Applications Of Capillary Electrophoresis In Natural Products And Environment

Under the background of promoting the development of green analytical chemistry currently, capillary electrophoresis (CE) has many advantages such as high efficiency, short analysis time, small sample size and inexpensive instrumentation, which can be useful in the rapid and efficient determination of active compounds in complex samples. Accelerated solvent extraction (ASE) is a novel preparation method for solvent extraction of solid and semi-solid sample at a higher temperature and higher pressure, due to the outstanding advantages of less organic solvent, extraction speed, high sample recovery rate , has been used in the environment, drugs, food, and polymer industry and other areas of residus. In this paper, two developed methods for the analysis of natural products and amines and their derivatives in Chinese herbal medicines and environment water were presented.1. A very simple, sensitive and highly selective method for directly determining aromatic amines in environmental water by capillary zone electrophoresis (CZE) is described. Field-enhanced sample stacking was used to concentrate the analytes on-line. The parameters influencing the concentration and separation efficiencies were determined. Optimal conditions: 120 mmol/L NaH2PO4, and 10 mmol/L triethanolamine, pH 2.8 as running buffer; sample containing 2 mmol/L phosphate and 60%acetonitrile;operating voltage is 20kv, injection 8kv×6s. Surprisingly, under the optimal conditions, two linear ranges for the calibration plot, 1～50 ng/mL and 50～1000 ng/mL (R > 0.998) were obtained. The limits of detection were in the range of 0.29～0.43 ng/mL. The method was applied to the analysis of water from local rivers. In order to eliminate the effect of the real sample matrix on stacking efficiency, standard addition method was applied for the quantitative analysis.2. A method for the determination of oleanolic acid and ursolic acid in Ligustri Lucidi Fructus using accelerated solvent extraction combined with capillary zone electrophoresis has been developed. The effects of important operational parameters on the performance of accelerated solvent extraction were investigated and optimized. Extraction temperature and cycle times influenced the extraction efficiency considerably, and no obvious effect of extraction time on efficiency was observed. Interestingly, the results showed extraction pressure played an important role in the reproducibility of the extraction process. The optimum extraction conditions included an extraction pressure of 1000psi, an extraction temperature of 100℃and a static extraction time of 5 min with 2 cycles. The parameters influencing the separation efficiency of capillary electrophoresis were observed, and the optimum buffer system was 40 mmol/L borax, 1 mmol/L beta-cyclodextrin, pH 9.5 and 6% methanol. The good linearity was obtained for oleanolic acid and ursolic acid in the range of 10～200μg/mL and 10～160μg/mL, respectively, with the correlation coefficient over 0.996. The limits of detection ranged from 3.2μg/mL to 3.0μg/mL, and the recoveries from 93 to 97%. The contents of oleanolic acid and ursolic acid in Ligustri Lucidi Fructus extracted by accelerated solvent extraction were compared with those resulting from Soxhlet and sonication extraction.