Studies On Determination Of Inorganic Elements In Environment And Active Ingredients In Plant By Hplc Methods

Boron and selenium are the essential micronutrients for lives. Trace amounts of them are necessary for healthy. However, they are toxic if taken in excess. Selective and sensitive determination of boron and selenium at trace levels has been strongly required. As ginkgolic acids in Ginkgo biloba are claimed to be allergenic, mutagenic and slight neurotoxic, their presence is considered undesirable in Ginkgo leaves extracts. Meanwhile, ginkgolic acids also have some specific pharmacological activities such as antibiotic and anti-virus. Therefore, it is important to develop a sensitive method to determine the ginkgolic acids in Ginkgo biloba and Ginkgo leaves extracts. In this thesis, the high performance liquid chromatography (HPLC) methods to determine boron/selenium in environment and ginkgolic acids in Ginkgo biloba were studied.At first, the HPLC methods following derivatization to determine trace amounts of boron and selenium in environmental samples were developed. For the analysis of boron, the complex of boron-chromotropic acid was separated on a Mightysil C18column (150×4.6mm) with water-methanol (41:59) as mobile phase, at a flow rate of1mL min-1, and was detected by UV detector at350nm. The obtained calibration curve showed good linearity over a concentration range from0to6×10-5mol/L with regression coefficient of0.9993for boron. The detection limit (LOD) was1×10’7mol/L for boron corresponding to100μL injection. For the analysis of selenium, the complex of selenium-DAN (2,3-diaminonaphtalene) was separated on a Mightysil C18column (150x4.6mm) with cyclohexane-THF (97.5:2.5, v/v) as mobile phase, at a flow rate of1mL min-1, and was detected by fluorometric detector with excitation wavelength of380nm and emission wavelength of530nm. The linearity was satisfactory over a range of0.25～2×10-9mol/L with regression coefficients of0.9921. The detection limit was1.7×10-11mol/L for selenium. The influence of foreign ions on the HPLC determination was also examined. Then, the optimized methods were used to analyze the environmental samples from river and soil. The content in the rivers for boron and selenium ranged from5.5to20.1μg/L and2.0to5.5μg/L, respectively, which were similiar to those reported by literatures. The selenium content in soil samples also corresponded to the values certified.Then, a simple and reliable HPLC method was developed to determine ginkgolic acids in Ginkgo biloba samples such as leaves, sarcotesta and seeds etc. Ginkgolic acids in samples were extracted with methanol and then purified by liquid-liquid extraction with hexane. The separation of ginkgolic acids was performed on Waters Symmetry-C18column with methanol-water (containing5%acetic acid)(88:12, v/v) as moblie phase and with UV detection at310nm. The calibration curves of5main ginkgolic acids showed good linearity with the correlation coefficients of0.9999. The detection limits were between0.26～1.37mg/L. The extraction recovery ranged from97.3%to102.6%for ginkgolic acids with RSD of6.83%(n=5). This potential of the proposed method was assessed by applying it to determination of ginkgolic acids in Ginkgo biloba samples. The content of ginkgolic acids in sarcotesta was higher than other samples, and those in seeds was the least, which corresponded to those reported by literatures. The results prove that it is a simple and sensitive method suitable for both high and low levels of ginkgo acids in Ginkgo biloba samples.