Table 1

Cut-off concentrations in whole blood and oral fluid

SubstanceCut-off in whole blood (ng/mL)Cut-off in oral fluid (ng/mL)
Alcohol (ethanol)0.01 g/dL0.01 g/dL
7-aminoclonazepam10*3.1*
Alprazolam3†1.1‡
Amphetamine41†740‡
Benzoylecgonine–95*
Buprenorphine0.37†12§
Clonazepam1.3†0.23¶
Cocaine24†498¶
Codeine100‡680‡
Diazepam57†2.2‡
Flunitrazepam1.6†0.23‡
Meprobamate1091**1000§
Methadone25†54¶
Methamphetamine45†930‡
Morphine9†86‡
Nitrazepam17†1.5‡
Nordiazepam108†5.9¶
Oxazepam172†45‡
Phenazepam1.8†0.5§
Phenobarbital4640**20§
Tetrahydrocannabinol1.3†39‡
Zolpidem31†8.5‡
Zopiclone12†30‡

  • *Cut-off concentrations in blood and oral fluid from the DRUID project.11

  • †Legislative limit in Norway from February 2012 or 2016.

  • ‡Equivalent cut-off concentrations in oral fluid described by Bogstrand and Gjerde.7

  • §Analytical cut-off concentrations in oral fluid.6

  • ¶Equivalent cut-off concentrations in oral fluid calculated using formulae determined by the DRUID project.11

  • **Analytical cut-off concentrations in blood.