COMBINED APPLICATION OF INAA AND PIXE FOR STUDYING THE REGIONAL AEROSOL COMPOSITION IN SOUTHERN AFRICA

As part of the SAFARI-92 biomass burning experiment, aerosol collectio ns were carried out with several size-fractionating sampling devices a t a number of sites in Southern Africa. One of the samplers used at al l ground-based sites was a stacked filter unit (SFU). The SFU samples were analyzed by both INAA and PIXE analysis. The present paper gives an intercomparison of the analytical results obtained in order to asse ss the accuracy and to check the quality assurance of the analytical p rocedures. Twenty-one common elements were determined by both INAA and PIXE. Concentrations of 13 elements (i.e., Na, Mg, Al, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Zn and Br) were generally measured with sufficient pre cision in both techniques for performing the intercomparison. The INAA and PIXE data were compared in terms of PIXE/INAA concentration ratio s on a sample by sample basis for the coarse and fine size fraction se parately, The atmospheric concentrations for K, Mn and Fe agreed withi n 5-10%, the agreement between the data for the other common elements was typically better than 15%. Possible explanations for lower than 1. 0 ratios for Cl, Pr and Na are presented. The common elements were cla ssified into groups according to their detectability and sensitivity i n each technique.