Application Of High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry In Arsenic Speciation Analysis

Trace elements play important roles in the organisms.The toxicity,availability,bioavailability,and migration processes of trace elements are not only related to the total amount of elements,but also depend to great extent on its chemical speciation.Therefore,trace elements and their speciation analysis in biological systems are of great significance.The elemental speciation includes its isotopic composition,valence state,inorganic or organic species,and biological macromolecule species.Arsenic is a widespread element and there are many kinds of speciation in nature and living organisms.Arsenic is toxic and leads to produce carcinogenicity.It is well known that the toxicity of elements depends upon their speciation.Therefore,arsenic speciation analysis has important implications for the field of environmental toxicology and biogeochemical cycles research.Inductivity coupled plasma mass spectrometry(ICP-MS)is one of the most powerful methods for trace/ultra-trace elements analysis due to its outstanding advantages including high sensitivity,high sample throughput,wide linear dynamic range,multi-element detection and isotope analysis ability.The hypheneted technique by combining high performance liquid chromatography(HPLC)with ICP-MS is one of most effective and widely-used methods for elemental speciation.In bioanalysis,the sample volume is always and very limited,the sample matrice are always complex,and elements or their species always occur in extremely low concentration.So that,the accuracy of the determination results of HPLC-ICP-MS will be affected.Therefore,it’s an extremely significance advances of analytical chemistry to explore appropriate sample pretreatment techniques.This dissertation chooses the Arctic shellfish,octopus,and stephania kwangsiensis Lo.as the object of study using HPLC-ICP-MS.The main contents and results are as follows:1.A simple and sensitive method for the analysis of arsenic compounds has been developed using HPLC-ICP-MS.The separation conditions of arsenocholine(AsC),arsenobetaine(AsB),arsenite(AsⅢ),dimethylarsinic acid(DMA),monomethylarsonic acid(MMA),arsenate(AsV)and p-arsanilic acid(P-AsA)were investigated.Under the optimal conditions,seven arsenic speciation can be well separated within 9 min.The LODs(3 σ)for AsC,AsB,As(Ⅲ),DMA,MMA,As(Ⅴ)and P-AsA was 0.237,0.092,0.243,0.054,0.121,0.136 and 0.258 ng mL-1.respectively.The RSDs are less than 3.1%,and the recoveries were between 93.8%and 100.6%.The method was applied for the detection of arsenic species in Arctic shellfish The results show that the arsenic species contained As(Ⅲ),AsC,AsB,DMA and an unknown arsenic compound.The concentrations of As(Ⅲ),AsC,AsB,and DMA were 0.065,0.308,0.098,and 0.102 μg g-1 in Arctic shellfish,respectively.2.A new analytical method for determination of AsC,AsB,As(Ⅲ),DMA,MMA,As(V),P-AsA,and ROX was developed using HPLC-ICP-MS.Extraction conditions es of AsC,AsB,As(Ⅲ),DMA,MMA,As(Ⅴ),P-AsA,and ROX were optimized.Under the optimal conditions,baseline separation of arsenic compounds could be achieved within 14 min.The LODs(3σ)for AsC,AsB,As(Ⅲ),DMA,MMA,As(Ⅴ),P-AsA,and ROX was 0.517,0.276,0.608,0.063,0.129,0.102,0.224 and 0.197 ng.mL-1.And the RSDs ranging in 1.7%～2.7%.In this work,the effects of high purity water,methanol water(1:1),acetic acid(1:19),phosphoric acid(1:19)and enzymatic hydrolysis on the extraction of eight arsenic species were examined.The optimal extractant was acetic acid(1:19).This method was applied for the determination of inorganic and organic arsenic species in Octopus.The results showed that the contents of AsC,AsB,As(Ⅲ),DMA,MMA,and As(Ⅴ)were 0.061,62.2,0.0827,0.0431,0.0486,and 0.0554 μg g-1,respectively.The recoveries were from 94.5%to 102%.The method is simple,easy to operate,and provide a novel procedure for arsenic speciation in aquatic products.3.Arsenic speciation in Stephania kwangsiensis Lo.has been developed using magnetite solid phase extraction(MSPE)coupled with HPLC-ICP-MS.The Fe3O4 magnetic nanoparticles were prepared with the ammonia as precipitant.The surface of magnetite nanoparticles was coated by glycerol-acetic acid catalyzing of tetraethyl silicate(TEOS),The GO with negatively charge was assembled on the surface of the positively charged Fe3O4 @ SiO2 microspheres by electrostatic role.Therefore,Fe3O4 @ SiO2 @ GO magnetic microspheres were obtained.The extraction conditions and elution conditions of MSPE were investigated in detail with As(Ⅲ),As(Ⅴ),DMA and MMA as the target analytes.The detection limits of As(Ⅲ),As(Ⅴ),DMA,and MMA were 0.013,0.038,0.016,and 0.063 ng mL-1,respectively.And the relative standard deviations range from 1.6%to 2.4%.The enrichment factors were varies from 9 to 17-fold.Under the optimal conditions,the actual samples before and after enrichment were been detected,the results show that As(Ⅲ)only were detected in the sample before enrichment,however,arsenic species at the same sample after enrichment can be detected with As(Ⅲ),DMA,and MMA,which are 0.0987,0.0375,and 0.0362 μg g-1,respectively.As(Ⅲ)signal intensity was significantly enhanced,and two arsenic species can be detected.The proposed method is characterized with high enrichment factor,low LODs and fast separation.