The odor detection threshold is the lowest concentration of a certain odor compound that is perceivable by the human sense of smell. The thresholds of a chemical compound is determined in part by its shape, polarity, partial charges and molecular mass. The olfactory mechanisms responsible for a compound's different detection threshold is not well understood, as such, these thresholds cannot yet be accurately predicted. Rather, they must be measured through extensive tests using human subjects in laboratory settings.
Optical isomers can have different detections thresholds since their conformations may cause them to be less perceivable for the human nose. It is only in recent years that such compounds were separated on gas chromatographs.
Famous quotes containing the words odor and/or threshold:
“The spring over there takes you by the throat, the flowers blooming by the thousands over white walls. If you strolled around for an hour in the hills surrounding my town, you would return with the odor of honey in your clothes.”
—Albert Camus (1913–1960)
“I am admonished in many ways that time is pushing me inexorably along. I am approaching the threshold of age; in 1977 I shall be 142. This is no time to be flitting about the earth. I must cease from the activities proper to youth and begin to take on the dignities and gravities and inertia proper to that season of honorable senility which is on its way.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)