Identification threshold, definition

There are several definitions of threshold. The detection threshold is defined as the lowest stimulus eliciting a sensorial response, even though no identification can be reached. The recognition threshold or identification threshold is the level of stimulus at which the specific stimulus can be identified. The differential threshold or just noticeable difference, is the minimum increase in a stimulus required to detect a difference in the perception. 

An earlier off-odor problem that surfaced was the presence of 4-phenyl-cyclohexene in styrene-butadiene coated paper (Koszinowski et al. 1980). This compound was created by a Diels-Alder condensation reaction involving a molecule of styrene and butadiene and is differentiated by its odor from the isomeric 3 and 1-phenyl-cyclohex-ene compounds which cannot be formed by such a condensation reaction. The recognition threshold of this compound in the headspace over an aqueous solution lies around a concentration of 10 pg/kg (10 ppb). The typical odor of this compound at concentrations of 4-phenyl-cyclohexene in paper over 4 mg/kg (4 ppm) is easily identified. AGC determination in this concentration range is also possible without difficulty and its identification with MS using the relative molecular mass of 158 and one of the retro Diels-Alder decomposition product fragments at m/e = 104 (styrene) and mJe = 54 (butadiene) is definitely possible. 

Section 3.9.5 Technical Performance Measurement. Deseribes the approach and methods to identify, establish, and control key technical parameters (limited to those that are eritieal and/or identified by the customer). Descriptions include the thresholds, methods of measuring and traeking, update frequencies, level of tracking depth, and response time to generate recovery plans and planned profile revisions. Described parameters include identification of related risks. Describes the relationship between the selected parameter and lower-level parameters that must be measured to determine the eritieal parameter achievement value, which is depicted in the form of tiered dependency trees and reflects the tie in to the related system performanee requirement (critical parameter). Includes definition of the correlation of each parameter in the dependeney tree to a specific SBS element. 

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