Microwave-assisted rapid preparation of monodisperse superhydrophilic resin microspheres as adsorbent for triazines in fruit juices

Monodisperse superhydrophilic melamine formaldehyde resorcinol resin (MFR) microspheres were prepared in 90 min at 85 °C via a microwave-assisted method with a yield of 60.6%. The obtained MFR microspheres exhibited narrow size distribution with the average particle size of about 2.5 µm. The MFR microspheres were used as absorbents to detect triazines in juices followed by high performance liquid chromatography tandem mass spectrometry. Various factors affecting the extraction efficiency were investigated. Under the optimized conditions, the built method exhibited excellent linearity in the range of 1–250 μg L⁻¹ (R² ≥ 0.9994) and lower detection limits (0.3–0.65 μg L⁻¹). The relative standard deviations of intra- and inter-day analyses ranged from 3% to 7% and from 2% to 7%, respectively. The method was applied to determine six triazines in three juice samples. At the spiked level of 3 μg L⁻¹, the recoveries were in the range of 90–99% with the relative standard deviations ≤ 8%.