| In chromatographic analyses, sample preparation is a neck-step, the efficiency of which is directly related to the reliability, accuracy and throughput of an analytical method. In this dissertation, with the aim to develop sample preparation methods for analyzing complex plant (tobacco) samples, several separation methods were studied, which was proved to be practical and reliable for multicomponent simultaneous determination. The following contents are included:1. At first, sample preparation methods for chromatography analysis emerged in recent years were reviewed, and the most recent application were summarized at the same time. The principal and procedure of cloud point extraction (CPE) were briefly introduced, the applications of CPE to the separation and analysis of organic compounds were summarized, and the problems and solutions when CPE combined with different instruments were also summarized in detail.2. The extraction procedure of pyrethroid residues from tobacco using water as extraction solvent with the aid of ultrasonic followed by the solid phase microextraction (SPME) was established. The whole sampling process, only including an ultrasonic assisted extraction step and a solid phase microextraction step, can be completed within 15min. Quantitative results indicated that four pyrethroids can be determined simultaneously with acceptable sensitivity, recovery and reproducibility permitting analysis to <36ng/g for all pyrethroids by the combination of SPME and GC/MS (SIM).3. Accelerated solvent extraction (ASE), Soxhlet extraction and ultrasonic assisted extraction were compared for their effectiveness in the extraction of terpenoids and sterols from tobacco. The parameters that might affect the ASE were investigated and the satisfactory conditions for the extraction of terpenoids and sterols with different structures were acquired.4. The combination of cloud point extraction (CPE) and GC/MS was realized... |
PDF Full Text Request