Determination of Aluminum in the Presence of Fluoride by Emission Spectroscopy

Abstract

Fluoride greater than 0.1N interfered negatively in the determination of Al by the rotatingdisk-electrode technique. Fluoride interference was eliminated by the addition of H₃BO₃. Aluminum in the 1–100 ppm range was successfully determined in the presence of 0.25N fluoride by making the solutions 2.5% in H₃BO₃. The coefficients of variation among six determinations for solutions containing 10 and 100 ppm Al were 3.0% and 0.9%, respectively. Recovery of known amounts of Al added to fluoride-extracts of soils ranged from 98.4% to 102.2%. The proposed method thus gave acceptable accuracy and precision. The method is simple and rapid since it does not require the removal of fluoride by distillation as H₂SiF₀ nor does it prevent the determination of Si in the same sample.