Successive determinations of platinum(II) and selenium(IV) with 1,4-dibromo-2,3-diaminonaphthalene in aqueous micellar solutions

Highly sensitive successive determinations for Pt ^II and Se ^IV ions have been developed based upon reactions with 1,4-dibromo-2,3-diaminonaphthalene (Br ₂ DAN), which forms a near-infrared (NIR) absorbing complex (ε = 1.2 × 10 ⁵ 1 mol ^-1 cm ^-1 at 800 nm) and an emissive complex (ex. 386 nm, em. 604 nm) for Pt ^II and Se ^IV ions, respectively, in acidic aqueous micellar solutions. In the presence of a cationic surfactant, cetyltrimethylammonium chloride, the detection limits for Pt ^II and Se ^IV ions are 1.2 ng ml ^-1 (3σ) and 0.98 ng ml ^-1 (S/N = 3), respectively. Hydrobromic acid plays a key role to enhance the color development of the NIR-absorbing Pt ^II complex. The influences of Cu ^II and Zn ^II ions at the normal human serum levels are readily tolerated, and interference from Fe ^I3II ion at 35 μmol 1 ^-1 is circumvented by the addition of 50 μmol 1 ^-1 of polyaminocarboxylates, such as EDTA.