Highly sensitive quantification of pyrethroid insecticide etofenprox in vegetables with high-performance liquid chromatography and fluorescence detection

• A highly sensitive analytical method for etofenprox with HPLC–FLD is presented.
• The method has been applied to six agricultural matrices.
• Sample preparation is based on acetonitrile extraction and versatile SPE clean-up.
• Etofenprox can be determined accurately without matrix interference.
• The HPLC–FLD enables the accurate quantification of a trace of etofenprox.

This paper describes a highly sensitive analytical method using high-performance liquid chromatography and fluorescence detection (HPLC–FLD) capable of quantifying trace amounts of synthetic pyrethroid insecticide etofenprox residue in six vegetable samples: bell pepper, cucumber, eggplant, Japanese mustard spinach, spinach, and tomato. After extraction with acetonitrile, the crude sample extract was cleaned up with a solid-phase extraction cartridge. The matrix interference derived from the tested vegetable samples was evaluated. Quantification was conducted using external calibrators prepared in pure acetonitrile. The limits of quantification for etofenprox in each sample were 1.87–3.87 ng/g. Recoveries obtained by application of the proposed analytical method of vegetable samples spiked at the considerably low levels (5–100 ng/g) were 85–111% with relative standard deviations of less than 12%. The proposed method using the HPLC–FLD was applied for trace analysis of the insecticide residue in vegetable samples.