Novel Solid Phase Extraction Coupled With High Performance Liquid Chromatography For The Determination Of Microcystins And Sulfonylurea Herbicides In Water Samples

Due to the complexity of matrix components and the trace level of analytes inenvironmental samples, the sample pretreatment techniques play an important rolebefore the instrumental analysis. Sample pretreatment techniques help researchersachieve the purpose of enrichment and purification. Solid phase extraction is a widelyused sample pretreatment technique for the determination of environmental pollutants.Some efficient, fast and convenient novel sample pretreatment techniques based onSolid phase extraction are more and more aroused people’s concern. This thesis hasstudied on two recently developed sample pretreatment techniques-magnetic solidphase extraction and solid phase extraction disk for enrichment of microcystins andsulfonylurea herbicides in water. This paper applied the novel solid phase extractioncombined with high performance liquid chromatography to the detection ofmicrocystins and sulfonylurea herbicides in environmental water samples.This studyhas finished the following work.(1) Magnetic solid phase extraction based on the composite magneticnanoparticles was developed for the enrichment of microcystin-LR in water. Thecharacterization of magnetic nanoparticles was conducted. Under optimizedextraction condition (type and volume of desorption solvent, time, pH, salt effect),this method was successfully applied to the analysis of microcystin-LR in watersamples. The results showed that good linear relationship (r2=0.9995) was obtainedbetween peak area and concentration of microcystin-LR in the range of0.2-5.0μg/L.The detection of limit was0.056μg/L. The recovery of microcystin-LR in spikedsurface water sample was74.7%with relative standard deviations less than4.3%. Themethod was rapid, sensitive and provided a new route for the determination ofmicrocystin in environmental water.(2) A rapid analytical method based on C18solid phase extraction disk followedby high performance liquid chromatography for the determination of six tracesulfonylurea herbicides in water was developed. Chromatographic conditions were optimized and the factors that influenced the extraction, including type and volume ofdesorption solvent, pH value of sample and amount of salt addition were investigated.Under the optimal conditions, good linear relationships (r2>0.9990) were obtainedbetween peak area and concentration of6sulfonylurea herbicides in the range of1.0-20.0μg/L for tribenuron and0.05-20μg/L for rest of the target compounds. Thedetection limits were in the range of0.019-0.037μg/L. The recoveries of6sulfonylurea herbicides of spiked water sample and seawater sample were in the rangeof92.6%-105.7%and89.8%-108.7%, with relative standard deviations (RSDs) of0.7%-7.1%and0.5%-4.0%, respectively. The method was simple, rapid, accurate,sensitive, and could provide a new option for the determination of sulfonylureaherbicides in environmental water.(3)Solid phase extraction column coupled with high performance liquidchromatography for the detection of six trace sulfonylurea herbicides in water wasdeveloped. The factors that influenced the extraction, including type and volume ofdesorption solvent, rate of sampling, pH value and amount of salt addition wereinvestigated. The results showed that, good linear relationships (r2>0.9976) wereobtained between peak area and concentration of6sulfonylurea herbicides in therange of1.0-20.0μg/L for tribenuron and0.05-20μg/L for rest of the target compoundsunder proper conditions. The detection limits were in the range of0.015-0.044μg/L.The recoveries of surface water, sewage water, sea water samples were in range of97.0-105.8%and89.9-104.5%and89.9%-104.5%respectively, with relative standarddeviation less than7.6%. This method was sensitive, accurate for the detection ofsulfonylurea herbicides in environmental water.