Abstract
A spectrophotometric method is described for the determination of less than 15 μg of boron. To a 50 ml sample solution are added 3 ml of 3 N sulfuric acid and 1.5 ml of 15% hydrofluoric acid. After allowing the solution to stand for 1.5 hours at a temperature above 15°C, 0.2 ml of 1.33 × 10-2 M 1, 10-phenanthroline-iron(II) chelate solution is added, and 1, 10-phenanthroline-iron(II)-BF4-complex is extracted into 10 ml of nitrobenzene. The absorbance is measured at 515 mμ.
More than 400 mg of SO42-, 25 mg of Cl-, 0.5 mg of NO3- or NO2-, 0.01 mg of SCN- and 0.001 mg of ABS- interfere. Common cations do not interfere.
