Optimal use of instrumental neutron and photon activation analyses for multielement determinations in sewage sludges

A combination of instrumental neutron-activation analysis (INAA) and instrumental photon-activation analysis (IPAA) methods has been developed for multielement determinations in a variety of sludges and fertilizers. The precision and accuracy of both methods have been evaluated by analyzing replicate samples, NBS standard reference materials and an interlaboratory intercomparison sewage sludge sample. The concentration ranges of up to 50 elements in raw and chemical sludges, sludge-based fertilizers and other organic and inorganic fertilizers are reported. From the agricultural point of view essential elements such as Na, Mg, Cl, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Mo, Sn and I are generally present in large amounts in sewage sludges. In addition, sludges and sludge-based fertilizers have been found to contain elements of toxicological and environmental concern. This group includes As, Br, Sr, Ag, Cd, Sb, Te, Ba, Hg, Tl, Pb and Bi. The IPAA method has the potential for determining two more important elements, namely N and F, whose concentration levels are often sought. (T.G.)