Study On The Analytical Methods Of Trace Substances By Nanomaterials-based Sample Microextraction Coupled With Capillary Electrophoresis Technology

1.PrefaceCapillary electrophoresis（CE）has been developed into a mature separation and analysis technology with various models and wide applications,which can be combined with a variety of detectors.Among them,the combination of CE and the universal capacitance-coupled non-contact conductance detection（C⁴D）technology has a broad application prospect in the fields of biological,drug,food and environmental analysis due to its inherent characteristics.However,C⁴D is not enough sensitive to meet the direct and sensitive detection of low-content analytes in the complex samples.The green sample pretreatment technologies provide new approaches for the purification and selective extraction of complex samples.In this chapter,on the basis of a brief overview of CE-C⁴D combination technology and its research progress in different fields,the mechanism of dispersive micro-solid phase extraction（DMSPE）,electromembrane extraction（EME）and other extraction technologies,as well as the research progress of nanomaterial application in these fields were emphatically reviewed.2.Study on the trace analysis method of low-molecular-weight thiols in saliva by DMSPE/CE-C⁴D technologyIn this work,an analytical method was developed for the extraction and determination of low molecular weight thiols,which combined Tween 20-capped gold nanoparticles DMSPE（Tween 20-Au NPs-DMSPE）,CE-C⁴D and the on-line field amplified sample stacking technologies.Tween 20-Au NPs could provide good purification and selective enrichment of four main low-molecular-weight thiols（homocysteine,cysteine,methionine and reduced glutathione）,and the obtained desorption liquid was directly injected and analyzed by CE-C⁴D without derivatization.In the experiments,ultrasound was introduced to speed up the desorption process and reduce the sample pretreatment time,and the synergistic effect of on-line field amplified sample stacking and off-line enrichment was achieved,which further improved the detection sensitivity.Under optimized conditions,the four low-molecular-weight thiols could be well separated from the main potential interferences,and this developed method was successfully applied to the analysis of saliva samples.The detection limits of the four thiols in saliva sample matrix were0.15-1.5 ng m L^-1（S/N=3）,and the recoveries were 97.6-116%.This method provides an alternative for the sensitive determination of low-molecular-weight thiols in the noninvasive body fluids.3.Study on the trace analysis method of biological amines in wate by EME/CE-C⁴D technologyIn this work,an analytical method of typical fatty biogenic amines was developed by combining EME,which integrates purification and enrichment,CE-C⁴D and the field amplified sample stacking technologies.The supporting liquid membrane of EME with synergistic modification by quantum dots and ion carriers（ionophore bis（2-ethylhexyl）phosphate and trioctyl phosphate）could provide good purification and selective enrichment for four aliphatic biogenic amines（spermine,spermidine,putrescine,cadaverine）,and the extracted solution could be directly injected and analyzed by CE-C⁴D.The effects of key parameters,including the types and contents of nanomaterials and ionic carriers,on the enrichment performance were investigated,and the synergistic effect of online FASS and offline EME enrichment further improved the detection sensitivity.Under the optimized conditions,the target analytes could be well separated from the main potential interferences,and this developed method was successfully applied to the analysis of tap water samples.The detection limits were 0.060-6.0μg L^-1（S/N=3）and the recoveries were 89.4-114%in the actual water sample matrix.This method had a short sample pretreatment time and required no derivatization,which provided a potential new method for monitoring the level of microbial contamination in water quality.