Ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry detection of naturally occurring thiouracil in urine of untreated livestock, domesticated animals and humans

Julie Vanden Bussche (1) , Lynn Vanhaecke (1) , Yoann Deceuninck (2) , Klaas Wille (1) , Karen Bekaert (1) , Bruno Le Bizec (2) , Hubert de Brabander (3)

1 Veterinary Public Health and Zoonoses
2 LABERCA - Laboratoire d'étude des Résidus et Contaminants dans les Aliments
3 Veterinary Public Health and Food Safety

Thiouracil (TU) belonged to the xenobiotic thyreostats, which are growth-promoting agents, illegally used in animal production. Recently, it has been reported that thiouracil is suspected to have an natural origin. The EURL guidance paper (2007) acknowledged this, by stating that thiouracil concentrations below 10 µg L^-1 might have a natural origin derived from Brassicaceae consumption. The present research aimed at endorsing this possible natural occurrence. Urine samples of animals (livestock and domesticated) with known and unknown clinical backgrounds were analysed for thiouracil with a newly developed ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry analysis method without derivatisation. In addition, a small-scale 9-day human experiment with Brassicaceae vegetables was performed to investigate if this natural prevalence could be extrapolated to the human population. The untreated animals displayed thiouracil concentrations below 10 µg L^-1 acknowledging the alleged natural occurrence of thiouracil. As for the humans, in 66.7% of the urine samples thiouracil was found above the CC_α of 2.2 µg L^-1. However the correlation with the Brassicaceae diet proved not significant (p = 0.095). Nevertheless, these results clearly demonstrate the natural occurrence of thiouracil in urine of animals and humans. The exact origin of this natural thiouracil trace still needs to be identified.

Mots clés: Life Sciences

Julie Vanden Bussche, Lynn Vanhaecke, Yoann Deceuninck, Klaas Wille, Karen Bekaert, et al.. Ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry detection of naturally occurring thiouracil in urine of untreated livestock, domesticated animals and humans. Food Additives and Contaminants, 2011, 28 (02), pp.166. ⟨10.1080/19440049.2010.544681⟩. ⟨hal-00662387⟩