MULTIELEMENTAL DETERMINATION OF HEAVY-ELEMENTS IN PLASTICS USING X-RAY-FLUORESCENCE AFTER DESTRUCTION OF THE POLYMER BY MOLTEN SODIUM-HYDROXIDE

In this paper a method is proposed for the multielemental analysis of Sb(III), Ba, Cd, Cr(III), Hg, Pb and As(III) in plastics, using X-ray fluorescence after alkaline decomposition and preconcentration by (co)precipitation. The organic matrix is destroyed by decomposition with sodium hydroxide melted in a silver crucible by the open system technique, using sodium nitrate as auxiliary oxidant. The variables which influence preconcentration are optimized: digestion time, pH, salinity, carrier and sodium diethyldithiocarbamate (DDTC) and sodium rhodizonate (R) as precipitants. The calibration curves were linear up to 200-mu-g of the element present, except for lead (150-mu-g) antimony(III) (100-mu-g) and barium (1000-mu-g). The proposed method has been applied to several different industrial plastics. The procedure is quick and leads to results comparable with those obtained when using a recommended decomposition for each element separately.