Method Validation and Evaluation of Safrole Persistence in Cowpea Beans Using Headspace Solid-Phase Microextraction and Gas Chromatography

Abstract

Bioinsecticides are regarded as important alternatives for controlling agricultural pests. However, few studies have determined the persistence of these compounds in stored grains. This study aimed at optimizing and validating a fast and effective method for extraction and quantification of residues of safrole (the main component of Piper hispidinervum essential oil) in cowpea beans. It also sought to assess the persistence of this substance in the grains treated by contact and fumigation. The proposed method used headspace solid-phase microextraction (HS-SPME) and gas chromatography with a flame ionization detector (GC/FID). Factors such as temperature, extraction time and type of fiber were assessed to maximize the performance of the extraction technique. The performance of the method was appraised via the parameters selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy. The LOD and LOQ of safrole were 0.0057 and 0.019 μg kg−1, respectively and the determination coefficient (R2) was >0.99. The relative recovery ranged from 99.26 to 104.85, with a coefficient of variation <15%. The validated method was applied to assess the persistence of safrole residue in grains, where concentrations ranged from 1.095 to 0.052 µg kg−1 (contact) and from 2.16 to 0.12 µg kg −1 (fumigation). The levels measured up from the fifth day represented less than 1% of the initial concentration, proving that safrole have low persistence in cowpea beans, thus being safe for bioinsecticide use. Thus, this work is relevant not only for the extraction method developed, but also for the possible use of a natural insecticide in pest management in stored grains.

Latest Improvements and Expanding Applications of Solid-Phase Microextraction

“…The volatile pesticides can be extracted by HS-SPME, while DI extraction is appropriate for the nonvolatile pesticides. The method integrating HS-SPME with GC-FID has been employed to determine the safrole concentrations in cowpea beans, confirming the low persistence of safrole . The flexible MOF-508 has been prepared as a novel SPME coating for DI extraction of diazinon and chlorpyrifos in wheat samples, and a practical method has been developed with low LODs, wide linear range, and excellent repeatability …”

“…The method integrating HS-SPME with GC-FID has been employed to determine the safrole concentrations in cowpea beans, confirming the low persistence of safrole. 161 The flexible MOF-508 has been prepared as a novel SPME coating for DI extraction of diazinon and chlorpyrifos in wheat samples, and a practical method has been developed with low LODs, wide linear range, and excellent repeatability. 162 Meat, brain tissue, and plasma samples have been collected from a variety of animals for in vitro analysis.…”