Gold Nanoparticles Modified Polymer Monolithic Capillary Microextraction Combined With Inductively Coupled Plasma Mass Spectrometry For Trace Elements Analysis

Due to the rapid development of the modern industry,metal products are widely used,and metal pollution incidents occur frequently,which threaten human health seriously.Therefore,the detection of trace metals in biological and environmental samples is of great significance.Inductively coupled plasma mass spectrometry(ICP-MS)has various advantages in trace elements analysis,such as high sensitivity,wide linear range,fast analysis,and multi-element detection capability.But for real-world samples analysis,the matrix is usually complicated and the target elements contents are too low to be directly detected by ICP-MS.Hence,suitable sample pretreatment techniques are often needed before ICP-MS detection.As a miniaturized sample pretreatment technique,polymer monolithic capillary microextraction(CME)is featured with low consumption of sample,easy preparation,high adsorption capacity and easy-to-hyphenate with different analytical instruments.In order to improve the extraction performance of polymer monolithic capillary for interest analytes,modification is generally needed.Presently,more and more nano materials have been used to modify the polymer monolithic capillary.Au nanoparticles(NPs)are featured with easy preparation,high stability and high affinity to thiol groups.Besides,the large specific surface area and plenty of active sites of Au NPs make the amount of functional groups on the monolith easily amplified by Au NPs modification.Au NPs modified polymer monolithic capillary has been widely used for analysis of biomacromolecules such as polypeptides and proteins in biological samples,while its application in trace elements analysis is relatively scarce due to the lacking of appropriate polymer monolith.The purpose of this dissertation is to prepare Au NPs modified polymer monolithic capillary with high affinity to interest elements,and develop new methods of on-line CME-ICP-MS for trace elements analysis in environmental and biological samples.The main contents of this dissertation are described as follows.(1)Au NPs modified poly(glycidyl methacrylate-ethylene dimethacrylate)(poly(GMA-EDMA-Au NPs))monolithic capillary was prepared and modified with mercaptosuccinic acid(MSA),and a novel method based on polymer monolithic CME on-line combined with ICP-MS was developed for the analysis of rare earth elements(REEs)in environmental and biological samples.Various factors affecting the extraction efficiency were investigated,including adsorption conditions and elution conditions.Under the optimized conditions,the analytical performance was evaluated.The limits of detection were in the range of 0.16(Tb)-0.85(Gd)ng L-1.The relative standard deviations were between 2.7%(Lu)and 9.8%(Dy).The enrichment factor was 25-fold with the sample throughput of 10 h-1.With the modification of Au NPs,the adsorption capacity of the monolith towards target REEs was improved by 3 to 6.5 times.The accuracy of the method was validated by the analysis of Certified Reference Materials(CRMs)of GSB04-1789-2004(water)and GBW07301a(stream sediment).The proposed method was applied for the analysis of trace REEs in seawater samples as well as human whole blood,and the recoveries for the spiked samples were in the range of 81.1-116%.(2)L-cysteine(L-Cys)modified poly(GMA-EDMA-Au NPs)monolith was prepared,which exhibited good preparation reproducibility and chemical stability.Based on it,a method combining polymer monolithic CME with on-line ICP-MS detection was developed for the analysis of transition metals in cell samples.Various factors affecting the extraction efficiency were investigated.Under the optimized conditions,the limits of detection were in the range of 0.45(Eu)-15.41(Cu)ng L-1.The relative standard deviations were between 3.0%(Ce)and 9.3%(In).HepG2 and SCC-7 cells were analyzed after ultrasonic wall breaking,and the content of target metals was found to be at fg-sub fg level per cell,with recoveries of 85.4-116%in the spiked samples.The developed method merits low sample consumption,low detection limits and high sample throughput(10h-1)with great application potential in the analysis of precious biological samples such as cells.