Establishment And Application Of Speciation Analysis Method Of Selenium,Arsenic And Mercury In Feed

In this study,feed samples were used as the research object,different species detection methods of selenium,arsenic and mercury were established by using high performance liquid chromatography hydride generation atomic fluorescence spectrometry（HPLC-HG-AFS）.The extraction conditions of the samples were selected,and the chromatographic and spectral conditions of the instrument were optimized.The major results and conclusions are summarized as follows:（1）A rapid and sensitive method using HPLC-HG-AFS has been developed for the simultaneous determination of five selenium species Se（Ⅵ）,Se（Ⅳ）,SeMet,SeMeCys and SeCys₂ in Se-enriched yeast.The isolation of the analytes from yeast samples was accomplished using enzymatic probe sonication.The target compounds were separated on a PRP-X100 anion exchange column and analyzed by HG-AFS.The mobile phase was 25 mmol/L（NH₄）₂HPO₄.Good linearity was obtained for all the four selenium species,with correlation coefficients higher than 0.9995.The LODs of five species were between 1 and 10μg/kg.Average recoveries for the four analytes were in the ranges of 85.8%-102.5%,with intra-and inter-day repeatability lower than 6.1%and 9.6%,respectively.This validated method was successively applied to the determination of selenium species in Se-enriched yeast.The results indicated that the main species of the yeast were Se（Ⅳ）,SeMet,and SeMeCys.This method can quickly analyze five selenium species of feed,and has the advantages of simple pretreatment,equipment cheap,suitable for speciation analysis of selenium in bulk feed sample,it can be used widely in feed industry.（2）A sensitive and rapid method using HPLC-HG-AFS has been developed for the simultaneous determination of seven arsenic species As（Ⅲ）,As（Ⅴ）,MMA,DMA,p-ASA,4-OH and ROX in feeds.The isolation of the analytes from feed samples was accomplished using methanol water（1:1）.The target compounds were separated on a PRP-X100 anion exchange column and then analyzed by HG-AFS.The mobile phase was 15 mmol/L（NH₄）₂HPO₄ and 10 mmol/L potassium acid phthalate.Good linearity was obtained for all of the seven arsenic species,with correlation coefficients higher than0.9964.The LODs of the seven arsenic species were between 5 and 30μg/kg.Average recoveries for the seven analytes were in the ranges of 76.3%-108.1%,with intra-and inter-day repeatability lower than7.69%and 17.42%,respectively.This validated method was successively applied to the determination of arsenic species in feeds.The proposed analytical method is sensitive,simple,cheap and low operation cost,making it applicable for the determination of the arsenic species in feeds.（3）A sensitive and rapid method using HPLC-HG-AFS has been developed for the simultaneous determination of three mercury species Hg²⁺,MeHg and EtHg in feeds.The isolation of the analytes from feed samples was accomplished using 5 mol/L hydrochloric acid.The target compounds were separated on a Venusil MP C18 column and then analyzed by HG-AFS.Three kinds of mercury species can be completed separated within 10 minutes.The mobile phase was 3%acetonitrile+60 mmol/L ammonium acetate+10 mmol/L L-cysteine.Good linearity was obtained for all of the three mercury species,with correlation coefficients higher than 0.9976.The LODs of the three mercury species were between 3 and 5μg/kg.Average recoveries for the three analytes were in the ranges of 79.5%-103.8%,with intra-and inter-day repeatability lower than 11.3%and 21.1%,respectively.This validated method was successively applied to the determination of mercury species in feeds.The proposed analytical method is sensitive,simple,cheap and low operation cost,making it applicable for the determination of the mercury species in feeds.