Lowest concentration of an Analyte in a Sample  that can be quantitatively determined with acceptable precision and accuracy (i.e., acceptable Measurement Uncertaint y) under the stated test conditions Threshold Substance:  An exogenous or endogenous Prohibited Substance , Metabolite  or Marker  of a Prohibited Substance  for which the identification and quantitative determination (e.g., concentration, ratio, score) in excess of a pre-determined Decision Limit , or, when applicable, the establishment of an exogenous origin, constitut es an Adverse Analytical Finding .