Evaluation of the Effectiveness of Different Acid Digestion on Sediments

The efficiency of four different acids mixtures were evaluated in the determination of total concentration of Pb, Zn, Cu, Cd, Cr and Fe in sediments samples. The acids combination employed included nitric-perchloric acid (NP), aqua regia (NH), sulphuric-hydrogen peroxide (SP) and nitric acid. Sediment samples were taken from five different Lagos lagoon locations; mid lagoon (ML), University of Lagos (UL), Oworonsoki (OW), Ikoyi (IK) and Oko-baba (OB). Validation of the method was performed by using certified reference material IAEA-158 from the International Atomic Energy Agency analytical quality control services, Vienna, Austria. Using Principal component Analysis (PCA), the results revealed that SP acid mixture was efficient for the recovery of Pb, Cd and Cr while NP and NH gave good results and to some extent nitric acid for the extraction of Zn, Fe and Cu; these procedures were recommended for the qualitative determination of Zn, Cu and Fe in sediment. When employing the NP method, the perchloric acid should be added at the later stage of digestion to avoid explosion.