DETECTION OF SULFUR-DIOXIDE USING A PIEZOELECTRIC QUARTZ-CRYSTAL MICROBALANCE

Sulfur dioxide was detected and determined in air by a piezoelectric q uartz crystal sensor coated with 4-aminoantipyrine/1-hydroxyetil-2-hep tadecenyl imidazol (amine 220) solution (1:1 v/v in chloroform). The a nalytical response curve is linear over the concentration range from 0 .70 to 5.0 ppm of SO2. Good linearities (r = 0.9990, 0.9995 and 0.9968 ) and sensitivities (18.0, 33.4 and 50.7 Hz/ppm) were found, respectiv ely for exposure times of 30, 60 and 90 seconds. The sensor can be use d for more than six months without loss in sensitivity and presented g ood reversibility and reproducibility. Among some possible interferent s tested, only nitrogen dioxide and moisture caused major frequency ch anges.