Evaluation of Analytical Methods for Lead (Pb) (USEPA 3051) and Zinc (Zn) (HR-CS AAS) in Sediments

A variety of analytical techniques may be used to determine the concentration of metals in sediment, such as methods numbers 3050, 3051 and 3052 of the United States Environmental Protection Agency (USEPA). The reading of samples after digestion can be carried out by high-resolution continuous source atomic absorption spectrometry (HR-CS AAS), and background correction technique can be applied by the squared minimums algorithm (LSBC). This study aims to test the digestion times (5000 s, for first digestion and 1800 s for second digestion) using the 3051 method, to determine the Pb level and correct possible spectral interferences in the determination of Zn in sediment samples by LSBC. Sampling was conducted in the Palmeiras River, a tributary of the River Tubarão, SC, Brazil. Samples were digested in microwave ovens and readings in HR-CS AAS with flaming atomization. Pb readings were found for the samples digested in number one and two digestions, and a Zn reading was found in only the second digestion, with and without LSBC. Minor variations in temperature were observed and higher Pb recovery rates were found in the second digestion. The use of LSBC in Zn readings made it possible to obtain more accurate values.