The Confirmation Procedure  shall be able to discriminate between Analytes  of closely related structures ; - Limit of Identification  (LOI): When the analyses of Non-Threshold Substances  are based on chromatographic -mass spectrometric techniques, the Laboratory  shall determine the  lowest  concentration at which each Non-Threshold Substance  or its representative Metabolite (s) or Marker (s), for which a Reference Material  is available, is identified at no more than  5% false negative rate  (in compliance with the TD IDCR or other applicable Technical Document , Technical Letter  or Laboratory Guidelines ).