# QuEChERS Combined with Low-Temperature Partitioning and GC–MS as an Analytical Strategy for the Determination of Multiclass Pesticide Residues in Cocoa Beans

## TL;DR

A new method combining QuEChERS and low-temperature partitioning with GC–MS is developed to detect pesticide residues in cocoa beans.

## Contribution

A simplified cleanup strategy using low-temperature partitioning is introduced for multiclass pesticide analysis in complex matrices.

## Key findings

- The method detected permethrin in five out of 15 cocoa samples from Brazil.
- Limits of detection ranged from 4.16 to 6.95 μg kg–1 with recoveries between 70–120%.
- Low-temperature partitioning proved effective for cleaning complex cocoa matrices.

## Abstract

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 (24–1) 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.