The content of zearalenone and its metabolites in urine and tissue samples from pigs fed zearalenone-contaminated oats was established by analytical methods combining solid-phase extraction cleanup of the samples with highly selective liquid chromatography-mass spectrometry (LC-MS)/MS detection. Investigation of the urine samples revealed that approximately 60% of zearalenone was transformed in vivo to alpha-zearalenol and its epimer beta-zearalenol in a mean ratio of 3:1. Zeranol and taleranol as further metabolites could only be detected in trace amounts. Zearalanone was identified at considerable concentrations, though only in a couple of samples. In contrast, liver samples contained predominantly alpha-zearalenol, and to a minor extent beta-zearalenol and zearalenone, with a mean ratio of alpha-/beta-zearalenol of 2.5:1, while zeranol, taleranol, or zearalanone could not be identified in any of the investigated samples. The degree of glucoronidation was established for zearalenone as 27% in urine and 62% in liver; for alpha-zearalenol as 88% in urine and 77% in liver; and for beta-zearalenol as 94% in urine and 29% in liver. Analyses of muscle tissue revealed relatively high amounts of nonglucuronidated zeranol and alpha-zearalenol together with traces of taleranol and zearalenone, indicating that the metabolism of zearalenone and its metabolites is not restricted to hepatic and gastrointestinal metabolic pathways.
Key WordsColumn liquid chromatography Tandem mass spectrometry Zeranol, zearalenone and zearalenol
SummaryAn LC-MS/MS method has been developed for the sensitive determination of the anabolic compound zeranol, its epimer taleranol and the mycotoxins zearalenone, azearalenol and fl-zearalenol in animal urine and meat samples. Sample preparation included extraction of meat samples and enzymatic digest of urine samples followed by solid phase extraction with RP-18 columns for sample clean-up. Mass spectrometric determination was carried out with an atmospheric pressure chemical ionisation interface (APCI) in the multi-reaction monitoring mode (MRM). Using the negative ion mode, a limit of detection between 0.1 and 0.5 ppb and a limit of determination between 0.5 and 1 ppb could be achieved. With zearalanone (ZAN) as internal standard, a linear range between 0.5 (1.0) and 100ppb in urine samples (cow, pig) and between 1 and 100 ppb in meat samples (cow, calf, pig) could be established. Depending on the biological matrix and analyte, standard deviations were below 8.5 %, with average recovery rates around 86 % to 102 % in spiked samples. The usefulness of the method developed was demonstrated via several contaminated cow and pig urine samples. the mycotoxins zearalenone (ZON) and e-zearalenol (7-ZOL) that can be carried over from contaminated feedstuffto animals [2][3][4]. ZON, e-ZOL and its epimer/%zearalenol (fl-ZOL) are produced by several Fusarium species that colonize grains [5]. High amounts can be found on maize, wheat, barley and oats. All three compounds exhibit distinct HC
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