Development of a novel hand-held toluene gas sensor: Possible use in the prevention and control of sick building syndrome

A novel hand-held toluene gas sensor has been developed. It can be utilized in the control and prevention of sick building syndrome. The sensor is based on the principle that toluene gas reacts with iodine pentoxide producing a brown coloured product, iodine. Iodine pentoxide is impregnated on a filter which is subsequently exposed to toluene gas for a duration of 30 min. The product is detected by measuring the intensity of reflected light at 460 nm using a photo diode and a light emitting diode housed in a hand-held photometer. The degree of colour change is proportional to the concentration of toluene gas. The relative standard deviation for the response (n = 3) to colour change was <10.5% proving this method to be reproducible. By using optimized conditions, we were able to detect 0.05 ppm toluene gas, lower than the 0.07 ppm guideline value for indoor toluene concentration set by World Health Organization. The technique is hardly affected by other common indoor gases, except for a possible interference by benzenoid aromatic hydrocarbons. This sensor is simple, specific, highly sensitive and is suitable for field operations.