A simple method for evaluation of the total concentration of Cd, Cr, Cu, Pb and Zn in sediments from the São Gonçalo channel in Pelotas, RS, Brazil

This study evaluated the total concentrations of Cd, Cr, Cu, Pb and Zn in sediments samples from the Sao Goncalo channel, Patos-Mirim lagoon complex, RS state, Southern Brazil during 2013 autumn, winter and spring, and 2014 summer. Ultrasound-assisted extraction method was employed to extract metals from the sediment samples. The sample powder was mixed with HNO3 and HF in an ultrasonic bath during 60 minutes at 25 oC. The limits of detection were 0.002; 0.026; 0.83; 0.386 and 0.44 mg kg-1 for Cd, Cr, Cu, Pb and Zn, respectively. The accuracy of the method was confirmed by analysis of two sediment certified reference materials and its precision was determined by the values of relative standard deviation lower than 9.1%. The concentrations obtained ranged from 0.11 to 0.58 mg kg-1 for Cd; 14.7 to 38.4 mg kg-1 for Cr; 3.9 to 102.0 mg kg-1 for Cu; 1.6 to 3.11 mg kg-1 for Pb; and 29.3 to 126 mg kg-1 for Zn. These values did not exceed the probable effect levels (PEL). Simplicity, low cost and high efficiency are some of the qualities of the method, making it adequate for routine analysis.