INQUISAL 20936
INSTITUTO DE QUIMICA DE SAN LUIS "DR. ROBERTO ANTONIO OLSINA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Determination of melatonin in wine and plant extracts by capillary electrochromatography with immobilized carboxylic multi-walled carbon nanotubes as stationary phase
Autor/es:
STEGE PW; SOMBRA LL; WIEDMER SK; MESSINA GA; SILVA MF
Lugar:
Valencia
Reunión:
Simposio; 8th International Symposium on Chromatography (ISC 2010); 2010
Resumen:
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The finding of melatonin, the often called hormone of darkness in
plants opens an interesting perspective associated to the plethora of health
benefits related to the moderate consumption of red wine [1]. In the present
work, the implementation of a new method for the determination of melatonin in
complex food matrices by open-tubular capillary electrochromatography (OT-CEC)
with covalently immobilized carboxylic multi-walled carbon nanotubes (c-MWNT)
as stationary phase is demonstrated. Applications of nanoparticles are of
rising interest in separation science, due to their favorable surface-to-volume
ratio as well as their applicability in miniaturization. A stationary phase with
large surface area in combination with an electroosmotic flow-driven system has
great potential in a highly efficient separation system [2].
The investigated samples comprised red and white wine, grape skin, and
plant extracts of Salvia officinalis L. Various extractions methods were investigated, and the optimal
parameters for the extraction were achieved at the following conditions: liquid
extraction with 20 mL of methanol mediated by ultrasonication (200 W) for 7 min.
at 15°C for 0.5 g of grape skin or dried herbs, or 10 mL of wine. The optimal
conditions for the separation were 40 mM sodium tetraborate at pH 9.30,
injection time was at 10 s at 35 mbar, 15 kV, 18ºC (sample and capillary), and
UV detection at 254 nm. The results obtained by OT-CEC were compared with those
by CZE in terms of sensitivity. The results indicated higher resolution, better
separation, and improved sensitivity in CEC, as compared with those obtained by CZE. In addition, highly repetitive
and reproducible results between runs, days, and columns were demonstrated. The
detection limit for melatonin was 0.01 ng mL-1. The method was successfully
applied to the determination of melatonin in red and white wine, grape skin and
plant extracts of Salvia officinalis L.
The feasibility of using c-MWNT immobilized fused-silica capillary through
covalent modification of bare capillaries for the determination of melatonin in
complex food samples has been demonstrated.
