Stability of 11 prevalent synthetic cannabinoids in authentic neat oral fluid samples: glass versus polypropylene containers at different temperatures

Abstract

Although synthetic cannabinoids have been intensively investigated in recent years and oral fluid testing is becoming increasingly popular in suspected driving under the influence of drugs cases, only scarce data on their stability in authentic neat oral fluid (nOF) samples are yet available. However, especially for these new psychoactive drugs, investigations focusing on stability issues are necessary as inappropriate storage conditions may lead to considerable analytical problems. Since it has been shown for Δ(9) -tetrahydrocannabinol that adsorption to plastic surfaces may lead to considerable drug loss, we aimed to evaluate whether adsorption also has to be taken into account for synthetic cannabinoids in nOF samples. In this paper, the results of investigations on the recovery of 11 prevalent synthetic cannabinoids from authentic nOF samples stored over 72 h in RapidEASE (high quality borosilicate glass) and Sciteck Saliva Split Collector (polypropylene) tubes at 4 and 25 °C are presented. Our findings clearly demonstrate that lipophilic synthetic cannabinoids present in nOF samples adsorb to the surface of polypropylene containers when stored at room temperature, leading to considerable drug loss. Hence, when using polypropylene tubes, samples should be shipped cooled in order to avoid a substantial decrease of the analyte concentration during transportation.

Keywords: container; glass; neat oral fluid; polypropylene; stability; synthetic cannabinoids; ‘Spice’.