Use of polypyrrole ferrite microparticles and liquid chromatography-mass spectrometry for testing natural grass...

An analytical methodology based on the combination of dispersive magnetic solid-phase extraction (DMSPE) and liquid chromatography-mass spectrometry (LC-MS) is proposed to explore the occurrence of 13 mycotoxins (aflatoxins B₁, G₁, B₂, and G₂; deoxynivalenol; T-2 toxin; ochratoxin A; HT-2 toxin; enniatins A, A₁, B, and B₂; and beauvericin) and their derivatives in natural grass samples. Magnetic microparticles (Fe₃O₄) coated with polypyrrole (PPy) polymer were used in DMSPE sample treatment as adsorbent phase, and Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy have been used for its characterization. The experimental parameters influencing the adsorption and desorption steps of DMSPE have been optimized. Method validation has been carried out obtaining limits of quantification between 0.07 and 92 μg kg^-1 corresponding to enniatin B or A₁ and DON, respectively. A total of 83 natural grass samples from 8 dehesa farms were analysed. Enniatin B was found in all the samples (0.29 to 488 μg kg^-1 concentration range) followed by enniatin B₁ (92.8% of the samples) with a 0.12-137 μg kg^-1 concentration range. Moreover, co-occurrence of mycotoxins was studied and between 2 and 5 mycotoxins appeared simultaneously in 97.6% of the samples. Distribution of the contamination according to natural grass location was also investigated.