Journal
JOURNAL OF CHROMATOGRAPHY A
Volume 1245, Issue -, Pages 167-174Publisher
ELSEVIER
DOI: 10.1016/j.chroma.2012.05.017
Keywords
Illicit drugs; Water samples; Cannabinoids; Solid-phase microextraction (SPME); Gas chromatography-mass spectrometry (GC-MS); Derivatization
Funding
- Spanish Ministery of Science and Innovation (Ministerio de Ciencia e Innovacion) [CTQ2009-08377, CTQ2010-18927]
- FPI
- Ramon y Cajal research program
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A new method for the determination of two cannabinoids, Delta 9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-Delta 9-tetrahydrocannabinol (THCCOOH), in wastewater samples is proposed using solid-phase microextraction (SPME) as extraction technique and gas chromatography coupled to mass spectrometry (GC-MS) as determination technique. Several parameters involved in SPME extraction were studied and optimized (time, temperature, volume, pH and ionic strength of sample, and type of fiber). Moreover two derivatization reagents, N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA), were studied in depth, providing MSTFA the best results. The use of internal standard calibration (with their corresponding deuterated analogs) allows avoiding standard addition calibration for the quantification of samples. Under optimal conditions, limits of detection at low nanograms per liter were achieved (1.0 and 2.5 ng L-1 for THC and THCCOOH respectively). Precision (RSD < 15%) and trueness (92-112% relative recovery) were also satisfactory. Analysis of several samples from a wastewater treatment plant (WWTP) shows the presence of cannabinoids at notable concentrations in raw wastewater (12-35 ng L-1 for THC and 50-153 ng L-1 for THCCOOH) and an incomplete removal, which translates into their detection in the receiving river. (c) 2012 Elsevier B.V. All rights reserved.
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