Identification of a pharmaceutical packaging off-odor using solid phase microextraction gas chromatography/mass spectrometry

The use of a solid phase microextraction (SPME) sampling technique, in conj unction with gas chromatography/ mass spectrometry (GC/MS) analysis, to ide ntify an off-odor in a heat-stressed pharmaceutical packaging material is d escribed. The ability of the commercially available polydimethylsiloxane (P DMS) coated microfiber to concentrate a trace volatile compound of interest enabled identification of the odor compound of interest. Despite being pre sent at levels that defied detection using conventional headspace sampling techniques, ethyl-2-mercaptoacetate was determined to be the compound respo nsible for the offending odor. Formation of the thioester resulted from an unanticipated reaction (either esterification or transesterification) betwe en a common residual solvent (ethanol), present in a commonly used pharmace utical tablet dispersant, and low-level amounts of reactants or synthetic i ntermediates of an FDA-approved polyvinyl chloride (PVC)-resin thermal stab ilizing agent. (C) 2001 Elsevier Science B.V. All rights reserved.