Trace determination of sulfonylurea herbicides in water and grape samples by capillary zone electrophoresis using large volume sample stacking.

Department of Analytical Chemistry, University of Granada, Campus Fuentenueva, s/n, 18071 Granada, Spain.
Analytical and Bioanalytical Chemistry (Impact Factor: 3.66). 05/2010; 397(6):2593-601. DOI: 10.1007/s00216-010-3812-7
Source: PubMed

ABSTRACT A sensitive and reliable method using capillary zone electrophoresis with UV-diode array detection has been developed and validated for trace determination of residues of sulfonylurea herbicides in environmental water samples and grapes from different origins. The analytes included are triasulfuron, rimsulfuron, flazasulfuron, metsulfuron-methyl, and chlorsulfuron. Optimum separation has been achieved on a 48.5-cm x 50-microm (effective length 40 cm) bubble cell capillary using 90 mM ammonium acetate buffer, pH 4.8, by applying a voltage of 20 kV at 25 degrees C and using p-aminobenzoic acid as the internal standard. In order to increase sensitivity, large volume sample stacking with polarity switching has been applied as on-line preconcentration methodology. For water samples, a solid-phase extraction (SPE) procedure based on the use of Oasis HLB cartridges was applied for off-line preconcentration and cleanup. For grape samples, the SPE procedure was achieved with C(18) sorbent, after extraction of the compounds with MeOH:H(2)O (1:1) by sonication. The limits of detection for the studied compounds were between 0.04 and 0.12 microg/L for water samples and 0.97 and 8.30 microg/kg in the case of grape samples, lower in all cases than the maximum residue limits permitted by the EU for this kind of food. The developed methodology has demonstrated its suitability for the monitoring of these residues in environmental water and grape samples with high sensitivity, precision, and satisfactory recoveries.

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    ABSTRACT: Capillary electrophoresis (CE) has been recognized as a highly attractive separation technique for determining agrochemical residues in agricultural produces and environmental matrices due to its extremely high column efficiency, rapid analysis, and less reagent consumption. However, a small sample size and a short optical path length make the low concentration samples detected with an ultraviolet (UV) detector difficult or even impossible without sample preconcentration. The on-line concentrating techniques promise to extremely increase sample size without the changes of CE instrument and make the detection of agrochemical residues possible by CE. This review describes these on-line preconcentration techniques and comments their applications in the determination of agrochemical residues.
    Journal of Liquid Chromatography &amp Related Technologies 06/2014; 37(10). · 0.64 Impact Factor
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    ABSTRACT: Sulfonylureas (SUs) are one of the most widely used herbicides to control weeds in crops. Herein, capillary electrophoresis (CE) was used to determine four sulfonylureas in natural waters, namely chlorsulfuron (CS), iodosulfuron methyl (IM), metsulfuron methyl (MSM) and mesosulfuron methyl (MSS). First of all, a bare silica capillary was chosen with 10mM of 1-butyl-3-methylimidazolium tetrafluoroborate (bminBF4) as electrophoretic buffer (pH 9.6) containing 2mgL(-1) of surfactant-coated single-wall carbon nanotubes (SC-SWCNTs). A dramatic deviation in migration times was observed. Therefore, a poly(diallyldimethylammonium) chloride (PDADMAC) statically coated cationic capillary was used to improve repeatability and to alter the selectivity of the separation. The electroosmotic flow (EOF) measurement revealed that the SC-SWCNTs were strongly adsorbed at the surface of the PDADMAC coating even in the absence of the surfactant-coated nanotubes in the electrolyte buffer. Consequently, a stable strong cathodic EOF and excellent repeatabilities were obtained with relative standard deviations (RSDs) on migration times and on corrected peak areas below 0.9 and 1.5%, respectively. The separation of the SUs was conducted in only 6min. No regeneration of the coating between analyses was necessary, and high peak efficiencies up to 173,000 theoretical plates were obtained. The bi-layer coating was subsequently used to analyze sulfonylureas in tap water, in several mineral waters as well as in underground waters spiked with SUs and directly injected into the CE capillary.
    Journal of Chromatography A 09/2014; · 4.26 Impact Factor
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    ABSTRACT: Voltammetric behavior of triasulfuron (TS), sulfonylurea herbicide, was investigated using mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and hanging mercury drop electrode (HMDE). It was found that TS provided one well-developed reduction peak and the highest current response was recorded in Britton–Robinson buffer of pH 3 (m-AgSAE) and 2.5 (HMDE), respectively. Differential-pulse voltammetry (DPV) with optimized working parameters was applied for analysis of model solutions containing TS with good sensitivity (LD(m-AgSAE) = 6.4 × 10−8 mol L−1 and LD(HMDE) = 2.7 × 10−9 mol L−1, respectively). Proposed method was successfully applied in analysis of herbicide preparation and river water.
    Electrochimica Acta 12/2013; 113:1. · 4.09 Impact Factor


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May 30, 2014