Introduction
This application note describes the extraction of THC, THCA
and Carboxy-THC from oral fluid matrix collected using the
Quantisall™ (Immunalysis) device, prior to GC/MS analysis.
ISOLUTE® SLE+ Supported Liquid Extraction plates and columns offer an efficient alternative to traditional liquidliquid extraction (LLE) for bioanalytical sample preparation, providing high analyte recoveries, no emulsion formation, and significantly reduced sample preparation.
This application note describes an effective and efficient ISOLUTE SLE+ protocol optimized for 400 μL and 1 mL sample capacity formats. The simple sample preparation procedure delivers clean extracts and analyte recoveries greater than 75% with RSDs lower than 10% for all analytes.
Application Note AN822
Analytes
THC, THCA, THC-COOH and THC-d3, THC-COOH-d3 as internal standards
Sample Preparation Procedure
Sample pre-treatment:
Following collection, add concentrated ammonium hydroxide (15 μL) to each collection device (see additional information).
Format:
ISOLUTE® SLE+ 400 μL sample volume columns, part number 820-0055-B
Sample loading:
Load pre-treated oral fluid (400 μL) onto the column and apply a pulse of vacuum or positive pressure (3–5 seconds) to initiate flow. Allow the sample to absorb for 5 minutes.
Analyte Extraction:
Apply dichloromethane/isopropanol, (95/5, v/v, 1 mL) and allow to flow under gravity for 5 minutes. Apply a further aliquot of DCM/IPA, (95/5, v/v, 1 mL) and allow to flow for another 5 minutes under gravity. Apply vacuum or positive pressure (5–10 seconds) to complete elution.
Format:
ISOLUTE® SLE+ 1 mL sample volume columns, part number 820-0140-C
Sample loading:
Load pre-treated oral fluid (1 mL) onto the column and apply a pulse of vacuum or positive pressure (3–5 seconds) to initiate flow. Allow the sample to absorb for 5 minutes.
Analyte Extraction:
Apply dichloromethane/isopropanol, (95/5, v/v, 2.5 mL) and allow to flow under gravity for 5 minutes. Apply a further aliquot of DCM/IPA, (95/5, v/v, 1 mL) and allow to flow for another 5 minutes under gravity. Apply vacuum or positive pressure (5–10 seconds) to complete elution.
Post Elution & Reconstitution:
Dry the extract in a stream of air or nitrogen using a SPE Dry (40 °C, 20 to 40 L/min) or TurboVap® (1.0 bar at 40 °C for 40 mins).
Upon dryness, reconstitute with 50 μL ethyl acetate and 25 μL MTBSTFA:TBDMCS (99:1, v/v) and vortex for 20 seconds. Transfer to a high recovery glass vial. Place in a heating block set to 70 °C, for 25 minutes. Remove vial from the block and allow cooling.
>> Download the full Application Note as PDF
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