SELECTIVE DETERMINATION OF TRACES OF COPPER BY ADSORPTIVE ACCUMULATION OF COPPER(I) BENZOTRIAZOLATE, TRANSIENT AMALGAMATION AND ANODIC-STRIPPING VOLTAMMETRY
Vb. Nascimento et Igr. Gutz, SELECTIVE DETERMINATION OF TRACES OF COPPER BY ADSORPTIVE ACCUMULATION OF COPPER(I) BENZOTRIAZOLATE, TRANSIENT AMALGAMATION AND ANODIC-STRIPPING VOLTAMMETRY, Electrochimica acta, 43(23), 1998, pp. 3423-3429
Anodic stripping voltammetry with adsorptive accumulation of amalgam f
orming metals is proposed and demonstrated for the determination of tr
aces of copper ions in, the presence of benzotriazole, HBTA (an excell
ent corrosion inhibitor for copper). The accumulation of the metal ion
s is accomplished, as customary, by adsorption on the mercury electrod
e of a coordination compound with a suitable ligand. Specifically, cop
per(II) is reduced to copper(I) and accumulated as the Cu(I)BTA comple
x on a hanging mercury drop electrode at 0.0 V vs SCE, under convectio
n. Subsequently, copper(I) is reduced to the amalgam by applying a pot
ential step to -0.4 V during 15 s or less. Finally, the potential is s
canned in the positive direction and the differential pulse anodic pea
k of the re-oxidation of Cu(Hg) to Cu(I)BTA is recorded. A 2 min accum
ulation period provides a detection limit of 3 x 10(-9) M and an analy
tical curve linear up to 8 x 10(-7) M. Accumulation for 10 min (or mor
e) lowers the detection limit to 8 x 10(-10) M (or lower). The new mod
e opens alternatives to improve the selectivity of cathodic stripping
methods involving amalgam forming metals, and to reconsider ligands th
at give rise to unsatisfactory cathodic stripping peaks, such as HBTA.
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