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High-performance liquid chromatographic determination of pesticides in tomatoes using laboratory-made NH2and C18solid-phase extraction materials

Journal of Chromatography A
Publication Date
DOI: 10.1016/j.chroma.2004.09.043
  • Sample Preparation
  • Solid-Phase Extraction
  • Multiclass Pesticide Analysis
  • Tomatoes
  • Method Validation
  • Law


Abstract A method for high-performance liquid chromatographic (HPLC) multiresidue determination of six pesticides in tomatoes was developed and validated. Silica-based C 18 (octadecyl) and NH 2 (aminopropyl) solid-phase extraction (SPE) sorbents, made in our laboratory, were used for sample preparation. The SPE materials were obtained by thermal immobilization of appropriate polysiloxanes onto 40 μm silica surfaces and were used in sample preparation for multiresidue analysis of the following pesticides: tebuthiuron and diuron (urea herbicides), simazine, atrazine and ametryn (triazines herbicides) and benomyl (benzimidazol fungicide). The results were compared with similar commercial materials. Reversed-phase high-performance liquid chromatography (RP-HPLC) using a Purospher RP-18 5 μm column and ACN: 0.01% aqueous NH 4OH, pH 8.4 (35:65, v/v) as mobile phase, at 0.7 ml min −1, with 235 nm UV detection, was used for separation and quantification of the pesticides. Method validation was performed at three fortification levels (100, 200, 1000 μg l −1). Limits of detection and quantification show that the methods developed can be used to detect the pesticides in concentrations below the maximum residue levels (MRL) established by the Codex Alimentarius, USA, European Union and Brazilian legislations. The results showed that aminopropyl materials have a better performance than the octadecyl sorbents. Laboratory-made materials give results similar to commercial sorbents, with recoveries and precisions in agreement with directives for method validation in residue analysis.

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