Quantitative analysis of pesticide residue based on the dynamic response of a single SnO2 gas sensor

A new rapid detecting method (called dynamic measurements) was reported to detect and distinguish the presence of two pesticide gases and their mixture in the ambient atmosphere. The method employed only a single SnO2-based gas sensor in a rectangular temperature mode to perform the qualitative analysis of pure pesticide gas and a binary gas mixture (acephate and trichlorphon) in air. Experimental results showed that a high selectivity of the sensor was achieved in the range of 250-300 degreesC and modulating frequency 20 mHz. The quantitative analysis between the pure pesticide gas and the mixture was performed by a fast Fourier transformation (FFT). The higher harmonics of the FFT characterized the nonlinear properties of the response at the sensor surface. The amplitudes of the higher harmonics exhibited characteristic changes which depended on the gas concentration and the kinetics of the gas species on the sensor surface. (C) 2003 Elsevier B.V. All rights reserved.