QuEChERS Combined with Low-Temperature Partitioning and GC-MS as an Analytical Strategy for the Determination of...

The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) technique has gained wide acceptance worldwide due to its efficiency in multiresidue pesticide analysis across diverse matrices. Continuous improvements have further enhanced its applicability and accuracy. In this study, QuEChERS was combined with low-temperature partitioning (LTP) for the simultaneous determination of 15 multiclass pesticide residues in cocoa beans by gas chromatography-mass spectrometry (GC-MS). A fractional factorial design (2^4-1) was employed to optimize extraction parameters. The optimal conditions comprised 2.0 g of sample, 8.0 mL of acetonitrile and 2.0 mL of water as the extraction solvent, 150 mg of PSA sorbent, vortex extraction for 3 min at 2500 rpm, and partitioning for 24 h in a conventional freezer. The method was validated, with limits of detection and quantification ranging from 4.16 to 6.95 μg kg^-1 and 13.9 to 23.1 μg kg^-1, respectively. Recoveries were within 70-120%. The procedure was applied to 15 cocoa samples from Bahia and Pará, Brazil, and permethrin was the only pesticide detected, occurring in five samples. These results demonstrate that the proposed approach is effective and reliable, highlighting low-temperature partitioning as a simplified cleanup strategy for complex matrices such as cocoa.