GF-AAS Determination of Lead in Bean Products with Microwave Assisted Sample Digestion

Bean product sample was digested with HNO3 and H2O2 in the MDS-2002A microwave digestor under prescribed conditions,and the solution in dil. HNO3 was used directly for GF-AAS determination. Ammonium nitrate was added to the sample solution as matrix modifier,and to elevate the ashing temperature as well as to eliminate interference from sodium chloride. Working conditions of the instrument,especially the parameters of working program of the graphite furnace,including time of drying,temperature for ashing and atomization etc.,were studied and optimized. Linear relationship between values of integration of peak heights and concentration of Pb2+ ion was obtained in the range of 2-80 μg·L-1,with detection limit (S/N=3) of 0.1 μg·L-1. The wavelength of analytical spectral line selected was 283.3 nm. Test for recovery was made by standard addition method,and the results obtained were in the range of 94.0%-102.0%.