Urine pH, container composition, and exposure time influence adsorptive loss of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid.

11-nor-delta9-Tetrahydrocannabinol-9-carboxylic acid (11-nor-delta9-THC-COOH) is the primary cannabinoid present in the urine of individuals who have used marijuana and is the target analyte identified at forensic urinalysis drug testing laboratories. The preparation, storage, transport, and processing of control materials for gas chromatography-mass spectrometric (GC-MS) analysis of human urine specimens is critical to accurate compound identification and quantification. Previous studies have suggested that adsorptive loss of 11-nor-delta9-THC-COOH is influenced by container composition and storage temperature.