Magnetic Solid Phase Extraction Coupled With ICP-MS For Heavy Metals Analysis And Speciation

Heavy metals have been used in numerous fields of human activities for thousands of years.Heavy metals pollution,caused by the rapid development of modern industry and agriculture,has gained extensive attention.As we all know that human intake of toxic metals(such as Cd,Hg and Pb)can cause a series of toxicities or side effects to kidney,liver or nervous.The toxicity and biocompatibility of heavy metals is closely relative to their species.Therefore,it is of great significance to establish high sensitive methods for heavy metal analysis and speciation in environmental and biological samples.Inductively coupled plasma mass spectrometry(ICP-MS),one of the most powerful element-specific detection technologies,has advantages of high sensitivity,low detection limit,good precision,wide linear range and multielement detection capability.Besides,it can be easily combined with high performance liquid chromatography(HPLC),which is widely used in elemental speciation.But several problems often hamp its application in real samples,such as lacking of selectivity to elemantal species,matrix interference and sometimes insufficient sensitivity.Therefore,it is necessary to choose proper sample pretreatment technique to concentrate target metal ions/species as well as remove sample matrix.Magnetic solid phase extraction(MSPE)has advantages of high enrichment factor,convenient operation,fast phase separation,and has been widely used in heavy metal analysis and speciation.The analytical performance of MSPE is mainly dependent on the magnetic adsorbents.And the development of novel functional magnetic materials with excellent selectivity,stability and fast adsorption-desorption dynamics is very important.The purpose of the dissertation is to develop novel material of MSPE for the analysis of heavy metals,and develop new methods combining MSPE with(HPLC)-ICP-MS for the analysis and speciation of heavy metals.The main contents are described as follows:(1)Fe3O4@SiO2@nitrogen doped nanoporous carbon(NPC)magnetic nanoparticles was synthesized by one pot strategy and a new method of MSPE-ICP-MS was developed for the analysis of trace Cd2+,Hg2+ and Pb2+ in environmental water samples.Various parameters affecting Fe3O4@SiO2@NPC-based MSPE of target metal ions have been investigated.Under the optimized conditions,the limits of detection for Cd2+,Hg2+ and Pb2+ were 0.74,1.9 and 5.7 ng L-1,respectively.The developed MSPE-ICP-MS method was validated by the analysis of Cd2+,Hg2+ and Pb2+ in the Certified Reference Materials of GSB07-3173-2014(202041)and GSBZ50009-88(200928).It was then used for the analysis of trace target metal ions in environmental water as well as tap water,and the recovery was in the range of 88.1-108%.(2)Fe3O4@SiO2@?-mercaptopropyltrimethoxysilane(?-MPTS)magnetic nanoparticles was prepared and a new method of MSPE-HPLC-ICP-MS was developed for the simultaneous speciation of mercury including inorganic mercury(Hg2+),methylmercury(MeHg+)and phenylmercury(PhHg+)in environmental water and fish samples.A rapid separation of three target mercury species was achieved in 8 min by employing relatively high ratio of methanol in HPLC mobile phase.Various parameters affecting Fe3O4@SiO2@y-MPTS-based MSPE of target mercury species have been investigated.Under the optimized conditions,the limits of detection for Hg2+,MeHg+ and PhHg+ were 0.74,0.67 and 0.49 ng L-1,respectively.The developed MSPE-HPLC-ICP-MS method was validated by the speciation of mercury in the Certified Reference Material of DORM-2 dogfish as well as real-world samples including environmental water,wastewater,tap water and fish samples,and the recovery was in the range of 81.7-110%.