Published:Journal of Chromatographic Science,
ISSN 0021-9665 Volume
44, Number 7, August 2006, pp.394-398
Evaluation of Solid-Phase Microextraction Desorption
Parameters for Fast GC Analysis of Cocaine in Coca Leaves
Yara Ilias, Stefan Bieri, Philippe Christen,
and Jean-Luc Veuthey
Laboratory of Pharmaceutical Analytical Chemistry, School of Pharmaceutical
Sciences EPGL, University of Geneva, University of Lausanne, 20,
Bd. d’Yvoy, 1211 Geneva 4, Switzerland
By its simplicity and rapidity, solid-phase microextraction
(SPME) appears as an interesting alternative for sample introduction
in fast gas chromatography (fast GC). This combination depends
on numerous parameters affecting the desorption step (i.e., the
release of compounds from the SPME fiber coating to the GC column).
In this study, different liner diameters, injection temperatures,
and gas flow rates are evaluated to accelerate the thermal desorption
process in the injection port. This process is followed with real-time
direct coupling a split/splitless injector to a mass spectrometer
by means of a short capillary. It is shown that an effective,
quantitative, and rapid transfer of cocaine (COC) and cocaethylene
(CE) is performed with a 0.75-mm i.d. liner, at 280°C and
4 mL/min gas flow rate. The 7-µm polydimethylsiloxane (PDMS)
coating is selected for combination with fast GC because the 100-µm
PDMS fiber presents some limitations caused by fiber bleeding.
Finally, the developed SPME-fast GC method is applied to perform
in less than 5 min, the quantitation of COC extracted from coca
leaves by focused microwave-assisted extraction. An amount of
7.6 ± 0.5 mg of COC per gram of dry mass is found, which
is in good agreement with previously published results.
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