14 research outputs found
Determination of Trace Bismuth by Under-Potential Deposition-Stripping Voltammetry at Mesoporous Platinum Microelectrodes: Application to Pharmaceutical Products
A methodology for the determination of bismuth,
based on under-potential deposition-stripping voltammetry
(UPD-SV), was investigated. It makes use of mesoporous
platinum microelectrodes (Pt-MEs) prepared by a liquid
crystal templating technique. The mesoporous microelectrodes,
which are characterised by a very high surface area,
allowed the accumulation of relatively large amounts of
bismuth at under-potential without saturation of the electrode
surface. Calibration plots for quantification of bismuth
at micromolar levels were constructed by using the charge
involved in either the anodic or cathodic peak recoded by
cyclic voltammetry that ensued the accumulation of bismuth
at the electrode surface. During the anodic scan, the oxidation
of metallic bismuth occurred; the cathodic scan involved
irreversibly adsorbed bismuth species, which are
retained on to the electrode surface. The reproducibility of
the proposed UPD-SV procedure (which was within 5 %)
was assured by the application to the Pt-MEs of a suitable
potential waveform, properly designed to avoid memory
effect due to the irreversibly deposited bismuth. The latter
phenomenon along with UPD allowed to overcome interference
due to copper, which is normally observed when
quantification of bismuth is performed by anodic stripping
voltammetry at solid electrodes involving bulk metal deposits.
The usefulness of the proposed method for the determination
of bismuth in real samples was demonstrated by the
analysis of a tablet of a pharmaceutical preparation, which is
used for curing ulcers