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Title

Focused microwave-assisted extraction combined with solid-phase microextraction and gas chromatography-mass spectrometry for the selective analysis of cocaine from coca leaves
Authors
Bieri, Stefan
Ilias, Yara
Bicchi, Carlo
Veuthey, Jean-Luc
Christen, Philippe
Published in Journal of Chromatography. A. 2006, vol. 1112, no. 1-2, p. 127-32
Abstract An effective combination of focused microwave-assisted extraction (FMAE) with solid-phase microextraction (SPME) prior to gas chromatography (GC) is described for the selective extraction and quantitative analysis of cocaine from coca leaves (Erythroxylum coca). This approach required switching from an organic extraction solvent to an aqueous medium more compatible with SPME liquid sampling. SPME was performed in the direct immersion mode with a universal 100 microm polydimethylsiloxane (PDMS) coated fibre. Parameters influencing this extraction step, such as solution pH, sampling time and temperature are discussed. Furthermore, the overall extraction process takes into account the stability of cocaine in alkaline aqueous solutions at different temperatures. Cocaine degradation rate was determined by capillary electrophoresis using the short end injection procedure. In the selected extraction conditions, less than 5% of cocaine was degraded after 60 min. From a qualitative point of view, a significant gain in selectivity was obtained with the incorporation of SPME in the extraction procedure. As a consequence of SPME clean-up, shorter columns could be used and analysis time was reduced to 6 min compared to 35 min with conventional GC. Quantitative results led to a cocaine content of 0.70 +/- 0.04% in dry leaves (RSD <5%) which agreed with previous investigations.
Keywords Chemical Fractionation/instrumentation/methods — Coca/chemistry — Cocaine/analysis — Gas Chromatography-Mass Spectrometry — Microwaves — Plant Leaves/chemistry
Identifiers
PMID: 16384568
Full text
Article (Published version) (292 Kb) - document accessible for UNIGE members only Limited access to UNIGE
Structures
Faculté des sciences / Section des sciences pharmaceutiques
Citation
(ISO format) 		BIERI, Stefan et al. Focused microwave-assisted extraction combined with solid-phase microextraction and gas chromatography-mass spectrometry for the selective analysis of cocaine from coca leaves. In: Journal of Chromatography. A, 2006, vol. 1112, n° 1-2, p. 127-32. https://archive-ouverte.unige.ch/unige:6658

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Deposited on : 2010-05-21

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