Determination of Ianthanum, Cerium and Scandium in Aluminum Alloys by ICP-AES

For samples with mass fraction of silicon ≤ 2%, 0.100 0 g was dissolved with 10 mL of HCl (1+1) solution and few drops of hydrogen peroxide. For samples with mass fraction of silicon >2%, 0.100 0 g was dissolved first in 10 mL of 200 g·L^-1 NaOH solution, and then acidified with 15 mL of HCl (1+1) solution. La 408.671 nm, Ce 413.765 nm and Sc 361.384 nm were selected as analysis lines. Matrix effect of aluminum was elimited using matrix matching method. The linearity ranges of La, Ce and Sc were 1.0-10.0 mg·L^-1, with detection limits (3s) of 3.5, 6.1, 3.1 μg·L^-1. The proposed method was applied to the analysis of alluminum alloy samples with mass fraction of La, Ce and Sc within 0.005 0%-0.500%, giving the sum of contents of La, Ce and Sc in consistency with the determination result of total rare elements obtained by the spectrophotometry with tribromoarsenazo as color reagent. RSDs (n=11) were less than 6.0%.