Evaluation and correction of interference between aluminium, silicon and iron in atomic-absorption spectrophotometry

Inter-element interference in the determination of aluminium, silicon and iron in pyrophosphate solutions has been investigated. The maximum concentrations were 100 p.p.m. of aluminium, 117 p.p.m. of silicon and 50 p.p.m. of iron; the tetrasodium pyrophosphate was 7·5 × 10–3M. In the determination of aluminium, silicate depressed the absorption, while iron did not interfere. Both aluminium and iron enhanced the absorption in the determination of silicon, and in the determination of iron, both aluminium and silicon depressed the absorption. Absorbance data, representing analytical results on some 215 solutions, were fitted to equations containing so-called interference coefficients. With this approach, corrections for inter-element interference are easily made.