- “B” Confirmation Procedure  for endogenous Threshold Substances  For endogenous Threshold Substances , Adverse Analytical Finding  decisions for the “B” Sample  results shall be based on the confirmed identification (in accordance with the TD IDCR, applicable to Confirmation Procedures  based on chromatography -mass spectrometry) of the Threshold Substance  or its  Metabolite(s)  or Marker(s)  and their quantitative determination in the Sample  at a level exceeding the value of the relevant Threshold  as specified in the TD DL or other applicable Technical Document (s) or Laboratory Guidelines .