[Implementation of an electronic nose for rapid detection of volatile chloralkane and chloroalkene]

An electronic nose, core detector of which was composed of three metal-doped SnO2 gas sensors and a photo ionization detector (PID) as a sensor array, was developed for rapid detection of volatile chloralkane and chloroalkene. A gas recognition model was developed based on test and analysis with nine of pure gas and five of mixtures, and then the electronic nose was applied to several water samples and the validity was evaluated with a gas chromatography. The results revealed that the sensor array responded differently between the chloralkane and chloroalkene. PID was less sensitive to chloralkane, while linearly responded to chloroalkene (R2 > 0.997). Sensor TGS2602 performed sensitive to carbon tetrachloride (CT), trichloromethane (TCM) and 1,2-dichloroethane (1,2-DCA), with a linear response to the former two but a poor linear response to 1,2-DCA. Sensors TGS2600 and TGS2620 were by far more sensitive and linearly (R2 > 0.995) responded to dichloromethane (DCM) and 1,2-DCA. Therefore in the final gas recognition model, PID was used to determine the concentration of chloroalkene, sensor TGS2602 was used to determine CT and TCM, sensor TGS2600 or TGS2620 was used to determine DCM and 1,2-DCA. When applied to gas mixtures, sensor TGS2602 responded less sensitive than the sum of the response to each single component, while other sensors responded equally. The electronic nose showed a determined result linearly correlated to GC (R2 > 0.96) as applied to samples with a mixture of DCM and perchloroethylene.