DIFFERENTIAL PULSE POLAROGRAPHIC DETERMINATION OF ARSENIC IN BITUMINOUS COAL
Differential pulse polarography was employed for the determination of arsenic in bituminous coal from Figueiras, Parana, Brazil. The dried coal sample was crushed to -100 mesh, ashed, and treated with reducing reagents in acidic media. The arsine generated was collected and selectively oxidized to Al +3 using an absorbing solution of 0.1 mol.L -1 [tris(hydroxymethyl) aminomethane] ( TRIS) and 0. 002 mol.L -1 silver nitrate. A solution of TRIS and hydrochloric acid, pH -1, was used as supporting electrolyte for differential pulse polarographic determination of Al+3 in the concentration range 0.05 -0.60 μglmL. The average arsenic concentration found was 69.0 ± 2.6 mg.kg -1 and was in agreement with the spectrophotometric method using silver-diethyldithiocarbamate-pyridine.