Factorial Optimization and Validation of Solid–Liquid Extraction with Low-Temperature Partitioning of Pesticide Residues from Pequi Pulp Using High-Performance Liquid Chromatography with a Photodiode Array Detector (HPLC-DAD)

In this study, we developed a solid-liquid extraction method with low-temperature partitioning for extracting six pesticide residues (carbendazim, diuron, carboxin, chlorpyrifos, terbutylazine, and thiabendazole) from pequi pulp. Pequi is a key fruit of the Brazilian Cerrado biome, which is characterized by its intensive agricultural activity. This sample preparation technique was chosen for its simplicity, minimal analyst intervention, and effective extraction of pesticide residues from food samples. The selected pesticides reflect those widely used in grain and sugar cane monocultures within the Cerrado biome. The optimization of pesticide extraction from pequi pulp samples was conducted by using experimental design approaches. Pesticide recoveries ranged from 86 to 118% under optimized conditions, which included 500 mg of sample, 7.2 mL of ethyl acetate, 3.4 mL of water, and a freezing time of 3 h. The validated method, performed in a single step without additional cleanup procedures, demonstrated selectivity, robustness, and limits of quantification below 6.9 μg kg^-1, as well as high efficiency. No pesticide residues were detected in the pequi samples collected from strategic cities in the Cerrado. This absence may be attributed to the protective nature of the thick external epicarp, which shields the pulp from pesticide contamination, even in areas with intensive agricultural activity.