title: On-line preconcentration and chiral separation of propiconazole by cyclodextrin-modified micellar electrokinetic chromatography.
abstract: A method for the chiral separation of propiconazole using cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) with hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD) as chiral selector is reported. The use of a mixture of 30 mM HP-gamma-CD, 50mM SDS, methanol-acetonitrile 10%:5% (v/v) in 25 mM phosphate buffer solution was able to separate two enantiomeric pairs of propiconazole. Stacking- and sweeping-CD-MEKC under neutral pH (pH 7) and under acidic condition (pH 3.0) were used as two on-line preconcentration methods to increase detection sensitivity of propiconazole. Good repeatabilities in the migration time, peak area and peak height were obtained in terms of relative standard deviation (RSD). A sensitivity enhancement factor of 100-fold was achieved using sweeping-CD-MEKC at acidic pH. This is the first report on the separation of two pairs of propiconazole enantiomers and all the enantiomers of fenbuconazole and tebuconazole using sweeping-CD-MEKC. The limit of detection (S/N=3) for the three triazole fungicides ranged from 0.09 to 0.1 microg/mL, which is well below the maximum residue limits (MRL) set by Codex Alimentarius Commission (CAC). Combination of solid-phase extraction (SPE) pretreatment and sweeping-CD-MEKC procedure was applied to the determination of selected triazole fungicides in grapes samples spiked at concentration 10-40 times lower than the MRL established by the CAC. The average recoveries of the selected fungicides in spiked grapes samples were good, ranging from 73% to 109% with RSD of 9-12% (n=3).
authors.affiliation: Separation Science Research Group, Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. wanaini@kimia.fs.utm.my
authors.forename: Wan Aini
authors.initials: WA
authors.lastname: Wan Ibrahim
authors.forename: Dadan
authors.initials: D
authors.lastname: Hermawan
authors.forename: Mohd Marsin
authors.initials: MM
authors.lastname: Sanagi
mesh_terms: D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D003505:Cyclodextrins / Q000737:chemistry*; D005659:Fungicides, Industrial / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D009570:Nitriles / Q000032:analysis; D009862:Online Systems; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods; D013237:Stereoisomerism; D014230:Triazoles / Q000032:analysis* / Q000737:chemistry; D027843:Vitis / Q000737:chemistry / Q000506:poisoning*; D047408:gamma-Cyclodextrins / Q000737:chemistry*
chemical_list: D003505:Cyclodextrins; D005659:Fungicides, Industrial; D009570:Nitriles; D014230:Triazoles; D047408:gamma-Cyclodextrins; C479659:hydroxypropyl-gamma-cyclodextrin; C045950:propiconazole; D012967:Sodium Dodecyl Sulfate; C087114:tebuconazole; C504383:fenbuconazole