Fast Saliva Analysis by GC-MS with Cold EI and Open Probe Fast GC-MS for the Detection of Cannabis Usage

Oneg Elkabets, Tel Aviv University , Tel Aviv, Israel (onegelkabets@mail.tau.ac.il )
Aviv Amirav, Tel Aviv University , Tel Aviv, Israel
Benny Neumark, Tel Aviv University , Tel Aviv, Israel

Introduction

Saliva is a body fluid that is much easier to sample than blood. Thus, saliva analysis for the detection of delta-9 – Tetrahydrocannabinol (THC) can serve as a tool for law enforcers to detect recent cannabis consumption by drivers. However, the analysis has several challenging features including: a) eliminating sample preparation; b) easy sample collection and transportation to the lab; c) selective and sensitive MS methods of saliva analysis; d) fast analysis, preferably in real time.  

Methods

GC-MS with Cold EI is based on interfacing GC and MS with supersonic molecular beams (SMB) along with electron ionization of vibrationally cold sample compounds in the SMB in a contact-free fly-through ion source (hence the name Cold EI). 

Few µl of saliva samples are collected on a thin glass rod directly from donors’ tongues and analyzed using GC-MS with Cold EI equipped with ChromatoProbe device in which the saliva is thermally extracted, or using Open Probe Fast GC-MS (OPFGC-MS).

Saliva analysis features:

1. We can easily detect cannabis consumption with very good sensitivity.


2. We can easily distinguish via retention times, mass spectral fragmentation pattern and library identification between THC and Cannabidiol (CBD). Thus, we can differentiate between the smoking of recreation cannabis cigarettes with THC and the use of medical cannabis with mostly CBD that could be legal.


3. Saliva is collected from the tongues on a thin glass rod that is transported to the lab and analyzed without any sample preparation.


4. Full analysis time for the presence of cannabis is fast, under 10 min with GC-MS with Cold EI (15 min full analysis) and in 1 minute with OPFGC-MS with Cold EI.


5. Drugs are also detectable in saliva. The consumption of Advil capsule resulted in Ibuprofen detection in both blood and saliva, which suggests a correlation between them.

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Short Biography of Presenting Author

Ph.D. student at Prof. Aviv Amirav research lab at Tel Aviv University