| Micellar electrokinetic chromatography (MEKC) has become one of the mostimportant modes of capillary electrophresis, since it is suitable for the separation of neutral aswell as charged molecules. Lauric acid micellar buffer system exhibit much reducedconductivity and high electroosmotic flow compared to traditional MEKC buffers. Thereduced conductivity allowed for the application of much higher electric fields, resulting invery fast analysis times. In particular, the fact that the lauric acid micellar buffer systemsdiscussed here do not contaminated of the ionization source, and allows for MEKC couplewith mass spectrometric (MS) detection.In this thesis, the development and applications of MEKC and MEKC-MS werereviewed. The basic principle and characteristic of MEKC were introduced. The followingaspects were investigated by using lauric acid surfactant:1. MEKC-UV and MEKC-MS methods for rapid determination of eight triazine herbicideswere developed by using lauric acid buffer system, respectively. MEKC-UV method canbaseline separation of eight triazine herbicides within 2.2 mins, this is obviously rapid thanother reported methods. The compatible of MEKC and MS was resolved successfully sincethe contamination of the ionization source can be avoided by using laurie acid as thesurfactant. The detection limit, with solid phase extraction(SPE), varied from 0.040 to 0.10μg/L. The average recoveries of eight herbicides from farm water ranged from 88.0% to96.6%.2. MEKC-UV and MEKC-MS methods for rapid determination of seven carbamate pesticedes was developed by using lauric acid buffer system, respectively. The detection limit of eachanalytes varied from 0.08 to 0.18μg/L with SPE. The average recoveries of seven analytesfrom farm water ranged from 87.1% to 93.9%.This method is rapid, simple and selective. Theresults demonstrated the laurie acid buffer system have a good practicability for MEKC-MS.3. Using SDS-lauric acid mixed mieelles as pseudo-stationary phases, the separation anddetermination of nine sex hormones in norethisterone tablets and Penis et Testis Cervi methodwas developed. The mixed micelles supply a gap of each other and avoid use expensivereagent such as cholate and cyclodextrin which used in other reported methods. Under theoptimized conditions, the baseline separation of nine sex hormones, which structures areextremly similar, were achieved within 13.5 mins. The detection limit of each analytes variedfrom 0.20 to 2.7 mmol/L with the ultrasonic-solid phase extraction. The average recoveries ofnine sex hormones ranged from 85.0% to 109% for all with RSDs below 5.5%(n=5).4. Four pesticede and six hormones were selected as test compounds respectively. Threeon-line preconcentration strategies were investigated. The the influences of the concentrationof sample matrix on the stacking efficiency of these analytes in SDS buffer system werediscussed. The concentration enhancement of these analytes were investigated and contrasted.The results demonstrated stacking with reverse migration micelles (SRMM) is the bestpreconcentration strategies for pesticede and hormones. |
