The Chemical Form Change Of Pb, As, Cr, Cd In Processing

In this paper,â… had studied several heavy metals lead,arsenic,cadmium,chromium analysis of chemical changes in vegetable processing.The Tessier sequential extraction was used to extract the lead,cadmium chemical form.anion-exchange resin was used to separate the trivalent chromium and hexavalent chromium.Atomic absorption spectrophotometric was used to test its content.Research from the past of heavy metals in the total amount of food transferred to the research study on the form.Further study on the chemical form of heavy metal toxicity has very important significance.The main contents of this paper are:(1) Mensurate the total heavy metals content of lead,arsenic,cadmium,chromium in several vegetables radish,mustard,pepper(2) Mensurate the chemical form of heavy metal Cd,Cr,Pb and As in the pepper in the course of dried and pickled processing(3) Study the chemical form changes of Cd,Cr, Pb and As in the course of radish pickled process,;(4) Study the chemical form changes of Cd,Cr,Pb and As in the course of mustard pickled process.The results of these experiments were shown as follows:1,The content ranges of total lead were 0.351～0.795mg/kg.The Cd content in Chao tian pepper,mustard,radish were 0.25 mg/kg,0.185 mg/kg,0.1375mg/kg, respectively,which were higher than the state standard limitation.but the content of total Cd of the C.frutescens L.was 0.049mg/kg,lower than the state hygienic standard limit of 0.05mg/kg.The content of total chromium in Radish and mustard were higher than the standard limitation,but total chromium of the C.frutescens L and capsicum annuum L was within the limitatiion of state hygienic standard.Arsenic was not detected in sample C.frutescens L and capsicum annuum L.The content of arsenic in radishes and mustard were within the limitation of sate hygienic standard.2,The content of total cadmium,total lead,total chromium in capsicum annuum L.(wet basis) showed an upward trend in dried processing,while the total cadmium, total lead,total lead content in percentage dry basis basically stable.In the dried processing,the content of lead forms were different.in the state 0～4h ethanol lead > water extractable lead > residual bound lead > organic lead.4～14h extractable water lead > ethanol state lead > residue bound lead > organic lead.Residue bound cadmium is the main cadmium in the dried process.The lowest content of cadmium form is inorganic,ethanol cadmium and water extract cadmium transfer before and after 4h into each other.It appears from the overall trend,soluble chromium,organic chromium gradually reduce in the dried processing.3,The concentrations of total chromium,total lead increase with time in pickle juice,There may some chromium and lead penetrate from C.frutescens L,while the concentration of Cadmium in the juice is relatively constant,Initial judge that the cadmium in C.frutescens L was difficult to solve and main forms of cadmium is the residue,followed by ethanol extract cadmium,water extract cadmium,the lowest concentration of cadmium is organic.Ethanol extract cadmium and cadmium residue transform,6h,12h,18h,60h ethanol Cd> residue Cd.Organic cadmium,ethanol cadmium,water cadmium increased with time,and cadmium residues reduce with the time increasing.The lead content of C.frutescens L is as follows:ethanol extractable lead > residual lead > organic lead > water extractable lead.Lead content of residual reduced with time increase,while organic lead and ethanol extractable lead increased with the time increasing.4,At the beginning of pickled radish juice,the total arsenic,total lead,total cadmium content increased,that is to say,part arsenic,lead,cadmium can penetrate into the juice,The dissolvable arsenic is organic arsenic,inorganic arsenic content was small, just up to 2%of the total arsenic.The total chromium can inter-penetrate between radish and juice.The content of lead forms was different,preserved state 3d before ethanol- lead > water extractable -lead> residual- lead > organic-lead.After 30d preserved,the ethanol extractable lead > residual lead > water extractable lead > organic lead.The trend of ethanol extractable lead,residue-lead have been increased,while the organic lead increase first and then reduce,water extractable lead was higher in 1d,and then slowly decline.Organic cadmium content was steady in the beginning of 1d,2d,which were 0.026mg/kg.After 3d,it rose to 0.034mg/kg,after 30d,It is close to zero.Cadmium content in water extract also showed a downward trend.The content of residue cadmium and ethanol extractable cadmium increases with time.Soluble chromium> insoluble chromium> Cr⁶⁺> organic chromium> Cr³⁺.Soluble chromium,Cr⁶⁺,organic chromium,Cr³⁺ reduces with time.The insoluble chromium increased with the time.The total arsenic,inorganic arsenic content decreased in Radish pickled,it has stabilized after 30d.5,The content of total chromium steady increase in mustard juice.The chromium is easy to penetrate from mustard to juice.The Lead,cadmium can penetrate between juice and pickle potherb mustard.The content of cadmium form in 4d:ethanol cadmium > water extractable cadmium > residual cadmium > organic cadmium.In the 10～40d,different forms of cadmium content:ethanol cadmium > residue cadmium > extractable water cadmium > organic cadmium.So a conclusion can be drawn that ethanol cadmium accounts for the main form of cadmium.The main lead form was ethanol extractable lead in Pickled mustard tuber, preserved in the first 4d,the water-extractable lead > organic lead> lead residue.After 10d,the water extractable lead> residual lead > organic lead.For Chromium,In 2d,Soluble Chromium> Cr⁶⁺> Organic Chromium > Cr³⁺,2 20d Cr³⁺ and Cr⁶⁺ transform each other,and in the 3d,the content of Cr⁶⁺ > Cr³⁺,while in the 10d,30d,the content of Cr³⁺> Cr⁶⁺.