title: Combining solid-phase microextraction and on-line preconcentration-capillary electrophoresis for sensitive analysis of pesticides in foods.
abstract: The combined use of solid-phase microextraction (SPME) and different on-line preconcentration strategies for ultrasensitive capillary electrophoresis-ultraviolet (CE-UV) analysis of five pesticides in a single run is investigated. Normal stacking mode (NSM), field-enhanced sample injection (FESI), and stacking with matrix removal (SWMR) are explored to increase the sensitivity of the CE-UV analysis of a selected group of pesticides (cyprodinil, cyromazine, pyrifenox, pirimicarb, and pyrimethanil). It could be observed that reverse polarity-stacking with matrix removal (RP-SWMR) provided the best results in terms of sensitivity (enhancement was up to 272-fold compared with normal injection). The separation buffer consisted of 0.4 mM cetyltrimethylammonium chloride (CTAC), 0.4 M acetic acid at pH 4 containing 5% v / v 2-propanol. This approach was then combined with SPME to determine the pesticides in water, apple, and orange juice. The combination of both preconcentration procedures allowed the determination of these pesticides at concentrations down to 2.5 microg / L in water and 3.1 microg / L in juices (i.e., levels well below the maximum residue limits allowed for these compounds). To our knowledge, this is the first report showing the great possibilities of the combined use of SPME, on-line sample preconcentration, and CE for pesticide analysis.
authors.affiliation: Department of Analytical Chemistry, Nutrition and Food Science, University of La Laguna, La Laguna, Tenerife, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Hernández-Borges
authors.affiliation: Department of Food Analysis, Institute of Industrial Fermentations (CSIC), Madrid, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cifuentes
authors.affiliation: Department of Analytical Chemistry, Nutrition and Food Science, University of La Laguna, La Laguna, Tenerife, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: García-Montelongo
authors.affiliation: Department of Analytical Chemistry, Nutrition and Food Science, University of La Laguna, La Laguna, Tenerife, Spain.
authors.forename: Miguel Á
authors.initials: MÁ
authors.lastname: Rodríguez-Delgado
mesh_terms: D002219:Carbamates / Q000032:analysis / Q000302:isolation & purification; D019075:Electrophoresis, Capillary / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D005638:Fruit / Q000737:chemistry; D010091:Oximes / Q000032:analysis; D010575:Pesticides / Q000032:analysis* / Q000302:isolation & purification; D011725:Pyridines / Q000032:analysis; D011743:Pyrimidines / Q000032:analysis / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet; D014227:Triazines / Q000032:analysis / Q000302:isolation & purification
chemical_list: D002219:Carbamates; D010091:Oximes; D010575:Pesticides; D011725:Pyridines; D011743:Pyrimidines; D014227:Triazines; C011994:pirimicarb; C108338:cyprodinil; C108337:pyrimethanil; C501582:pyrifenox; C028704:cyromazine
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