Ultraviolet Photolysis Efficiency Of Phenylurea Herbicides And Their Derivatization Conditions With OPA

Phenylurea herbicides are classes of important pesticide significant to product and income increment in agriculture. Due to its toxicity, non-degradability and bioaccumulation in environment, monitoring residues and controlling their use of phenylureas come to schedule. This paper intended to give technology support to trace residue determination of these herbicides via research of photolysis efficiency of 3 phenylurea herbicides metoxuron, monolinuron and chloroxuron under ultraviolet (UV) in different mobile phases including methanol and water, acetonitrile and water and 12 vegetable matrices, and derivatization of photoproducts and OPA derivatization reagent made of o-phthalaldehyde and 2-mercaptoethylamine. The results were as follows:Statistical analysis of orthogonaltest tables revealed that light wavelength was the key factor effecting UV photolysis efficiency which were significant or very significant higher under UV 254nm than UV 365nm; the UV absorption of mobile phase hindered photolysis of herbicides within it; no addition of 0.5% (v/v) acetone was beneficial to UV photolysis; UV light time was accumulative to photolysis efficiency; the two photolysis temperatures in this experiment had no effect on UV decomposition efficiency of the 3 phenylureas, the same as the interaction between light intensity and UV time. The photolysis velocity ranked chloroxuron>monolinuron>metoxuron.Statistical analysis demonstrated that photolysis efficiency of 3 phenylureas under 254 nm, 1.5 min, 2000μw/cm2 UV light had significant difference between 12 vegetables and were not significant pertinent to UV absorbption. Photolysis efficiency of 3 phenylureas in 12 vegetables matrices under 365nm, 0.5min, 1000μw/cm2 were all higher than in controlled mobile phase, due to the possible containing of photosensitizes such as chlorophyll and related.The photolysis of 3 phenylureas in vegetables matrices could be applied to detection through research of derivatization conditions of 3 phenylurea herbicides and OPA reagent with different flowrates, OPA concentrations and photolysis tube lengths after online UV light, recovery experiments in 3 vegetables and linear ranges.