Analysis of THC and an Extended Metabolite Suite from Oral Fluid

Introduction

The method described in this application note achieves high recoveries of THC and an extended suite of common metabolites in oral fluid from Quantisal (Immunalysis) oral fluid collection devices.

Application Note AN815

ISOLUTE^® SLE+ products provide clean, rapid, robust, efficient , high throughput and automatable extraction solutions for a wide range of analytes. This application note describes effective and efficient ISOLUTE SLE+ protocols optimized for sample loading volumes of either 300 μL or 800 μL. The simple sample preparation procedure delivers clean extracts and analyte recoveries greater than 64% with RSDs of <10% for allanalytes.

Figure 1. Structure of Δ9-tetrahydrocannabinol (THC)

Analytes

Δ⁹-tetrahydrocannabinol (THC), cannabigerol, cannabidiol, Δ⁹-tetrahydrocannabivarin (THCV), 11-Hydroxy- Δ⁹-tetrahydrocannabinol (11-OH-THC),
11-nor-9-carboxy- Δ⁹-tetrahydrocannabivarin (THC-V-COOH), 11-nor-9-carboxy-Δ⁹tetrahydrocannabinol (THC-COOH),
11-nor-9-carboxy- Δ⁹tetrahydrocannabinol glucuronide (THC-COOH-glucuronide), Δ⁹-tetrahydrocannabinol glucuronide (THC glucuronide) and Δ⁹-Tetrahydrocannabinolic Acid A (THCA-A)

Sample Preparation Procedure

Column Configuration:
ISOLUTE^® SLE+ 400 μL Sample Volume Columns, Part Number 820-0055-B or ISOLUTE^® SLE+ 1 mL Sample Volume Columns, Part Number 820-0140-C were used. Sample Pre-treatment:
Collect saliva as per packet instructions. When required, remove the paddle from the Quantisal oral fluid collection device and add 10 μL of concentrated formic acid to adjust pH of the sample. Vortex mix thoroughly. Format: ISOLUTE SLE+ 400 μL Supported Liquid Extraction Columns, Part Number 820-0055-B Sample loading:
Load pre-treated sample (300 μL) onto the ISOLUTE SLE+ bed, and apply a pulse of vacuum. Leave for 5 minutes to absorb. Elution 1:
Apply an aliquot of MTBE (750 μL), wait for 5 minutes Elution 2:
Apply a second aliquot of MTBE (750 μL), wait for 5 minutes Elution 3:
Apply a single aliquot of hexane (750 μL) and wait for 5 minutes; apply a pulse of vacuum or positive pressure to complete elution (10 seconds). Post Elution:
Dry the combined eluent in a stream of air or nitrogen using a TurboVap^® LV (1.5 bar at 40 °C) for 40 mins. Reconstitute in 0.1% formic acid in H2O/ACN ((60/40, v/v), 200 μL) and vortex mix thoroughly.

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