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.
Golding Fraga
S
S
Laboratory of Clinic Analysis, Association of Youth Cooperation San Miguel, Santa Cruz de Tenerife, Spain.
Díaz-Flores Estévez
J
J
Díaz Romero
C
C
D000327:Adsorption; D002186:Cannabinoids / Q000652:urine*; D003080:Cold Temperature; D004355:Drug Stability; D005615:Freezing; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011126:Polypropylenes; D013048:Specimen Handling / Q000295:instrumentation; D013696:Temperature
D002186:Cannabinoids; D011126:Polypropylenes