A Technique for Assay of Goitrogens in Feed

Abstract

An assay procedure has been described which can be used to detect minute amounts (0.5–2 ppm.) of residues in tissues of goitrogen-fed animals. The technique described in rats consists in determining 24-hour I₁₃₁ uptake after feeding the goitrogen (or tissues) for a period of 4 days and then comparing it with control I₁₃₁ uptakes. A low-iodine diet, by enhancing I₁₃₁ uptake, increased the sensitivity of the assay technique. By this method, tapazole at 0.00005−0.0002% (½–2 ppm.) and carbimazole at 0.0001−0.001% (1–10 ppm.) in low iodine feed could be detected as shown by reduced I₁₃₁ uptake in comparison with controls. Copyright © . .