Evaluation of the Persistence of Linalool and Estragole in Maize Grains via Headspace Solid-Phase Microextraction and Gas Chromatography

The use of bioinsecticides such as essential oils has been effectively evaluated in recent years for pest insect control. However, few studies have determined the persistence of these compounds in stored grains. The aim of this study was to optimize and validate a fast, effective, and safe method for extracting residues of linalool and estragole (main components of basil essential oil) from maize grains and to evaluate the persistence of these compounds in the grains. The headspace solid-phase microextraction coupled with gas chromatography with a flame-ionization detector (HS-SPME-GC/FID) was optimized by employing a central composite factorial design, in which the best conditions for the extraction were achieved by using a 4-min fiber exposure and an extraction temperature of 30 degrees C. The performance of the method was assessed by studying the selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy. The LOD and LOQ values were 0.045 and 0.15 mu g kg(-1), for linalool, and 0.054 and 0.18 mu g kg(-1), for estragole, respectively. The determination coefficients (R-2) of the calibration curves were greater than 0.99. The relative recovery of the compounds ranged from 76.0 to 103.7%, with a coefficient of variation under 14%. The proposed analytical method was successfully applied to assess the persistence of linalool and estragole in treated maize grains. After 48 h, no residue was detected in the samples, demonstrating that these compounds have low persistence and can be safely used as bioinsecticides in maize grains.

Automated summary

The study optimized a fast and effective method for extracting linalool and estragole residues from maize grains, and evaluated their persistence in the grains. The proposed method showed good selectivity, linearity, and precision, with low detection limits for both compounds. The results indicated that linalool and estragole have low persistence in treated maize grains, making them safe for use as bioinsecticides.