Preconcentration of bismuth(III) and copper(II) by solid-phase extraction and subsequent determination by differential pulse polarography

A differential pulse polarographic method is proposed for the trace determi nation of bismuth and copper from large volumes of aqueous samples after ad sorption of their 1-(2-thiazolylazo)-2-naphthol complexes onto microcrystal line naphthalene in the pH ranges of 7.2-9.0 and 4.0-7.8, respectively. Bis muth and copper are desorbed from microcrystalline naphthalene with 9 mL 1M HCI, Well-defined peaks are obtained at E-p = -0.09 and -0.20 V versus a s aturated calomel electrode, in an HCI-isoquinoline medium as the supporting electrolyte, for bismuth and copper, respectively. Bismuth is reduced reve rsibly with a 3-electron change, whereas copper is reduced irreversibly und er these conditions. The detection limits are 55 ng/mL for bismuth and 91 n g/mL for copper, Linearity is maintained in the concentration ranges of 0.1 8-13.5 and 0.30-17.3 mug/mL for bismuth and copper, respectively, with corr esponding correlation coefficients of 0.9996 and 0.9885. The relative stand ard deviations are 1.0% for bismuth at 2.0 mug/mL and 1.4% for copper at 5. 0 mug/mL. Various parameters were optimized to develop conditions for the d etermination of these metal ions in various samples.