Abstract: Two microwave digestion procedures were developed for unleaded gasoline. Microwave plasma torch atomic emission spectrometry(MPT-AES) was used to determine trace lead in unleaded gasoline after being digested. Optimal conditions (analytical wavelength, microwave power, flow rate of carrier gas for the trace lead determination, flow rate of supporting gas, flow rate of oxygen shielding gas and acid concentrations) were chosen. The effects of concommitant elements on determination of lead were studied. The detection limit for lead was 25 ng/mL, the linear range was 0.05-100 μg/mL. The relative standard deviation for determination of unleaded gasoline samples was less than 4 9%, relative error was less than 3.7%. Standard addition recoveries were all between 93.3%-104.0%. The determination results with microwave digestion were in agreement with those obtained with conventional method. The proposed method is simple, rapid, accurate, and with less possibility to be contaminated by the environment, and of great applied value.

Key words: Microwave digestion, Microwave plasma torch atomic emission spectrometry(MPT-AES), Unleaded gasoline, Trace lead