Determination of boron in steel by anion-exchange separation and ICP-AES

Abstract

The determination of boron in steel was carried out by ICP-AES combined with anion-exchange separation. About 0.2 g of a steel sample was weighed in a quartz beaker and dissolved with a mixture of 2 cm3 of nitric acid, 1.5 cm3 of phosphoric acid and 4 cm3 of water by heating on a hot plate. Most of the nitric acid was evaporated off and the sample solution was transferred into a separatory funnel with 10 cm3 of 0.1 mol dm−3 nitric acid and water. About 3 g of iron(III) hydroxide oxide was dissolved in a mixture of 10 cm3 of hydrofluoric acid, 1 cm3 of 30% hydrogen peroxide and 50 cm3 of water by heating on a hot plate and added to the above sample solution. The sample solution was diluted to about 100 cm3 with water, allowed to stand for 1 h and then loaded onto an anion-exchange resin Bio-Rad AG1 column preconditioned by a fluoride solution. The iron in the sample solution passed through the column, while the boron was adsorbed as BF4− on the column and recovered with 6.5 mol dm−3 nitric acid. The effluent, containing boron, was treated with phosphoric, perchloric and nitric acids and diluted to 25 cm3 with water to be subjected to ICP-AES at 249.77 nm. The proposed method was successfully applied to the determination of boron in a steel-certified reference material, JSS 174-5, provided by the Japan Iron and Steel Federation. The detection limit was found to be 1.3 μg g−1 boron in steel.