Spectrophotometric Determination of Scandium(III) with <i>o</i>-Hydroxyhydroquinonephthalein in Cationic Micellar Media

Abstract

Abstract A spectrophotometric method for determining trace amounts of scandium(III) has been established which makes use of formation of its ternary complex with o-hydroxyhydroquinonephthalein (Qnph) and N-hexadecyl-pyridinium chloride (HPC) as a cationic surfactant at pH 5.4. The molar ratio of the ternary complex among Qnph, scandium(III), and HPC is 3:2:6 in a weakly acidic medium, and its maximum absorbance is at 555 nm against a reagent blank. Beer’s law holds in the concentration range 0–4.5 μg of scandium(III) in a final volume of 10 cm3 at 555 nm. The apparent molar absorptivity is 1.0×105 dm3 mol−1 cm−1 with a Sandell sensitivity of 0.0005 μg cm−2. The coefficient of variation was 0.6% (n=5) for 2.7 μg of scandium(III).