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Use of an ionic liquid‐based surfactant as pseudostationary phase in the analysis of carbamates by micellar electrokinetic chromatography

Tejada‐Casado, Carmen, Moreno‐González, David, García‐Campaña, Ana M., Olmo‐Iruela, Monsalud
Electrophoresis 2015 v.36 no.6 pp. 955-961
aldicarb, asulam, benomyl, carbendazim, carbofuran, cationic surfactants, electrophoresis, ethiofencarb, hydrodynamics, ionic liquids, liquid-phase microextraction, micellar electrokinetic capillary chromatography, pH, propoxur, temperature, tomato juice
The applicability of an ionic liquid‐based cationic surfactant 1‐dodecyl‐3‐methyl‐imidazolium tetrafluoroborate (C₁₂MImBF₄) as pseudostationary phase in MEKC has been evaluated for the analysis of 11 carbamate pesticides (promecarb, carbofuran, metolcarb, fenobucarb, aldicarb, propoxur, asulam, benomyl, carbendazim, ethiofencarb, isoprocarb) in juice samples. Under optimum conditions (separation buffer, 35 mM NaHCO₃and 20 mM C₁₂MImBF₄, pH 9.0; capillary temperature 25°C; voltage –22 kV) the analysis was carried out in less than 12 min, using hydrodynamic injection (50 mbar for 7.5 s) and detection at 200 nm. For the extraction of these CRBs from juice samples, a dispersive liquid–liquid microextraction (DLLME) procedure has been proposed, by optimization of variables affecting the efficiency of the extraction. Following this treatment, sample throughput was approximately 12 samples per hour, obtaining a preconcentration factor of 20. Matrix‐matched calibration curves were established using tomato juice as representative matrix (from 5 to 250 μg/L for CBZ, BY, PX, CF, FEN, ETH, ISP, and 25–250 μg/L for ASL, ALD, PRC, MTL), obtaining quantification limits ranging from 1 to 18 μg/L and recoveries from 70 to 96%, with RSDs lower than 9%.