A method was developed and validated for determination of tryptoquialanines A and C in orange samples on epicarp (exterior peel), mesocarp (white peel), and endocarp (fruit juice) based on QuEChERS extraction and LC-MS/MS analysis. The method showed an excellent linearity over a range of 5-400 μg kg-1, with r2 ≥ 0.998. The limits of detection (LOD) and quantification (LOQ) were 5 and 10 µg kg-1, respectively. Recoveries showed values between 57 and 101%, with RSD ≤ 12%. Analysis of infected oranges showed diffusion of the alkaloids between the orange layers after 4 days post infection in concentrations > LOQ. Mycotoxin diffusion to healthy oranges after direct contact with infected oranges for 48 h, showed alkaloid concentrations ≥10 µg kg-1 on epicarp layer. The developed method can be easily applied for quality control in routine analysis of orange fruit due to the high risk that these tremorgenic alkaloids represent to human health.
Keywords: Mycotoxins; Penicillium digitatum; QuEChERS; Tryptoquialanines.
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