Analysis of Contact Traces of Cannabis by In-Tube Solid-Phase Microextraction Coupled to Nanoliquid Chromatography

Abstract

Because of its inherent qualities, in-tube solid-phase microextraction (IT-SPME) coupled on-line to nanoliquid chromatography (nanoLC) can be a very powerful tool to address the new challenges of analytical laboratories such as the analysis of traces of complex samples. This is the case of the detection of contact traces of drugs, especially cannabis. The main difficulties encountered in the analysis of traces of cannabis plants on surfaces are the low amount of sample available (typically < 1 mg), the complexity of the matrix, and the low percentages of cannabinoic compounds in the samples. In this work, a procedure is described for the detection of residues of cannabis on different surfaces based on the responses obtained by IT-SPME coupled to nanoLC with UV diode array detection (DAD) for the cannabinoids Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN); the proposed conditions can also be applied for quantitative purposes through the measurement of the percentage of THC, the most abundant cannabinoid in plants. The method is based on collecting the suspected drug samples with cotton swabs, followed by the extraction of the target compounds by ultrasound assisted extraction. The extracts are then separated and processed by IT-SPME-nanoLC. The proposed approach has been applied to the detection of traces of cannabis in different kind of items (plastic bags, office paper, aluminum foil, cotton cloths, and hand skin). Sample amounts as low as 0.08 mg have been collected and analysed for THC. The selectivity and effect of the storage conditions on the levels of THC have also been evaluated. The percentages of THC in the samples typically ranged from 0.6% to 2.8%, which means that amounts of this compound as low as 1–2 µg were adequately detected and quantified. For the first time, the reliability of IT-SPME-nanoLC for the analysis of complex matrices such as cannabis plant extracts has been demonstrated.

A review on the recent advances in HPLC, UHPLC and UPLC analyses of naturally occurring cannabinoids (2010–2019)

“…. Another example is the use of nanoliquid chromatography coupled with in‐tube solid‐phase microextraction for the analysis of contact traces of Cannabis containing CBD ( 3 ), CBN ( 8 ) and THC ( 12 ) obtained from plastic bags, office papers, aluminium foil, cotton cloths and hand skin, applying UV‐DAD detection …”

Bioanalytical HPLC Applications of In-Tube Solid Phase Microextraction: A Two-Decade Overview

“…Typical examples of WCOT polar columns are 14% cyanopropylphenyl methyl polysiloxane [ 33 , 34 , 35 ], polyethylene glycol column [ 34 , 36 , 37 , 38 , 39 , 40 , 41 ], and 100% nitroterephthalic-modified polyethylene glycol [ 37 ]. Typical examples of nonpolar WCOT columns are polydimethyl siloxane [ 38 , 39 , 40 , 42 ], 95% polydimethyl siloxane, 5% polyphenyl siloxane [ 36 , 38 , 39 , 40 , 43 , 44 , 45 ], 35% diphenyl-65% polydimethylsiloxane [ 45 ], 20% diphenyl-80% polydimethylsiloxane [ 45 ], and (50%-phenyl)-methylpolysiloxane [ 46 ]. Ionic liquid phase commercial SLB-IL100 (Supelco, Bellefonte, PA, USA) has been also evaluated for in-tube SPME [ 47 ].…”

Exploring New Extractive Phases for In-Tube Solid Phase Microextraction Coupled to Miniaturized Liquid Chromatography

“…This is because relatively large sample volumes can be loaded into the extractive capillary for on-line analyte enrichment overcoming the lack of sensitivity derived from the fact that only low volumes of the samples can be injected in miniaturized LC systems. The utility of IT-SPME in Cap-LC has been demonstrated through a wide variety of applications mainly in the environmental and biomedical fields [4][5][6][7] and, very recently, IT-SPME has been coupled to Nano-LC [8,9]. Substantial progress in the area can be expected through the development of new sorbents for the improved extraction of a wide variety of analytes and matrices.…”