4.3.5. Calculations

Mycotoxin quantification was performed by the isotopic dilution approach using 13C-fully labeled mycotoxins as internal standard. For each injection, the ratio of the peak area of each analyte to the peak area of the respective labelled analogue was calculated. The peak area of 15-AcDON was divided by the peak area of 13C17-3-AcDON. These peak area ratios are used in all subsequent calculations. A calibration curve for each of the seven analytes (NIV, DON, 3-AcDON, 15-AcDON, HT-2, T-2, and ZEN) was prepared by plotting the peak area ratios of each analyte calculated in the calibration solutions in Table 2 (*Y*-axis, dependent variable) against the corresponding amount (μg) of analyte injected on column (*X*-axis, independent variable). The mass fraction of each mycotoxin, w, in microgram per kilogram of the sample was calculated according to Formula (1):

$$w\_{\parallel} = \left(\frac{R}{a} - \frac{b}{a}\right) \times \frac{V\_1}{V\_2} \times \frac{1000}{m\_{SPE}}\tag{1}$$

where:


The sample equivalent weight (*mSPE*) was calculated according to Formula (2):

$$m\_{SPE} = \frac{m \times V\_4}{V\_3} \tag{2}$$

where:


**Author Contributions:** Methodology V.M.T.L. and A.D.G.; formal analysis, B.C.; data curation, B.C., A.D.G., V.M.T.L.; writing—original draft preparation and review, V.M.T.L., A.D.G., M.P.; supervision, M.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research leading to these results has received funding by the European Commission under the "Agreement for the provision of technical services to NEN", Ref.SA/CEN/ENTR/520/2013-17. Contract item: 2013-17.4.

**Acknowledgments:** We express our appreciation to the following collaborators for their participation in the collaborative study: Pedro A. Burdaspal, National Center for Food (Spain); Ivano Volpicella, University of Bari Aldo Moro (Italy); Sylvain Chéreau, National Institute for Agricultural Research (France); Francesca Ferrieri, Regional Agency for Environmental Protection-ARPA (Apulia, Italy); Marta Ferro, Regional Agency for Environmental Protection-ARPAL (Liguria, Italy); Carlos Goncalves and Joerg Stroka, EC-Joint Research Centre -IRMM (Belgium); Bart Huybrechts, Veterinary and Agrochemical Research Centre CODA-CERVA (Belgium); John Keegan, Public Analyst's Laboratory (Ireland); Martina Ivesic, Institute of Public Health-Andrija Stampar Teaching Institute of Public Health (Croatia); Susan MacDonald, Food and Environment Research Agency (United Kingdom); Hans Mol, RIKILT Wageningen University and Research (The Netherlands); Ivan Pecorelli, Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche (Italy); Michael Sulyok, University of Natural Resources

and Applied Life Sciences-IFA Tulln (Austria); Michele Suman, Barilla G. and R. F.lli SpA (Italy); Mark W. Sumarah and Justin B. Renaud, Agriculture and Agri-Food Canada (Canada).

**Conflicts of Interest:** The authors declare no conflict of interest.
