INVESTIGADORES
STEGE Patricia Wanda
congresos y reuniones científicas
Título:
Determination of illicit drugs in urine samples using carboxylic multi-walled carbon nanotubes as immobilized stationary phase in capillary electrochromatography.
Autor/es:
CECILIA M. PERALTA; VERONICA M. LANARO; LUIS D. MARTINEZ; PATRICA W. STEGE; LORENA L. SOMBRA
Lugar:
Rosario
Reunión:
Congreso; 2º Reunión Internacional de Ciencias Farmacéuticas.; 2012
Resumen:
Introduction
The definition
of doping is the administration of illegal drugs with the intention of altering
the physical performance, in either positive or negative sense [1]. For horse
races is a requirement that the horse should not be declared as a participant
if in their tissues, body fluids or excretions there is any prohibited substances
or its metabolite in higher levels than the normal.
The aim of the
present study was to demonstrate the facility of OT-CEC (Open tubular capillary
electrochromatography) method to separate illicit drugs.
The
determination of abused drugs (carvedilol, procaine,
caffeine, amiloride, ephedrine, clenbuterol and piroxicam) were developed using
capillary electrochromatography (CEC) with a stationary phase of carbon
nanotubes (c-MWNTs) immobilized into a fused-silica capillary [2].
Materials
and methods
A
Beckman P/ACE MDQ instrument (Beckman Instruments, Fullerton, CA, USA) equipped
with a diode array detector and a data handling system comprising an IBM PC and
P/ACE System MDQ Software was used. Carboxylated multi-wall carbon nanotubes (c-MWNTs) have been
immobilized into a fused-silica capillary to form a stationary phase for CEC.
With the purpose of enrichment and sample clean-up we used a simple method as
liquid-liquid extraction. A mixture of Chloroporm/Methanol (90:10) was used as
the extract phase. Then the extract (organic phase) was evaporated to dryness
and the residue was reconstituted with 1 ml of water.
Results
We
have investigated the electrophoretic features of the c-MWNT immobilized
fused-silica capillary by covalent modification of the inner surface of the
capillary. The optimization of the experimental conditions has been accomplished
by the traditional method of one-at-a-time. The peak areas and migration times
were used to evaluate the extraction efficiency, and separation/quantification
efficacy under different experimental conditions. The separation obtained with
the OT-CEC was compared with the one obtained with CZE under the same
electrophoretic conditions. Results indicated good capillary efficiencies and
improved electrophoretic separation. The coating of the capillary with MWCTs
allowed the separation of the analytes with high resolution, with less
band-broadening and without distortion of the baseline. The interactions
between the analytes and the MWCTs resulted in an increase of the migration time.
Moreover and as expected, we could not achieve a good separation of the
analytes with a fused silica capillary. Under the optimum conditions determined
in the current work, seven abuse drugs could be separated in less than 25 min.
This
simple CEC method allowed recognition and quantification of the most common
abused drugs in urine racehorse?s samples.
Conclusions
The
OT-CEC procedure developed here for the simultaneous analysis of seven abused
drugs was precise, reproducible, and sensitive. The advantages of this method
include simplicity with high selectivity, identification and quantification in
the separation of the drugs besides to low cost and efficiency by using MWCTs
as a stationary phase.
We
can conclude that the applicability for monitoring and quantification of abused
drugs used in urine samples for this method has been demonstrated. The
potential of CEC method was shown performing the analysis of urine samples
spiked with the studied compounds after an appropriate extraction procedure.
The positive results obtained proved the applicability of CEC technique in
toxicology analysis.
References
1- World Anti-doping Agency,
www.wada-ama.org.
2-Sombra, L.;
Moliner-Martínez,Y.; Cárdenas, S.; Valcárcel, M.; Electrophoresis 2008,
29, 3850?3857.