Patent ID: 7816143

Claim:
A method for quantifying the amount of 11-nor-Δ 9 -THC carboxylic acid (“THCA”) in an oral fluid sample comprising the steps of: providing an oral fluid sample; ionizing any THCA present in the oral fluid sample under conditions suitable to produce one or more ions detectable by mass spectrometry, wherein said one or more ions detectable by tandem mass spectrometry comprise a THCA parent ion with a mass to charge ratio (m/z) of 620.5 or one or more THCA fragment ions selected from the group of ions with mass to charge ratio (m/z) of 492 and 383; determining the amount of said one or more ions by tandem mass spectrometry; and using the amount of said one or more ions to determine the amount of THCA in the sample.