| In this thesis, triazine、sulfonylurea, and acetanilide herbicides were choosed as target analytes and ionic liquids foam flotation-based extraction method coupled with high performance liquid chromatography was applied to extraction, separation, enrichment and determination of the analytes. The residues of three kinds of herbicides in vegetable, corn, soybean, milk, and rice were studied.The ionic liquid foam floatation solid phase extraction was established and applied to the extraction of six triazine herbicides, including desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn and dipropetryn, in vegetable samples. To obtain the optimized experimental parameters, the effects of p H value of sample solution, the type and concentration of ionic liquid, the flow rate of carrier gas, foam floatation time, the type of solid phase extraction cartridge, the type and volume of elution solvent on the recoveries of the analytes were examined. The high performance liquid chromatography was applied to the determination of the analytes. Under the optimized experimental conditions, a good linearity was observed in the concentration range of 5.00-160.00 μg?kg-1. The limits of detection for desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn and dipropetryn were 2.50, 1.75, 2.76, 1.87, 1.36 and 1.44 μg?kg-1 respectively. The real samples were analyzed and the results were satisfactory. The recoveries ranged from 78.64 % to 104.37 % and the precision was between 1.44 and 6.45 %.Ionic liquid-based foam flotation followed by solid phase extraction was developed for extraction of eight triazine herbicides, including cyanazine, metribuzin, desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn and dipropetryn in corn samples. When the ultrasonic-assised extraction was completed, the analytes were separated from the sample matrix by foam flotation and introduced into the solid phase extraction cartridge. The separation and concentration of target analytes were performed simultaneously. The analytes eluted from the solid phase extraction cartridge were determined by high performance liquid chromatography. The effects of experimental parameters of extraction and flotation were examined. Under the optimized experimental conditions, a good linearity was obtained in the range of 2.50-150 μg?kg-1. The detection limits of the triazine herbicides were in the range of 0.74-1.62 μg?kg-1. The present method was successfully applied to the analysis of corn samples. The recoveries ranged from 85.9 % to 104.0 % and the relative standard deviations were lower than 5.6%.The ultrasound-assisted ionic liquid foam flotation solid-phase extraction of sulfonylurea herbicides in milk was developed and validated. The proteins and lipids were isolated from the sample matrix by adding salt and adjusting p H value. The target analytes eluted from the solid-phase extraction cartridge were determined by high performance liquid chromatography. Some experimental parameters, including the p H value of sample solution, amount of Na Cl, ionic liquid type, extraction time, flow rate of carrier gas, flotation time and solid phase extraction cartridge type were investigated and optimized. Under the optimized experimental conditions, the limits of detection for metsulfuron, pyrazosulfuron, chlorimuron-ethyl, and nicosulfuron were 1.3, 0.6, 0.7, and 1.1 μg?L-1, respectively. When the present method was applied to the analysis of milk samples the recoveries of the analytes ranged from 84.3 to 105.2% and relative standard deviations were lower than 5.7%.Ionic liquid foam-based solvent floatation coupled with high performance liquid chromatography was developed for extraction, separation and determination of four triazine herbicides, including terbumeton, terbuthylazine, dimethametryn and dipropetryn, from soybean samples. The floatation and concentration of target analytes were performed simultaneously. The effect of experimental parameters of flotation and extraction, including the p H value of floatation solution, type of floatation solvent, kind of ionic liquid and floatation time, was investigated and optimized. Under the optimized experimental conditions, the linearity was in the range of 1.5-300.0 μg?kg-1. The detection limits for terbumeton, terbuthylazine, dimethametryn and dipropetryn were 1.1, 1.8, 0.6, and 0.5μg?kg-1, respectively. The present method was successfully applied to the analysis of soybean samples. The recoveries ranged from 84.5 % to 106.8 % and the precision was lower than 5.1%.Ionic liquid-based matrix solid phase dispersion-solvent flotation coupled with high performance liquid chromatography was developed for the determination of the acetanilide herbicides, including metazachlor, propanil, alachlor, propisochlor, pretilachlor, and butachlor in rice samples. Some experimental parameters, including the type of dispersant, the mass ratiosratios of dispersant to sample, p H of sample solution, the type of extraction solvent, the type of ionic liquid, flotation time, and flow rate of N2 were investigated and optimized. The average recoveries of the acetanilide herbicides at spiked concentrations of 50, 125, and 250 μg?kg-1 ranged from 89.4 % to 108.7 %, and relative standard deviations were equal to or lower than 7.1%, The limits of quantification were in the range of 38.0-84.7 μg?kg-1.In the thesis, pretreatment methods of five different types sample, including vegetables, corn, milk, soybean, and rice, were investigated and established. The samples with different characteristics were suggested to choose different pretreatment methods. The foam flotation solid phase extraction was used to pretreat liquid samples, such as milk. The poteins and liqids didn’t need to be removed but just need to be precipitated with the reactives before analysis. The extractant can be directly injected into high performance liquid chromatograph. The extraction of analytes in vegetables samples is easy because of high water content. In order to ensure representative of results, sample amount can be large. The foam flotation solid phase extraction can be selected for separation and enrichment of analytes. The three grain samples, including corn, soybean, and rice, are solid particles. The extraction yield is low when the analytes in these solid samples is extracted directly. So some other methods such as the ultrasonic assisted extraction before the foam flotation should be required for increasing the extraction yield. |
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