Part I: A comparative study of bismuth-modified screen-printed electrodes for lead detection.
Lead determination was carried out in the frame of the European Union project Biocop (www.biocop.org) using a bismuth-modified screen-printed electrode (Bi-SPE) and the stripping analysis technique. In order to choose a sensitive Bi-SPE for lead detection, an analytical comparative study of electrodes modified by Bi using "in situ", "ex situ" and "bulk" procedures was carried out. On the basis of the results obtained, we confirmed that the "in situ" procedure resulted in better analytical performances with respect to not only "ex situ" but also to "Bi(2)O(3) bulk" modified electrodes, allowing for a linear range of lead ion concentration from 0.5 to 100 μg L(-1) and a detection limit of 0.15 μg L(-1). We demonstrated that, before the Bi film deposition, an oxidative electrochemical pre-treatment of the working electrode could be useful because it eliminates traces of lead in the graphite-ink, as shown with stripping measurements. It also improves the electrochemical performance of the electrodes as demonstrated with Electrochemical Impedance Spectroscopy (EIS) measurements. The influence of different analytical parameters, such as the electrolyte solution composition (acetate buffer, chloridric acid, nitric acid, perchloric acid) and the ionic strength was investigated in order to evaluate how to treat the sample before the analysis. The morphology of prepared "in situ" Bi-SPEs was also characterized by Atomic Force Microscopy (AFM). Finally, the Bi-SPEs were used to determine the concentration of lead ions in tap and commercial water samples obtaining satisfactory values of the recovery percentage (81% and 98%).
Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Rome, Italy.
Josefina Calvo
JC
Quintana
Fabiana
F
Arduini
Aziz
A
Amine
Francesco
F
Punzo
Giovanni Li
GL
Destri
Chiara
C
Bianchini
Daniela
D
Zane
Antonella
A
Curulli
Giuseppe
G
Palleschi
Danila
D
Moscone
D001729:Bismuth / Q000032:analysis* / Q000737:chemistry; D058266:Dielectric Spectroscopy / Q000379:methods* / Q000592:standards; D004566:Electrodes / Q000592:standards; D007854:Lead / Q000032:analysis* / Q000737:chemistry; D018625:Microscopy, Atomic Force / Q000379:methods; D014873:Water Pollutants / Q000032:analysis
D014873:Water Pollutants; D007854:Lead; D001729:Bismuth