Dispersive liquid–liquid microextraction prior to field-amplified sample injection for the sensitive analysis of 3,4-methylenedioxymethamphetamine, phencyclidine and lysergic acid diethylamide by capillary electrophoresis in human urine

▸ Separation of MDMA, PCP and LSD by capillary electrophoresis in less than 8min. ▸ FASI provides high sensitivity for the detection of MDMA, PCP and LSD in urine. ▸ DLLME yields low conductivity extracts from urine compatible with FASI, with high efficiency. ▸ LODs of 1.00, 4.50, and 4.40ng/mL for...

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Bibliographic Details
Published in:Journal of Chromatography A 2012-12, Vol.1267, p.189-197
Main Authors: Airado-Rodríguez, Diego, Cruces-Blanco, Carmen, García-Campaña, Ana M.
Format: Article
Language:English
Subjects:
Capillary electrophoresis
capillary zone electrophoresis
chromatography
Dispersive liquid–liquid microextraction
drugs
Drugs of abuse
electrical conductivity
electrolytes
experimental design
Field-amplified sample injection
humans
liquid-phase microextraction
response surface methodology
solvents
temperature
Urine
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Summary:▸ Separation of MDMA, PCP and LSD by capillary electrophoresis in less than 8min. ▸ FASI provides high sensitivity for the detection of MDMA, PCP and LSD in urine. ▸ DLLME yields low conductivity extracts from urine compatible with FASI, with high efficiency. ▸ LODs of 1.00, 4.50, and 4.40ng/mL for MDMA, PCP and LSD, with satisfactory precision. ▸ Utility of DLLME/FASI-CZE-UV for forensic analysis has been demonstrated. A novel capillary zone electrophoresis (CZE) with ultraviolet detection method has been developed and validated for the analysis of 3,4-methylenedioxymethamphetamine (MDMA), lysergic acid diethylamide (LSD) and phencyclidine (PCP) in human urine. The separation of these three analytes has been achieved in less than 8min in a 72-cm effective length capillary with 50-μm internal diameter. 100mM NaH2PO4/Na2HPO4, pH 6.0 has been employed as running buffer, and the separation has been carried out at temperature and voltage of 20°C, and 25kV, respectively. The three drugs have been detected at 205nm. Field amplified sample injection (FASI) has been employed for on-line sample preconcentration. FASI basically consists in a mismatch between the electric conductivity of the sample and that of the running buffer and it is achieved by electrokinetically injecting the sample diluted in a solvent of lower conductivity than that of the carrier electrolyte. Ultrapure water resulted to be the better sample solvent to reach the greatest enhancement factor. Injection voltage and time have been optimized to 5kV and 20s, respectively. The irreproducibility associated to electrokinetic injection has been correcting by using tetracaine as internal standard. Dispersive liquid–liquid microextraction (DLLME) has been employed as sample treatment using experimental design and response surface methodology for the optimization of critical variables. Linear responses were found for MDMA, PCP and LSD in presence of urine matrix between 10.0 and 100ng/mL approximately, and LODs of 1.00, 4.50, and 4.40ng/mL were calculated for MDMA, PCP and LSD, respectively. The method has been successfully applied to the analysis of the three drugs of interest in human urine with satisfactory recovery percentages.
ISSN:0021-9673
DOI:10.1016/j.chroma.2012.10.011