Recovery of spiked Δ9-tetrahydrocannabinol in oral fluid from polypropylene containers☆
Introduction
THC is one of the major drugs of concern in police roadside testing programs as well as in workplace drug testing due to its high prevalence around the world. Oral fluid is an increasingly popular matrix to use in drug testing for a number of reasons, including its non-invasive collection, reduced risk of adulteration, a shorter window of detection and thus a more useful indicator of very recent ingestion than urine [1], [2], [3], [4], [5].
Many commercial oral fluid collection devices are available, several of them containing some form of stabilising buffer which dilutes the oral fluid collected. Previous studies have found that these devices often have difficulty collecting consistent volumes of oral fluid and accurate quantification of THC can be challenging [2], [3]. Expectoration is also problematic due to issues such as ‘dry mouth’ and foaming but it is still a viable collection technique, especially since it is the only way to analyse an accurate volume of oral fluid. Hence, it is important to know what interactions THC may have with the containers in which the samples are stored.
Sample containers are commonly made from polypropylene and such containers have been used in recent studies involving oral fluid [6], [7], [8], [9]. Polypropylene was chosen for this study to investigate the adsorptive properties of THC to plastic surfaces when in the oral fluid matrix and also to observe any losses that occur during storage for up to 4 weeks.
Section snippets
Materials
Capped polypropylene centrifuge tubes of 2-mL volume were obtained from Scientific Specialties Inc. (Lodi, CA, USA). THC-free oral fluid was provided from volunteers and used for the study on the day of collection. The absence of THC in collected oral fluid was confirmed by following the sample preparation and analysis procedures described in the following paragraphs.
All solvents and chemicals used were analytical grade or higher. Methanol (MeOH) and ethyl acetate was obtained from RCI Labscan
Method validation
Linearity of the GC–MS method was achieved over the range of 5–1000 ng/mL with a correlation coefficient of 0.9990. The intra- and inter-day precision and accuracy of the method were satisfactory and are summarised in Table 1. The RSD values were 2.52–8.57% and the MRE ranged from 1.38% to 6.48%.
The LOD was determined to be 1 ng/mL. The LOQ was found to be 5 ng/mL. Precision and accuracy at this concentration level was determined to be 3.14% and 9.73% respectively.
Plastic surface and THC recovery
When THC was spiked into 1.5 mL
Discussion
THC is known to be highly lipophilic and poorly water soluble, having a high octanol/water partition coefficient (log P = 6.97) [10]. It is therefore generally accepted that THC can interact with the non-polar plastic material via non-covalent interactions and adsorb to plastic container surfaces. It is also possible that THC degrades readily in oral fluid by way of metabolic action of microorganisms present in the matrix. Both these forces can be overcome by use of buffers containing surfactants
Conclusions
It was demonstrated that THC had the tendency to bind to polypropylene surfaces, leading to poor extraction recovery in neat oral fluid. The recovery of THC is dependent on the oral fluid volume to inner surface area ratio; smaller oral fluid volume in larger containers suffered from a higher loss of THC. Use of Triton® X-100 can significantly increase the THC recovery from polypropylene containers.
References (14)
- et al.
Oral fluid testing for cannabis: on-site OraLine® IV s.a.t. device versus GC/MS
Forensic Sci. Int.
(2006) - et al.
Development and validation of a method for the quantitation of [Delta]9tetrahydrocannabinol in oral fluid by liquid chromatography electrospray-mass-spectrometry
J. Chromatogr. B
(2004) - et al.
Drugs in oral fluid: Part II. Investigation of drugs in drivers
Forensic Sci. Int.
(2005) - et al.
Analysis of cannabis in oral fluid specimens by GC-MS with automatic SPE
Sci. Justice
(2009) - et al.
Analysis of [Delta]9-tetrahydrocannabinol in oral fluid samples using solid-phase extraction and high-performance liquid chromatography-electrospray ionization mass spectrometry
Forensic Sci. Int.
(2005) - et al.
A rapid and sensitive method for the identification of delta-9-tetrahydrocannabinol in oral fluid by liquid chromatography–tandem mass spectrometry
Forensic Sci. Int.
(2012) - et al.
Stability of [Delta]9-tetrahydrocannabinol (THC) in oral fluid using the Quantisal(TM) collection device
Forensic Sci. Int.
(2006)
Cited by (30)
Development and validation of a fit-for-purpose UHPLC-ESI-MS/MS method for the quantitation of cannabinoids in different matrices
2023, Journal of Chromatography B: Analytical Technologies in the Biomedical and Life SciencesPassive exposure to cannabidiol oil does not cause microbiome dysbiosis in larval zebrafish
2021, Current Research in Microbial SciencesDetermination of the alcohol biomarker phosphatidylethanol 16:0/18:1 and 33 compounds from eight different drug classes in whole blood by LC-MS/MS
2021, Journal of Pharmacological and Toxicological MethodsCitation Excerpt :THC is highly lipophilic and may adsorb/bind to glass and plastic containers and to the rubber in container caps (Garrett & Hunt, 1974; Kristoffersen et al., 2018; Roth, Moosmann, & Auwarter, 2013). In some bioanalytical methods Triton-X has been added to increase recovery of THC (Helenius & Simons, 1975; Kristoffersen et al., 2018; Molnar, Lewis, & Fu, 2013; Rangel-Yagui, Pessoa Jr., & Tavares, 2005). In the developed and validated method Triton-X 100 was added before the SLE to increase recovery and reduce possible adsorption of THC to different surfaces.
How do people try to beat drugs test? Effects of synthetic urine, substituted urine, diluted urine, and in vitro urinary adulterants on drugs of abuse testing
2019, Critical Issues in Alcohol and Drugs of Abuse TestingLC-HR-MS/MS standard urine screening approach: Pros and cons of automated on-line extraction by turbulent flow chromatography versus dilute-and-shoot and comparison with established urine precipitation
2017, Journal of Chromatography B: Analytical Technologies in the Biomedical and Life SciencesAdulterants in Urine Drug Testing
2016, Advances in Clinical ChemistryCitation Excerpt :Drug testing programs are also established to service law enforcement authorities [4,5], detect doping in sports [6,7], and facilitate treatment of clinical intoxication, harm minimization, and rehabilitation programs [8–11]. Biological matrices suitable for drug testing purposes include, among others, blood, urine, and oral fluid [12–16]. Urine is considered the most popular testing matrix, as its collection is noninvasive and simple and allows for a relatively wide detection window for most drugs and/or drug metabolites [5,17].
- ☆
This paper is part of the special issue entitled “The 50th Annual Meeting of the International Association of Forensic Toxicologists (TIAFT)”. June 3–8, 2012, Hamamatsu, Japan. Guest edited by Adjunct Professor Einosuke Tanaka and Associate Professor Masaru Terada.