Analysis Method Study Of Phenylurea Herbicides In Water And Foods By Liquid Chromatography

With the development of society economy, the Chinese people’s diet was covered with alayer of shadow, and all kinds of food safety problems emerged in endlessly. It is important todevelop a food analytical method of sensitive, accurate, practical, nonhazardous. Seven kindsof phenylurea herbicides, such as metoxuron, monuron, monolinuron, metobromuron, diuron,linuron and chloroxuron were analysed, and all of them are harmful to human health.Therefore, establish a sensitive and rapid method to determine phenylurea herbicides inenvironment and food is very necessary. In the chapter one, the literatures of phenylureaherbicides was reviewed. The herbicides’ harm, physical and chemical properties and analysismethods were introduced. Then the future of the detection for pesticide residues wasprospected. Chapter two, a method based on microextraction flask-high performance liquidchromatography was used for determination of phenylurea herbicides in water, such asmonuron, monolinuron, metobromuron and diuron. Phenylurea herbicides were separated onC18column (5μm,250×4.6mm i.d.) employing methanol: water: acetonitrile=60:38:2asmobile phase and determined using UV detector at245nm. The flow rate of mobile phasewas1.0mL/min. N-octyl alcohol was used as extractant to extract from300mL water. Underthe optimal conditions, the regression equations of the four finds of herbicides weredeterminated in blank real samples, and the linearity was good in the range of5~100ng/mLwith the correlation coefficients more than0.998. The spiked recoveries of four herbicidesfrom the water samples were in the range of106%~109%with relative standarddeviations(RSDs) no more than3.40%. The four components’ degradation under irradiationof ultraviolet light and sunlight was investigated. The results show that under254nmirradiation of UV, photolysis efficiency of the four components:metobromuron>monolinuron> monuron>diuron.The photolysis efficiency can reach80%in30minites. However, the sunlight has no effect on photolysis efficiency. Chapter three, amethod was used to determine chloroxuron, monuron and metoxuron in fennel seed by normal-phase liquid chromatography employing dichloromethane:n-hexane:methanol(48:50:2,v:v:v) as the mobile phase. The analyte was extracted from the samples byacetonitrile and cleaned with solid phase column. There was a good linearity in the range of1-100μg/mL and the limit of detection was0.6-1.0μg/g. The recoveries of chloroxuron,monuron and metoxuron were78.9%,83.9%and52.3%, respectively. Chapter four, a methodfor the simultaneous determination of7kinds of phenylurea herbicides (metoxuron, monuron,monolinuron, metobromuron, diuron, linuron and chloroxuron) was established. The sesamepaste sample was treated by subzero-temperature frozen extraction and acetonitrile as asolvent. The effects of salt effect, frozen time and extraction solvent volume were examinedon extraction efficiency. Under the optimal conditions, the recoveries of the target analytewere between90.6%~106.4%and the relative standard deviations (RSDs) were less than7.40%.