Spectrophotometric determination of copper in alloys using naphthazarin

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone: Naph) is proposed as a chro mogenic reagent for the spectrophotometric determination of copper(II). The polynuclear complex has a mole ratio of Cu:Naph = 4:6 in a 50% v/v ethanol /water medium containing 0.1 M ammonium acetate and 1.5% (w/v) sodium dodec yl sulfate. The copper naphthazarin complex shows an absorption maximum at 330 nm with a molar absorptivity of 1.84 x 10(4) l mol(-1) cm(-1). Beer's l aw is obeyed up to 4.5 ppm of copper(II). The method was applied for copper determination in alloy samples with satisfactory results. (C) 2000 Elsevie r Science B.V. All rights reserved.