Solid-phase extraction (SPE) was carefully optimised for preconcentration of 2-4-dimethylaniline (2,4-DMA) and 2,4-dimethylformanilide (DMF) from honey samples. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used for the separation and quantification of these analytes. By applying the SPE procedure with 200 mg of OASIS HLB sorbent, the limits of detection achieved in honey samples can be lowered to 0.41 µg·kg-1 for 2,4-DMA and 0.69 µg L-1 for DMF. The proposed method achieves good recoveries (81.1-114%) and precision (RSD 1.07-4.05%, n = 3) for analysed honey sample spiked at two concentration levels 1 µg L-1 and 2 µg L-1. The results demonstrated our method can be applied as a simple way for sample preparation of honey samples for determination of amitraz degradation products. In 1 out of 5 of the analysed Polish honey samples, the DMF residues exceed the maximum residual limits (0.2 mg·kg-1 for total amitraz residues).
Keywords: 2,4-DMA; DMF; Honey; amitraz degradation products; liquid chromatography mass spectrometry (LC-MS/MS); solid-phase extraction (SPE).