A team from the Tomsk Polytechnic University in Russia has developed a mobile device which can rapidly analyse liquids, detecting the presence of hazardous substances like heavy metals.
The team used a method based on polymer optodes. These are very small plastic matrices that can be made sensitive to specific substances by using special reagents. Once sensitised to the target substance, the matrices change colour when the substance is present, and the intensity of the colour change is also dependent on the concentration of the substance.
While engineers can utilise spectrophotometers for chemical analysis currently, the new polymer optode-based device can be used to carry out analysis in-situ, even at low temperatures. It is also much more cost effective.
The core of the device is polymethacrylate sensors, which are transparent pieces of plastic measuring just 3 mm by 3 mm, with a thickness of 1 mm. The pores of matrices serve as receptacles, where various chemical reactions take place.
The sensitised optodes can be plunged into the water sample, or water can be dripped on the sensor to cause colour changes. For example, if water contains silver, the optode will turn purple-red. The method can detect substances even at very low concentrations in water.
Engineers can then load the optode into the analyser device, which reads the optical signals from the optodes, converting it into an electronic RGB signal.
The signal processing indicates to the device the concentration of the target substance, which it then outputs at digital data immediately.
This method allows the detection of almost all metals, organic materials and various pharmacological agents in water.
The team cautioned that the method works only with those substances which can cause colour changes to sensitised optodes, and that not all substances do so. However, given the lack of universal detection methods, and the cost, portability and size advantages over spectrophotometers, it is still a viable water testing method.
The ability to provide rapid analysis in the field will be useful for environmental and related services personnel of industrial enterprises. For example, oil companies can use the device to detect tracers in the drilling fluid.
The team has completed a prototype device, but will now work on a way of using the method for multi-component analysis.