Determination of the odor threshold concentrations of iodinated trihalomethanes in drinking water

Iodinated trihalomethanes (ITHMs) have been usually considered the disinfec tion byproducts suspected of causing medicinal odor episodes in treated wat er around the world. The odor threshold concentration (OTC) of mixed ITHMs (bromochloroiodo-, bromodiiodo-, chlorodiiodo-, dibromoiodo-, and dichloroi odomethane) which were previously synthesized - because commercial standard s are not available- were determined by using two sensory techniques: flavo r profile analysis (FPA), performed by an experienced panel trained in iden tifying odors and tastes in water; and gas chromatography coupled with olfa ctometry (GCO). FPA results gave a theoretical OTCs range from 0.1 to 8.9 m ug/L and ITHMs were described as sweet, solvent, and medicinal products. Th e lowest experimental value (OTCexp) obtained from the six ITHMs, 0.03 mug/ L, corresponded to iodoform.