Identification of odorous sulfur containing organic compounds in building products on gypsum basis

Gypsum is widely used in building products, e.g. as drywall, stucco or constituent in mortar because it is easy to handle and it is assigned creating a good indoor air atmosphere. Odor analysis of a gypsum product with a sulfurous off-odor by means of gas chromatography - olfactometry (GCO) compared to two unobtrusive commercial gypsum products revealed various sulfur containing organic compounds as odorants at very small concentrations not allowing structural identification. Gypsum deposits naturally contain small amounts of sulfur which during production can react with organic compounds, e.g. from beater additives, to form organic sulfur compounds. Odor analysis of a gypsum raw material and a semi-processed product thereof from a Chinese deposit with a very intense sulfurous off-odor revealed high concentrations of organic sulfur compounds identical in analytical, chromatographic and sensory properties to the unidentified sulfur compounds of the commercial products and therefore suitable for structural identification of those unknowns. In this way a number of sulfides, disulfides, thiols and aromatic sulfur compounds could be identified contributing to the odor of gypsum products.