The on-line monitoring capability of heavy metal ions would
be of interest to the laboratory water market. Heavy metal ions are a cause of
environmental pollution from a number of sources, including lead in petrol,
industrial effluents and leaching of metal ions from the soil into lakes and
rivers by acid rain. The concept of stripping voltammetry is a well understood
and highly respected technique that has been applied for trace level detection
of heavy metal ions, such as zinc, lead, cadmium, copper, mercury, arsenic, etc.
There are commercially available voltammetric systems available, such as
Metrohm, however, they tend to use expensive electrodes such as gold and glassy
carbon, and in certain applications, toxic electrodes, such as mercury. Existing
approaches also fail to detect multiple heavy metal ions at the same time. In
addition to the cost and toxicity issues, the measurements are generally
performed in batch mode.
This technology would avoid the use of mercury by using
bismuth electrodes, which has the advantages of being environmentally friendly
and easier to dispose. It has also been reported to provide equivalent
performance when compared to mercury-based electrodes. The disposable screen
printed electrodes would include reference and auxiliary electrodes. This screen
printed electrode would be integrated into a dedicated flow-through cell and a
given electrode could simultaneously monitor several ions with the one sample,
for example a bismuth electrode could measure zinc, lead, cadmium and copper
from the same sample. The electrochemical route for detecting multiple heavy
metal ions simultaneously in water offers distinct advantages of speed,
miniaturization and sensitivity, thus addressing the urgent needs for field
testing of these species.
Potential Applications
- Laboratory water
- Ultrapure water purification systems
- Water quality monitoring systems
Benefits and Advantages
- Multiple heavy metal ion species can be measured
simultaneously
- Less expensive due to the presence of screen printed
electrodes with integrated auxiliary and reference electrode
- Detection levels in the ppt range (ng/L)
- On-line measurements