Title: a)

Legend:
Chromatogram a) extract of kidney sample from a pig treated with fenbendazole, derivatized with pentafluorobenzyl bromide 1 + 2 - PFB derivatives of fenbendazole 3 + 4 - PFB derivatives of the metabolite fenbendazole sulphone Chromatogram b) extract of a blood sample from a pig treated with fenbendazole, derivatized with methyl iodide 1 + 2 - Me derivatives of fenbendazole 3 + 4 - Me derivatives of the metabolite fenbendazole sulphone 5 + 6 - Me derivatives of the metabolite oxfendazole