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

Iodinated trihalomethanes (ITHMs) have been usually considered the disinfection byproducts suspected of causing medicinal odor episodes in treated water around the world. The odor threshold concentration (OTC) of mixed ITHMs (bromochloroiodo-, bromodiiodo-, chlorodiiodo-, dibromoiodo-, and dichloroiodomethane) which were previously synthesized - because commercial standards are not available- were determined by using two sensory techniques: flavor profile analysis (FPA), performed by an experienced panel trained in identifying odors and tastes in water; and gas chromatography coupled with olfactometry (GCO). FPA results gave a theoretical OTCs range from 0.1 to 8.9 mug/L and ITHMs were described as sweet, solvent, and medicinal products. The lowest experimental value (OTCexp) obtained from the six ITHMs, 0.03 mug/L, corresponded to iodoform.