Detection and determination of 11-nor-9-carboxy-Delta 9-carboxylic acid (THCA), which is a metabolite of principal psychoactive constituent of cannabis plant, is necessary to confirm cannabis use from urine. Sample pretreatment method suitable for handling low volume and low concentration sample has been desired for the determination because THCA concentration in urine is in ppb level.
In this note, MonoSpin, which provides high recovery even from sample of less than 100 ?L, was used for the sample pretreatment, and the purified solution was injected into LC/MS/MS system. The results showed good linearity, recovery, and reproducibility.