Organochlorine pesticide analysis in milk by gas-diffusion microextraction with gas chromatography-electron capture detection and confirmation by mass spectrometry.

Organochlorine pesticides (OCPs) are synthetic compounds less used nowadays due to their toxicity combined with slow degradation which leads to accumulation in the environment. Gas-diffusion microextraction (GDME) was employed prior to gas chromatography with electron capture detection (GC-ECD) and mass spectrometry (GC-MS). For the first time, the low-cost, eco-friendly GDME system was used to extract the OCPs directly from milk samples and associated with GC-ECD. Parameters that affect GDME's performance (extract volume, extraction time, and temperature) were optimized. The calibration curves of all OCPs (α- and β-hexachlorocyclohexane, lindane, hexachlorobenzene, p,p'-DDE, aldrin, dieldrin, and α-endosulfan) had coefficients of determination (r) ranging from 0.991 to 0.995, and limits of detection (LODs) values ranging from 3.7 to 4.8 µg L. This method also provided satisfactory values for precision with relative standard deviations (RSDs) lower than 10% and recoveries above 90%. As a proof-of-concept, several commercial milk samples were analyzed, aldrin was found in one of them but below the maximum residue limits.