Fluoride greater than 0.1<i>N</i> interfered negatively in the determination of Al by the rotating-disk-electrode technique. Fluoride interference was eliminated by the addition of H<sub>3</sub>BO<sub>3</sub>. Aluminum in the 1–100 ppm range was successfully determined in the presence of 0.25<i>N</i> fluoride by making the solutions 2.5% in H<sub>3</sub>BO<sub>3</sub>. 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 H<sub>2</sub>SiF<sub>6</sub> nor does it prevent the determination of Si in the same sample.
L. T. Kurtz, H. L. S. Tandon, and E. C. Marcusiu, "Determination of Aluminum in the Presence of Fluoride by Emission Spectroscopy," Appl. Spectrosc. 22, 283-285 (1968)