012-0.070,which were less than the safety reference value 1.The above results indicated that there were no potential health risks to human body if they consumed this marine product.2.The HPLC-ICP-MS method was established to simultaneous analysis Cr(?)and Cr(?)in marine product,and the distribution characteristics of chromium speciation in marine products along Zhejiang coast were analyzed.Accordmg to the characteristics of chromium and actual samples,the chromatographic,mass spectrometric conditions and extraction methods were optimized,then Cr(?)and Cr(?)were separated in 2 minutes.The correlation coefficients of Cr(?)and Cr(?)in the linear range of 0.1-20.0 ?g/L all reached 0.9999.The detection limits of Cr(?)and Cr(?)were 0.034 ?g/L and 0.049 ?g/L respectively,and the quantitative limits were 0.10 ?g/L and 0.033 ?g/L.The recovery of Cr(?)was 95.0-97.7%,while Cr(?)was only 20.5-23.2%due to it was easy to be reduced to Cr(?)in the matrix.The intra-day precision range was 1.18-2.02%,and the inter-day precision range was 3.78-7.46%.Cr(?)and Cr(?)in 21 kinds of marine products were analyzed by HPLC-ICP-MS.The results showed that no Cr(?)was detected in all marine products,and the average content of Cr(?)in shellfish was the highest,ranging from 0.076 to 0.082 mg/kg.Cephalopods took the second place,and the content ranged from 0.039 to 0.052 mg/kg.The average content of Cr(?)in eel was 0.035 mg/kg,while the other 8 species of fish were less than 0.020 mg/kg.The distribution of Cr(?)in crustaceans was not significant and the content was 0.03 mg/kg3.The morphological characteristics of Cr and the transformation of Cr(?)in Mytilus coruscus were studied.Taking Mytilus coruscus as the research object and Cr(?)reference material as the poisoning reagent,it is confirmed that Cr in Mytilus coruscus mainly exists in the form of Cr(?)and organic chromium.In the exposure experiment,the Cr(?)in the Mytilus coruscus was converted into Cr(?)and organic chromium,and the contents of total Cr,Cr(?)and organic chromium in Mytilus coruscus increased significantly.With the increase of Cr content in Mytilus coruscus,the conversion rate of total Cr,Cr(?)and organic chromium gradually decreased,and the content growth rate also gradually slowed down.When Mytilus coruscus in enrichment of equilibrium state,Cr content increase nearly stagnation,the conversion rate of total Cr,Cr(?)and organic chromium decreassed significantly,and the proportion of organic chromium to Cr(?),continued to increase.