A new catalytic kinetic method for determining trace selenium(Ⅳ) was described.Se(Ⅳ) can catalyze the discolouring of 2 (5 Bromo 2 Pyridylazo) 5 diethylaminophenol(5 Br PADAP) by potassium chlorate in hydrochloric acid medium.The detection limit for Se(Ⅳ) is 5.7×10 -5 μg/ml.The linear range of determination is 0～ 0.4μg/25ml Se(Ⅳ).Satisfactory results may be obtained by direct determination of trace Se(Ⅳ) in human hair.
A new method of prepation of 2,5 disubstituted 1,3,4 oxadiazoles from aromatic acids and hydrazine using microwave irradiation in the presence of PPA was described.The results showed that it successful in preparing 2,5 disubstituted 1,3,4 oxadiazoles in 88%～90% yied ander condition of microwave radiation with power 500w,intermittent irradiation within and less than 6 minute.
