Identification of 4-bromo-2-chlorophenol as a contaminant responsible for organoleptic taint in melons.

An off-odour, described by the growers as similar to profenofos, occurred in melons in which this pesticide had been used in crop treatment. However, profenofos, O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate, could not be detected in the melons using GC/MS although a component with a shorter retention time was found. Concentration of melon volatiles by steam distillation yielded a product identical to that obtained by hydrolysis of profenofos, identified as 4-bromo-2-chlorophenol. A solution of this compound in water had similar organoleptic properties to that of the contaminated fruits. It was concluded that 4-bromo-2-chlorophenol was responsible for the taint detected in melons.