A combination of single-drop microextraction and open tubular capillary electrochromatography with carbon nanotubes as stationary phase for the determination of low concentration of illicit drugs in horse urine

PATRICIA W. STEGE; ALICIA V. LAPIERRE; LUIS D. MARTINEZ; GERMÁN A. MESSINA; LORENA L. SOMBRA

TALANTA

ELSEVIER SCIENCE BV

Lugar: Seattle; Año: 2011 p. 278 - 283

0039-9140

In this study we developed an interesting alternative to HPLC–mass spectrometry for the quantificationof seven important drugs of abuse in racehorses. The procedure proposed in this work is a combinationof single-drop microextraction (SDME) and an open tubular capillary electrochromatography (OT-CEC)using multi-wall carbon nanotubes (MWCTs) immobilized into a fused-silica capillary as a stationaryphase. The SDME showed to be a powerful tool for extraction/preconcentration of the seven drugs analyzedin the study, showing an enrichment factor between 38- and 102-fold depending on the drug. Wehave investigated the electrophoretic features of MWCTs immobilized fused-silica capillary by covalentmodification of the inner surface of the capillary. The results show a good run-to-run, day-to-day andcapillary-to-capillary reproducibility of the method. Compared with the capillary zone electrophoresis(CZE), the coating of the capillary allowed the separation of the analytes with high resolution, with lessband-broadening and without distortion of the baseline. The interactions between the analytes and theMWCTs resulted in an increased migration time and probably this was the reason of the front tailing effect.The results showed a good capillary efficiencies and an improved of the electrophoretic separation.