Arsenic is a naturally occurring element widely distributed in the earth’s crust and a common contaminant of drinking water.

Exposure to arsenic can cause a variety of adverse health effects, including dermal changes, respiratory, cardiovascular, gastrointestinal, genotoxic, mutagenic and carcinogenic effects. Arsenic contamination of drinking water has been reported globally with dangerously high levels present in for example Argentina, Bangladesh, Cambodia, Chile, China, Ghana, Hungary, Inner Mongolia, Japan, Mexico, Nepal, New Zealand, Philippines, Taiwan, the United States and Vietnam.

The World Health Organisation’s recommended maximum arsenic contamination level for drinking water is 10 ppb. A practical issue when addressing arsenic contamination in the real world (as opposed to the academic laboratory) is the large variation in arsenic contamination levels in wells only a few metres apart.

More than 56 million Americans could be drinking tap water containing average levels of arsenic that pose unacceptable cancer risks (source: US NRDC)

Laboratory based analytical procedures have previously been developed to allow detection of low levels of arsenic contamination. The development of reliable electrochemical methods suitable for the development of low cost hand-held test instruments has been hampered by the presence of other contaminants (lead, copper, zinc, iron, antimony, bismuth, selenium, silver and mercury) in real world water samples.

The presence of copper as Cu(II) is the most common source of interference and has to date prevented the development of instruments for use in field testing.

The Oxford invention

Using novel modified glassy carbon electrodes electrochemical techniques have been developed which allow determination of low levels of arsenic contamination even in samples containing high levels of Cu(II) as a co-contaminant.

This invention will enable the development of new low-cost testing devices with high sensitivity that can be directly applied in the field.