containing 15% of difenoconazole and 15% of propiconazole was obtained from Jiangsu Dongbao Pesticide & Chemical Co. Ltd.(Jiangsu, China). Acetone, n-hexane and methanol were purchased from Merck (Darmstadt, German). Purified water was prepared by a Milli-Q (Millipore, Bedford, MA) water purification system. All other solvents and reagents used in the present study were of HPLC grade or analytical grade.