Study On Capillary Electrophoresis-capacitively Coupled Contactless Conductivity Detection Combined With Novel Sample Preconcentration In Trace Analysis

1.PrefaceAs an efficient and versatile separation technology,capillary electrophoresis(CE)has been widely used in environmental,biological,pharmaceutical,food analysis and other fields.In this chapter,the separation principle of CE,current situation and development trend of capacitively coupled contactless conductivity detection(C~4D),the principle and application of novel sample preliminary enrichment technology were introduced respectively.The purification and enrichment performance of novel sample preliminary enrichment technology was combined with efficient CE and versatile C~4D,for the analysis of biological samples and foods.Without derivatization procedure,this method is easy to operate,sensitive and friendly to environment.2.Hollow-fiber liquid-phase microextraction of short-chain fatty acids in microbial degradation fluid using CE-C~4DAssisted by tributyl phosphate,this hollow-fiber liquid-phase microextraction coupled with capillary electrophoresis-contactless coupled conductivity detection(HF-LPME/CE-C~4D)method has been successfully developed for the determination of trace short-chain fatty acids(SCFAs)in microbial degradation fluid.Without derivatization,ten SCFAs(including a pair of isomers)were well separated from their homologous FAs and the main coexisting inorganic anions under the optimum separation conditions.Microbial degradation fluid was taken as high salt matrix sample model,the established HF-LPME method with TBP as supporting liquid membrane can provide good purification and enrichment performance,the limits of detection could reach 0.072-0.67 ng/m L(S/N=3).Due to the satisfactory sensitivity,excellent linearity,and acceptable recovery,this HF-LPME/CE-C~4D method could be a sensitive and environment-friendly alternative for trace analysis of SCFAs in complicated matrix.3.Synergetic stacking for the sensitive determination of sialic acids in dairy products using CE-C~4DBased on the CE-C~4D system,moving chemical reaction boundary(MCRB)combined with field amplified sample injection(FASI),this synergetic stacking technology was developed for the sensitive determination of two major sialic acids,N-acetylneuraminic acid(NANA)and N-glycolylneuraminic acid(NGNA).A series of experimental parameters(including parameters affecting the hydrolysis,separation,and detection of sialic acid)were optimized,NANA and NGNA could be well separated from the common carbohydrates as well as other potential coexisting inorganic and organic anions.With high sensitivity(LODs 1.7–2.2 ng/m L),good linearity(r>0.999),acceptable recovery(93–107%),and reliability of acid hydrolysis step in determining target analytes from dairy products,this proposed method could provide a simple,rapid,sensitive,and environmentally friendly alternative for the analyses of the main sialic acids,which further extends the application of CE-C~4D.