Detection of brominated by-products using a sensor array based on nanostructured thin films of conducting polymers

The detection of the carcinogenic trihalomethanes (THM) in public water supply systems using low-cost equipment has become an essential feature, since these compounds may be generated as by-products of water-treatment processes. Here we report on a sensor array that extends the concept of an "electronic tongue" to detect small amounts of bromoform, bromodichloromethane and dibromochloromethane, with detection limits as low as 0.02 mg L-1. The sensor array was made up of 10 sensing units, in which nanostructured films of conducting and natural polymers were deposited onto gold interdigitated electrodes. The principle of detection was impedance spectroscopy, with measurements carried out in the range between 1 Hz to 1 MHz. Using data at 1 kHz, at which the electrical response varied considerably by changing the analyte, we demonstrated with principal component analysis (PCA) that samples with the 3 brominated trihalomethanes can be distinguished from each other and for various concentrations.