Development of Copper(i) Iodide Detection Systems for Volatile Organic Compounds

The spontaneous emission of volatile organic compounds (VOCs) from common household items presents physiological hazards when inhaled over long periods of time. As a result, developing economical and reliable methods of detecting VOCs in hermetically-sealed enclosures, such as those employed in transportation, are important in ensuring the safety of passengers. In this study, copper(I) iodide (CuI) was utilized due to its labile coordination with nucleophilic ligands, photoluminescent emission in the UV-Vis region, and low toxicity. Essentially, the photophysical properties permit visual detection of environmental VOCs. Two detection systems were developed and analyzed for their effectiveness. First, CuI nanoparticles were synthesized and embedded into polyvinyl chloride (PVC) films. Secondly, thin CuI films were cast over glass cover slips with an evaporative technique. CuI-embedded PVC films exhibited inconsistencies in emissive data when exposed to nucleophilic ligands, most probably due to the nucleophile inhibitory effects resulting from the polymer matrix. CuI films cast upon glass cover slips demonstrated an increase in the number of coordinating nucleophiles and greater emissive consistency. Therefore, CuI films casted upon glass cover slips have proven to be a more appropriate detector substrate for future limit of detection studies. Introduction VOCs can pose many adverse shortand long-term health effects and are characteristically higher in concentration indoors. According to the EPA, VOCs are commonly emitted from paints and lacquers, paint strippers, cleaning supplies, building materials and furnishings, office equipment, and fuels. Consequently, the health effects range from eyes, nose, and throat irritation to central nervous system damage. The severity of damage depends on the type of VOC. Because the amount of VOCs number in the hundreds, many different methods of detection are required to ensure safer environmental conditions. Recently, interest has increased in the development of VOC detectors. VOC monitoring methods developed thus far tend to be either overly expensive or require offsite analysis, making them unrealistic for implementation in hermetically-sealed enclosures such as airplane and space shuttle passenger cabins. For example, adsorption of VOCs onto a catalyst sensor could be quantified using thermogravimetric analysis, a technique requiring costly instrumentation and unrealistic to install in transportation vehicles. In another study, VOCs in ambient air was monitored using GC-FID and GC-MS complementary techniques. While detection and quantification are excellent with this technique, this too is unrealistic given the cost of mass spectrometry. Lastly, a study by Endo et al described the detection of VOCs through the swelling of an elastomer matrix and measuring the changes in the wavelength of Bragg diffracted light. The techniques described thus far represent difficulties in achieving a good balance between a quantifiable detection system while