Determination of trace lead in iron and steel by electrothermal atomic absorption spectrometry after coprecipitation with yttrium phosphate

The coprecipitation technique using yttrium phosphate as a coprecipitant has been applied to separation of lead from iron matrix. Lead ranging from 0.035 to 1.0 μg could be coprecipitated quantitatively with yttrium phosphate at pH 3.0 from 100mL of approximately 1 mol/L nitric acid solution containing up to 500 mg of iron and 3.0 g of ascorbic acid as a reducing agent; the recovery of iron could be suppressed at less than 0.1%. The collected lead could be determined by electrothermal atomic absorption spectrometry without any interference of yttrium and phosphate after dissolution of the precipitate. In the proposed method, the limits of detection (3σ) and quantification (10σ), which were calculated based on the values obtained from the eight replicate determinations of the blank, were 0.01 μg and 0.035 μg, respectively. The proposed method was applicable to the determination of lead in certified reference material (JSS 591-1) and commercially available iron powder.