Research On Application Of Liquid-Phase Microextraction Based On Hollow Fiber

Liquid microextraction based on hollow fiber (HF-LPME) was a novel technique integrating sampling, extraction, concentration and sample-introduction into one step. It has become one of the hottest fields in analytical chemistry for overcoming the shortcomings of traditional sample preparation technique in time-consuming, tedious, multistage operation and organic solvent consumption. With the benefits of environment friendly, effective and virtually"green", it has many functions of excellent sample clean-up, easily being coupled with a variety of analytical instruments, and diverse operation modes. It has been widely used in the detecting trace and ultra trace contaminations in complex samples.In this paper, the investigations were focused on the application of HF-LPME as sample preparation technique in the preconcentration of nicotine in human plasma, saliva and urine, parathion of environment and aromatic amine in textile. The effective evaluations of the preconcentration were performed by high-pressure liquid chromatography (HPLC). The detail work was as follows:1. Study on the preconcentration of trace nicotine in human saliva and plasma by three-phase liquid phase microextraction (TP-HF-LPME). The polypropylene hollow fiber was used to fix organic extraction and it made the organic solvent and acceptor phase robust under the high stirring rate. The hollow fiber was immobilized by microsyringe needle, the extraction efficiency could be improved and the extraction time could be greatly shorted. The influence factors on the extraction efficiency were studied in details, which were organic solvent, the pH of donor phase, the pH of acceptor phase, stirring rate, and extraction time. The extraction efficiency of preconcentration in trace nicotine in human saliva and plasma was evaluated by the precision and accuracy on the HPLC data. Under the optimum conditions, the proposed method provided linear range of 0.1⁵0 mg/L with r=0.9996, detection limit of 0.05 mg/L (S/N=3), RSD<5% (n=5) and relative recovery of 95.1¹02.4%. The proposed method provided enrichment folds of 21.2. Study on the preconcentration of trace nicotine in human urine based on nano magnetic powder assisted liquid phase microextraction. By the decreasing the bubble generate in stirring process, the nano magnetic powder of Fe₃O₄ was used to modify the extraction efficiency of extract system and replace stirring bar. The influence factors on the extraction efficiency were studied in details, which were the amounts of nano magnetic powder, the quantity organic solvent, the pH of donor phase, the pH of acceptor phase, stirring rate and extraction time. Under the optimized extraction condition, the extraction efficiency of preconcentration in trace nicotine in urine of active and passive smokers was evaluated by the precision and accuracy on the HPLC data. Under the optimum conditions, the proposed method provided linear range of 0.05²5 mg/L with r=0.9997, RSD<3% (n=5). The proposed method provided enrichment folds of 17.9.3. Study on the preconcentration of nicotine in tobacco and cigarette samples using partly immerging liquid phase microextraction. In allusion to the weak volatile characteristics of nicotine, the"partly immerging"extraction mode was introduced and established based on the studies in the factor as organic solvent, extraction time, the pH of donor phase and acceptor phase, stirring speed, salt effect of donor phase, ratio of hollow fiber in gaseous phase and liquid phase. The extraction efficiency of preconcentration of nicotine in tobacco and cigarette samples was evaluated by the precision and accuracy on the HPLC data. Under the optimum conditions, the proposed method provided linear range of 1²00 mg/L with r=0.9997, detection limit of 5μg/L (S/N=3), RSD<5% (n=5) and relative recovery of 97.21⁹9.18%. The proposed method provided enrichment folds of 10.4. Study on the preconcentration of parathion pesticide residue using liquid phase microextraction with ionic liquid as acceptor phase instead of organic solvents with the advantages high selectivity, viscosity, stable and non-volatile. The most typical advantage of ionic liquid was the stable pores presentation in the porous and the satisfaction of higher stirring speed in the extraction. Under the optimized extraction condition, the preconcentration of parathion pesticide residue in environmental water and vegetables samples was evaluated by the precision and accuracy on the HPLC data. Under the optimum conditions, the proposed method provided linear range of 1⁵0μg/L with r=0.9992, detection limit of 0.5μg/L (S/N=3), RSD<5% (n=5) and relative recovery of 81.51⁹2.00%. The proposed method provided enrichment folds of 183.5. Study on the preconcentration of aromatic amine in textile by liquid phase microextraction with ionic liquid as acceptor phase. Based on the national standard methods, HPLC was used to analyze aromatic amine The qualitative and quantitative analysis of 22 aromatic amines in textile., which was announced to be carcinogenical to the human bodies, has been established by HPLC according to the in the national standard method (edited in 1998). The the preconcentration technique of textile sample was improved by the experiments on the effects of the organic solvents, the pH of donor phase, the pH of acceptor phase, stirring rate, extraction time and so on. The introduction of ionic liquid as extractant in liquid phase microextraction technique, was optimized the extraction efficiency of the aromatic amines in the textile and reduced the experimental steps. The preconcentration of aromatic amines in textile samples was evaluated by the precision and accuracy on the HPLC data. The proposed method provided enrichment folds of 270.