Perspectives for Electronic Nose Technology in Green Analytical Chemistry

Electronic nose (eNose) is an analytical methodology for detection and quantification of chemical analytes in vapor phase analogous to mammalian nose. The analogues of olfactory receptor neurons in nasal epithelium, neural network in olfactory bulb and olfactory cortex in mammalian smell sensing are replaced respectively by an array of chemical vapor sensors, signal processing unit and pattern recognition system in an eNose. The eNose technology is extensively developed for detection and identification of a large variety of volatile organic compounds (VOCs) in many application domains such as detection of explosives and narcotics for security, monitoring of hazardous industrial emissions, detection of environmental pollutants, monitoring of food and beverage quality, detection of food freshness/spoilage and health monitoring and disease diagnostics by analysis of body odor. The principles of green chemistry dictate achieving sustainable development through chemistry related activities by minimizing harmful influences on human health and environment. This can be achieved by selecting less hazardous chemicals for input ingredients, optimization of process technology for maximum yield with minimum hazard, minimization of waste generation, automated monitoring and process control. The traditional analytical methods for chemical analysis are largely based on chromatography, mass spectrometry and infrared spectroscopy principles. These methods invariably depend on sample collection, chemical extraction and enrichment methods. 168In addition, these methods are not real time, hence are not appropriate for in-line process monitoring and automated process control applications. The eNoses based on chemical sensors have proven capabilities for real-time detection of volatile organics with detection limits ppb to ppt range. In this chapter we shall briefly describe basics of an eNose system, review status of eNose technology, and present perspectives for their applications in green chemistry activities.