Qualitative screening of undesirable compounds from feeds

25 26 This article describes the development, validation and application of a rapid screening method 27 for the detection and identification of undesirable organic compounds in aquaculture products. 28 A generic sample treatment was applied without any purification or preconcentration step. After 29 extracting the samples with acetonitrile/water 80:20 (0.1% formic acid), the extracts were 30 centrifuged and directly injected in the LC-HRMS system, consisting of ultra-high performance 31 liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry 32 (UHPLC-QTOF MS). A qualitative validation was carried out for over 70 representative 33 compounds, including antibiotics, pesticides and mycotoxins, in fish feed and fish fillets spiked 34 at 20 μg/Kg and 100 μg/Kg. At the highest level, the great majority of compounds were 35 detected (using the most abundant ion, typically the protonated molecule) and unequivocally 36 identified (based on the presence of two accurate-mass measured ions). At the 20 μg/Kg level, 37 many contaminants could already be detected although identification using two ions was not 38 fully reached for some of them, mainly in fish feed due to the complexity of this matrix. 39 Subsequent application of this screening methodology to aquaculture samples made it possible 40 to find several compounds from the target list, such as the antibiotic ciprofloxacin, the 41 insecticide pirimiphos-methyl and the mycotoxins fumonisin B2 and zearalenone. A 42 retrospective analysis of accurate-mass full-spectrum acquisition data provided by QTOF MS 43 was also made, without neither reprocessing nor injecting the samples. This allowed the 44 detection and tentative identification of other organic undesirables different than those included 45 in the validated list. 46 47 48 49