Multiclass and multi-residue screening of mycotoxins, pharmacologically active substances, and pesticides in infant milk formulas through ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry analysis

Infant milk formulas are designed to substitute human milk when breastfeeding is unavailable. In addition to human milk and milk-derived products, these formulas can be a vehicle of contaminants. In this work, a multiclass method based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach was developed for the simultaneous determination of contaminants (n = 45), including mycotoxins and veterinary drug residues, occurring in infant milk formulas. By using an ultra-high-performance liquid chromatography quadrupole-Orbitrap coupled with high-resolution mass spectrometry analysis (UHPLC Q-Orbitrap HRMS; Thermo Fisher Scientific), further retrospective analysis of 337 contaminants, including pesticides, was achieved. The method was validated in accordance with European regulations and applied for the analysis of 54 infant milk samples. Risk assessment was also performed. Dexamethasone was detected in 16.6% of samples (range: 0.905–1.131 ng/mL), and procaine benzyl penicillin in 1 sample at a concentration of 0.295 ng/mL. Zearalenone was found in 55.5% of samples (range: 0.133–0.638 ng/mL) and α-zearalenol in 16.6% of samples (range: 1.534–10.408 ng/mL). Up to 49 pesticides, 11 veterinary drug residues, and 5 mycotoxins were tentatively identified via retrospective analysis based on the mass spectral library. These findings highlight the necessity of careful evaluation of contaminants in infant formulas, considering that they are intended for a vulnerable part of the population.