Study On Trace Of Analytes By Separation/Preconcentration Micellar Electrokinetic Capillary Chromatography

Micellar electrokinetic capillary chromatography(MEKC),introduced by Terabe et al in 1984,has become one of the most important modes of capillary electrophresis for its ability to analyze neutral analytes.The aim of this dissertation is to develop the techniques of combination of MEKC with cloud point extraction(CPE)and field-amplified sample injection(FASI)for trace analysis.Efficient and sensitive methods were developed for the determination of triptonide in Chinese herbal medicines,hydrophobic benzophenones in sunscreen,and albumin(Alb)and transferring(Tfi)in urine with kidney diseases.The major contents are described as the follows:1.A method has been developed for the determination of triptonide in traditional Chinese herb Tripterygium wilfordii Hook F.by MEKC combined with cloud point extraction.Various parameters affecting CPE were optimized systematically.Under the optimize conditions,an enrichment factor of 25 was obtained and the determination limits of was found to be 5.98×10^-7mol/L mol/L.The proposed method has been successfully applied to the determination of triptonide in T.wilfordii tablet and spiked urine samples,demonstrating the feasibility and reliability of the proposed method.2.A method has been developed for the separation and determination of three hydrophobic benzophenones:2,4-dihydroxybenzophenone(BP-1),2,2',4,4'-tetrahydroxy-benzophenone(BP-2)and 2-hydroxy-4-methoxybenzophenone(BP-3)in sunscreen by MEKC combined with cloud point extraction.Various parameters affecting CPE and MEKC separation were optimized systematically.Under the optimized conditions,an enrichment factor of 20 was obtained and the determination limits of BP-1, BP-2 and BP-3 were found to be 3.90×10^-7mol/L,3.83×10^-7mol/L and 6.42×10^-8mol/L, respectively.The presented procedure was successfully applied to the determination of BP-1,BP-2 and BP-3 in sunscreen with satisfactory results.3.An online concentration method in MEKC applying FASI mode was developed for the detection of Alb and Tfi in urine with kidney diseases.The conditions of MEKC separation and FASI preconcentration were systematically optimized.By using the online concentration method of FASI stacking,the sensitivity was increased 77.6-fold and 45.3-fold for Tfi and Alb,respectively.Under the optimized conditions,the determination limits of Tfi and Alb were found to be 0.24 mg/L and 0.46 mg/L, respectively.The proposed method was successfully applied for the determination of the two proteins in urine with kidney diseases.