Mercury displacement in the determination of sulfur dioxide with a piezoelectric crystal detector

A piezoelectric crystal detector utilizing a mercury displacement reaction is described for the detection and determination of sulfur dioxide. The mercury vapor produced by bubbling the sulfur dioxide through a mercurous nitrate solution is detected by a gold-coated piezoelectric crystal due to the formation of a mercury amalgam. This detector exhibits good sensitivity and selectivity and can be used in the ppb and ppm concentration ranges of sulfur dioxide.