Sample Pre-treatment Technology For HPLC Analysis Of Environmental And Pharmaceutical Samples

Chromatographic analysis is the most important detection method in analytical chemistry, which has been widely applied in the field of medicine, environment, life science, and petrochemical research. In the analytical process, the sample matrices are always complicated, and the analytes are with low concentration in the environment. Thus, in order to avoid the interference, improve the sensitivity, insure the accuracy of the results, the sample pre-treatment become of great importance. With the advances of science, especially for the instrument and analytical technology, sample pre-treatment has addressed tremendous attentions of scientists. For developing simple, quick and environmentally-friendly method, we have carried out the following works.1. In this paper, ionic liquid （IL）-coated magnetic Fe₃O₄ nanoparticles （NPs） as adsorbent of mixed hemimicelles solid-phase extraction （SPE） was investigated for the preconcentration of polycyclic aromatic hydrocarbons （PAHs） from environmental samples. Due to the high surface area and excellent adsorption capacity of the Fe₃O₄ NPs after modification with ILs, satisfactory extraction recoveries can be achieved with only 80 mg Fe₃O₄ NPs, 50 mg IL, 300 mL solution at pH =10 and 10 min for equilibration. A comprehensive study of the adsorption conditions such as the amount of Fe₃O₄ NPs and ionic liquids, the solution pH, ionic strength, standing time, breakthrough volume, and desorption solvents was presented. The extraction ability of different coating agents, such as 1-hexadecyl-3-methylimidazolium bromide （C16mimBr）, 1-decyl-3-methylimidazolium bromide （C10mimBr） and cationic surfactant cetyltrimethylammonium bromide （CTAB） was also compared. Under the optimized conditions, the satisfactory recoveries for the water and soil samples analysis were between 73% and 105%。2. A methodology based on anionic surfactant-mediated ultrasonic micellar extraction has been optimized and applied to extract chlorophenols in soil samples, followed by high-performance liquid chromatographic （HPLC） analysis without clean-up steps. This study was carried out using an anionic surfactant, sodium dodecyl sulfate （SDS） as extracting medium. No organic solvents were used in the extraction, making this method environmentally friendly and more attractive than the conventional organic solvent-based extraction methods. The affecting variables, such as surfactant concentration, surfactant volume, pH of the solution and extraction time were determined.This method was successfully applied to fresh samples as well as to aged samples for the analysis of soils. The proposed method provides a simple, fast and organic solvent-free procedure for the sample preparation of solid environmental samples.3. A new cloud-point methodology based on acid-induced cloud-point phenomenon of anionic surfactant has been first invetstigated to determine cryptotanshinone and tanshionen IIA in human urine by high performance liquid chromatography with ultraviolet detection. The anionic surfactant sodium dedocyl sulfate （SDS） was chosen as the extract solvent. Variable parameters, sucha as surafactant concentration, HCl concentration, equilibrium time and temperature, affecting the CPE efficiency were evaluated and optimized. Under the optimum conditions, the method was shown to be reproducible and reliable with precision below 6%, and relative recovery ranging from 93.9-102.8%, which were all calculated using a range of spiked samples at three concentrations of 0.2, 0.5 and 5μg /mL for both CT and TS in urine.