title: Method of fast trace microanalysis of the chiral pesticides epoxiconazole and novaluron in soil samples using off-line flow-through extraction and on-column direct large volume injection in reversed-phase high performance liquid chromatography.
abstract: An analytical method combining off-line flow-through extraction of a soil micro-sample (mass around 100 mg, packed into a short HPLC glass column) and direct on-column large-volume injection (LVI up to 1.00 mL) of a methanol-water soil extract onto a conventional C18 RP HPLC column enabled fast (within 3.5 minutes) trace micro-analysis of the relatively new chiral pesticides epoxiconazole (E) and novaluron (N), respectively. Linear calibration curves were evaluated from UV detection (230 nm) data in the range from 0.1 to 5 mg/kg in three most abundant Slovak agricultural soils. LOD (confidence band) at the levels 0.08-0.11 mg/kg and LOQ 0.4-0.6 mg/kg and LOD (S/N = 3) at the levels 0.007-0.018 mg/kg and LOQ (S/N = 10) 0.024-0.060 mg/kg, respectively, of dry soil were achieved. Recovery of pesticides in the overall LVI method including flow-through 130-200 mg soil micro-sample extraction was: for epoxiconazole from 74 to 85% and from 56% to 90% for novaluron with reproducibility within +/- 6% RSD. This fast (30 min) and simple method consists of just three steps which are short column filling with a solid micro-sample; flow-through liquid extraction and direct large-volume injection RP HPLC DAD analysis. The method is prepared for automation and further analysis of enantiomers of both investigated pesticides by achiral-chiral column switching techniques.
authors.affiliation: Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Rybár
authors.forename: Robert
authors.initials: R
authors.lastname: Góra
authors.forename: Milan
authors.initials: M
authors.lastname: Hutta
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D004852:Epoxy Compounds / Q000032:analysis* / Q000737:chemistry; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D010575:Pesticides / Q000032:analysis* / Q000737:chemistry*; D010671:Phenylurea Compounds / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results; D012987:Soil / Q000032:analysis*; D013237:Stereoisomerism; D013997:Time Factors; D014230:Triazoles / Q000032:analysis* / Q000737:chemistry
chemical_list: D004852:Epoxy Compounds; D010575:Pesticides; D010671:Phenylurea Compounds; D012987:Soil; D014230:Triazoles; C109476:epoxiconazole; C471805:novaluron