title: Determination of neonicotinoid insecticides in environmental samples by micellar electrokinetic chromatography using solid-phase treatments.
abstract: A sensitive and reliable method based on MEKC has been developed and validated for trace determination of neonicotinoid insecticides (thiamethoxam, acetamiprid, and imidacloprid) and the metabolite 6-chloronicotinic acid in water and soil matrices. Optimum separation of the neonicotinoid insecticides was obtained on a 58 cm long capillary (75 μm id) using as the running electrolyte 40 mM SDS, 5 mM borate (pH 10.4), and 5% (v/v) methanol at a temperature of 25°C, a voltage of 25 kV and with hydrodynamic injection (10 s). The analysis time was less than 7 min. Prior to MEKC determination, the samples were purified and enriched by carrying out extraction-preconcentration steps. For aqueous samples, off-line SPE with a sorptive material such as Strata-X (polymeric hydrophobic sorbent) and octadecylsilane (C₁₈) was carried out to clean up and preconcentrate the insecticides. However, for soil samples, matrix solid-phase dispersion (MSPD) was applied with C₁₈ used as the dispersant. Good linearity, accuracy, and precision were obtained and the detection limits were in the range between 0.01 and 0.07 μg mL⁻¹ for river water and 0.17 and 0.37 μg g⁻¹ for soil samples. Recovery levels reached greater than 92% for all of the assayed neonicotinoids in river water samples with Strata-X. In soil matrices, the best recoveries (63-99%) were obtained with MSPD.
authors.affiliation: Department of Chemistry, Faculty of Agronomy, University of Zulia, Maracaibo, Venezuela.
authors.forename: Gretty
authors.initials: G
authors.lastname: Ettiene
authors.forename: Roberto
authors.initials: R
authors.lastname: Bauza
authors.forename: María R
authors.initials: MR
authors.lastname: Plata
authors.forename: Ana M
authors.initials: AM
authors.lastname: Contento
authors.forename: Angel
authors.initials: A
authors.lastname: Ríos
mesh_terms: D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D007093:Imidazoles / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D007306:Insecticides / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D057230:Limit of Detection; D016014:Linear Models; D000073943:Neonicotinoids; D009539:Nicotinic Acids / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D009574:Nitro Compounds / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D010078:Oxazines / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D011725:Pyridines / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D015203:Reproducibility of Results; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D052616:Solid Phase Extraction / Q000379:methods*; D000077922:Thiamethoxam; D013844:Thiazoles / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009539:Nicotinic Acids; D009574:Nitro Compounds; D010078:Oxazines; D011725:Pyridines; D012989:Soil Pollutants; D013844:Thiazoles; D014874:Water Pollutants, Chemical; C082359:imidacloprid; C464485:acetamiprid; D000077922:Thiamethoxam; C035953:6-chloronicotinic acid