Stability of cannabinoids in urine in three storage temperatures

Stability of cannabinoid compounds in urine samples were evaluated using several storage temperatures. Appreciable losses (> 22.4 percent) were observed in some urine samples, after being stored at room temperature for 10 days. Lower losses (8.1 percent) were observed when the urine samples were refrigerated for 4 weeks. The behavior of urine samples depended on the analyzed urine. This could be due to the different stability of the cannabinoids present in each urine sample. Important losses of 8.0 +/- 10.6, 15.8 +/- 4.2, and 19.6 +/- 6.7 percent were found when the urine samples were frozen during 40 days, 1 year, and 3 years, respectively. Average losses (> > 5 percent) can be observed after one day which could mainly be due to the decrease of the solubility of 11-nor-U9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) or adsorption process of cannabinoid molecules to the plastic storage containers.

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				G. Skopp and L. Potsch Stability of 11-Nor-{Delta}9-carboxy-tetrahydrocannabinol Glucuronide in Plasma and Urine Assessed by Liquid Chromatography-Tandem Mass Spectrometry Clin. Chem., February 1, 2002; 48(2): 301 - 306. [Abstract] [Full Text] [PDF]