Sensor speeds water analysis

Long-term continuous monitoring of groundwater where contaminants are present or suspected could be streamlined with a technology developed at the US Department of Energy’s Oak Ridge National Laboratory.

The new system – described in Analytical Chemistry – is said to combine a membrane tube and an ion mobility analysis system (analyser), creating a single procedure for in-situ monitoring of chlorinated hydrocarbons in water.

This obviates the need for laboratory-based technologies for the analysis of water contaminants, which are time consuming, labour intensive and expensive.

‘Our technology represents a low-cost, yet highly accurate way to monitor contaminants in water and air,’ said Jun Xu, the lead researcher for the project.

The proprietary system, called membrane-extraction ion mobility spectrometry, is a single compact device able to detect aqueous tetrachloroethylene and tricholoroethylene concentrations as low as 75 micrograms per litre with a monitoring duty cycle of three minutes.

Xu noted that this technology would reduce the cost of long-term monitoring of contaminants in groundwater by up to 80 per cent.

‘Based on this technology, a field-deployable sensor can be made and you would no longer need to have someone take a groundwater sample from a well and ship it to a laboratory for testing,’ Xu said. ‘The ORNL sensor does all three of these tasks in one step and very quickly, saving money.’

According to ORNL, the sensor can also be configured to monitor well, tap or river water or other water suspected of having an undesirable or possibly illegal level of contamination.

Similarly, additional membranes with different properties can be installed to enable collection of a wider variety of contaminants.