Magnetic nanoparticles speed up mechanochemical solid phase extraction with enhanced enrichment capability for organochlorines in plants.

A mechanochemical magnetic solid phase extraction (MCMSPE) method was developed for a one-pot extraction and enrichment of organochlorine pesticides in tea leaves to demonstrate the advantage of using magnetic nanoparticles in the sample preparation process. The enriched analytes were subsequently detected by ultra-high performance liquid chromatography and gas chromatography mass spectrometry. The presence of magnetic metal-organic-framework (MMOF) (Fe3O4@MIL-100 (Fe)) nanoparticles help to rupture the cell walls in solid plant samples more thoroughly, and at the same time, act as a selective sorbent for the enrichment of target analytes. Compared to traditional methods, this approach significantly shortens the sample processing time from tens of minutes to tens of seconds. The parameters of the procedure were systematically studied and optimized to achieve good limits of detection (0.62-3.92 ng g-1, LOD S/N = 3), significantly improved recoveries (81.46-113.59%), and good reproducibility (RSD 2.63-9.87%, n = 5). The results indicated that this method can be applied for high throughput determination of organochlorine pesticides in tea leaves, and can be used for other dried plant samples.