| Liquid-phase microextraction, as its name suggests, makes uses of only a small amount of solvent for concentrating analytes from aqueous samples. It is a new environmental benign sample preparation technique which incorporates sampling, extraction and concentration into a single step. Single-drop microextraction (SDME) is evolved from this technique. Due to its extreme simplicity, many successful applications on organic pollutants analysis have been reported. However, the demerits of single-drop microextraction such as instability of drop, relatively low precision and sensitivity are often encountered. In this dissertation, some innovative research work, based on predecessor works, were carried out as follows:(1) Based on liquid-phase microextraction equilibrium theories, regular equations of the amount of analyte extracted into the acceptor (norg), absolute recovery of the analyte (R) and enrichment factor (E) were proposed.(2) A small bell-mouthed extraction device for single-drop microextraction was prepared by using polytetrafluoroethylene tube. This small device was adopted to assist the drop suspension. Therefore, the drop volume increased and its stability in a stirred sample solution was markedly improved in the single-drop microextraction. By using a small bell-mouthed device to perform SDME, it is very easy to suspend 20μL common organic solvent such as 1-octanol. This improvement was explained in detail. For most high-performance liquid chromatography injections, a sample size of more than 2μL is preferred. However, a small volume of the extracting solvent is usually chosen for the consideration of stability during traditional single-drop microextraction with stirring. By using a small bell-mouthed device to perform SDME, this disadvantage of SDME-HPLC was well overcome.This paper focuses on analytical methods of toxic organic pollutants. It mainly consists of the following six parts:The first part reviews basic principles and extraction modes of liquid-phase microextraction and its application in the analysis of environmental contaminations when used in combination with different analytical techniques, such as gas chromatography, high-performance liquid chromatography, capillary electrophoresis, et al., are summarized. Some limitations are proposed and an outlook on future of the technique is also given.Secondly, a novel headspace SDME with [C4MIM]PF6 as extractant has been developed for the determination of o,p'-DDT, p,p'-DDD, p,p'-DDE, p,p'-DDT in water samples by high-performance liquid chromatography with ultraviolet detection. Under the optimized conditions, the detection limit and precision were in the range of 0.05～0.08μg L～(-1) and 6.8%～8.0%, respectively. Water sample including tap water, well water, snow, reservoir water and Wastewater were analyzed by the proposed procedure and the spiked recoveries are in the range of 86.8-102.6%.Thirdly, a novel method for the determination of 2-nitrophenol, 4-chlorophenol, 2,4-dichlorophenol and 2-naphthol from water samples is described. It based on the combination of headspace SDME with high-performance liquid chromatography-ultraviolet detection. Using [C4MIM]PF6 as extractant, some parameters that maybe influence headspace SDME were investigated. The enrichment factors and repeatability (RSD, n=6) of the proposed method were in the range of 17.2～160.7 and 5.4%～8.9%, respectively. The detection limit for each analyte ranged from 0.3 to 0.5μg l-1. Complex matrices of environmental water samples had a little effect on the enrichment and this problem could be resolved by addition of sodium ethylene diamine tetracetate (EDTA) into the samples. The spiked recoveries were in the range of 89.4～114.2%.In the fourth part, a simple approach to prepare a small bell-mouthed extraction device for single-drop microextraction (SDME) was proposed. Analytical sensitivity was improved by increasing the acceptor volume suspended. Because of the increased contact area and the rough inner surface of the extraction device, the stability of drop was markedly increased. The merits of the proposed method were demonstrated by using 1-octanol as extractant and with cyanazine, simazine and atrazine as model compounds. The related parameters and the effect of humic acid were systematically investigated. Under the optimized extraction conditions, the detection limit (S/N=3) and precision were between the range of 0.03—0. 06μg/L and 5.0-6.7%, respectively. The established method was applied to determine the target compounds in four real water samples, and the spiked recoveries at two concentration levels were in the range of 77.4%—109.7%. Moreover, the comparison of the proposed SDME with the traditional SDME was performed.In the fifth part, a novel method for the determination of thiophanate-methyl and chlorotoluron from water samples by improved SDME in combination with high-performance liquid chromatography-ultraviolet detection was developed. Under the optimum conditions, the enrichment factors were 45.3 and 107.0 folds for thiophanate-methyl and chlorotoluron, respectively. The reasonable detection limits (0.35μg L～(-1)) and suitable repeatability (RSD<9.6%) for both analytes were obtained. The proposed method was validated with three real water samples at two fortification levels, and the spiked recoveries were achieved over the ranged of 84.0%～110.3%.In the last part, a novel method for the determination of 1-naphthylamine, N,N-dimethylaniline and diphenylamine from water samples by headspace improved SDME in combination with high-performance liquid chromatography-ultraviolet detection was developed. Several parameters were optimized for their effects on the extraction performance. The detection limits and precisions were in the range of 0.09-0.38μg/L and 5.8-8.1 %, respectively. The enrichment factors were between 13.7 and 150.8. The spiked recoveries of three water samples were in the range of 81.9—99.1 %.
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