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.

Trace analysis of environmental matrices by large-volume injection and liquid chromatography–mass spectrometry

“…Although most of the applications listed in Table 2 involve the direct injection of aqueous samples, several indicate that extracts of vegetables [20] or soil [30][31][32] are analyzed by SC-LVI ( Table 2). The final organic solvent-based extracts were diluted with water and the injected samples ranged in composition from 25% organic solvent (acetonitrile or methanol)/75% up to 70% organic solvent/30% water and then analyzed by SC-LVI.…”

“…There are a limited number of cases where SC-LVI is used for the analysis of pesticides extracted using organic solvents such as methanol from soil [31,32] and vegetables [20]. In each of these cases, the methanol extracts first are diluted to water to give sample compositions ranging from 25:75 to 70:30 (methanol:water).…”

On‐line flow‐through extraction–preconcentration‐large volume injection‐RP LC for trace determination of pyrethroids in Slovak soil

“…As far as we know only one article was published 21 years ago by Ruijten et al [21] and the concept needs thorough re-evaluation in the light of our previous results [3,4,22,23], recent developments in columnswitching HPLC, soil column chromatography, e.g. [24], soil sample pretreatment techniques, e.g.…”

“…In the present work we focused to solve the problems of HPLC trace analysis of selected group of pyrethroids in soil micro-samples following our previous guidelines [3,4].…”

LC-MS/MS method for simultaneous determination of myclobutanil, hexaconazole, diniconazole, epoxiconazole and tetraconazole enantiomers in soil and earthworms

“…Previous studies also showed that (+)-tebuconazole was accumulated from soil to earthworms with a biota to soil accumulation factor (BASF) of 1.64, whereas (-)-tebuconazole did not accumulate in earthworms [11]. Several studies have focused on the determination of triazoles in soil [12][13][14][15]. Furthermore, a number of technologies, such as high-performance liquid chromatography (HPLC) [16][17][18][19][20], gas chromatography, capillary electrophoresis (CE) [21][22][23], supercritical fluid chromatography (SFC) [24], thin layer chromatography (TLC), simulated moving bed chromatography (SMBC), countercurrent chromatography and microtechnology have been introduced in enantiomers' analysis [25,26].…”