The complexation reaction of scandium with 2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazoquinoxalone (DCHNAQ) in the presence of cetyltrimethylammonium bromide (CTMAB) has been studied. In acetate buffer at pH 3.5, a p-ink violet complex is obtained, with maximum absorption at 722 nm. The molar absorptivity and Sandell sensitivity are calculated to be 3.66 x 104 L mol-1 cm-1 and 1.23 ng/cm2, respectively. The composition of the complex is found to be 1 :1 with logarithmic stability constant of 4.2. Beer`s law is obyed over the concentration range 0.05 – 1.4 µg /ml whereas Ringbom optimum concentration range is 0.1 – 1.3 µg /ml. The proposed method was successfully used to determine trace amounts of scandium in geological ore samples and compared statistically with the results obtained using atomic absorption spectra.

J. Saudi Chem.Soc., 4, 129–136 (2000).