Potassium nitrite reaction with 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid in urine in relation to the drug screening analysis

Recently potassium nitrite has been used as an adulterant to interfere with the analysis of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC- COOH) in urine. A comprehensive study of the THC-COOH and nitrite reaction chemistry and stability under various conditions is presented. Reverse phas e high performance liquid chromatography (HPLC) and negative electrospray m ass spectrometry (ESMS) results are given to substantiate the derived react ion mechanism and properties leading to reaction termination. The addition of potassium carbonate as a buffering agent prior to or following sample vo id as a means of preventing the formation of a nitroso-complexed form of th e 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid is evaluated.