EVALUATION OF COATING MATERIALS USED ON PIEZOELECTRIC-CRYSTALS FOR THE DETECTION OF DIMETHYL SULFIDE IN LIQUEFIED PETROLEUM GAS

Coated piezoelectric crystals (PZX) were applied to the detection of t he stenching agent dimethyl sulfide (DMS) and its oxidation products, dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO2) in a butane car rier gas stream. Over 39 stationary phase, metal and lipid multibilaye r coating materials have been evaluated for potential gas detection of the target analytes. Good reversibility and fast response times (2 s- 2 min) were exhibited by all coating materials evaluated but sensitivi ty towards DMS was poor (10000 ppm). There is, however, some evidence for the sorption of butane as the coated PZX is introduced into the ga s stream. Both the oxidation products, DMSO and DMSO2, provide positiv e changes in resonant frequency for every coating material evaluated, instead of the expected negative frequency response produced by DMS. T his indicates the removal of previously sorbed species, possibly a but ane adlayer. Reversibility and fast response times (2 s-1 min) were ob served. The DMSO could be determined down to 10 ppm in butane with squ alane as the coating.