Formation of semicarbazide (SEM) in food by hypochlorite treatment: is SEM a specific marker for nitrofurazone abuse?

Abstract

Semicarbazide (SEM) is considered to be a characteristic protein-bound side-chain metabolite of the banned veterinary drug nitrofurazone. It is therefore used as a marker for nitrofurazone abuse. Recently, there has been concern about other sources of SEM in tissue samples, which are not linked to the illegal use of nitrofurazone. The present studies have shown that SEM can occur naturally, e.g. in algae, shrimps and eggs, and is formed from natural substances, e.g. arginine and creatine. A significant formation of SEM was observed in samples treated with hypochlorite commonly used in food processing for disinfection or bleaching. SEM was formed in different kinds of nitrogen compound-containing samples (0.3–20 μg kg⁻¹) after treatment with 1% active chlorine. It was detected in the mg kg⁻¹ range after hypochlorite treatment (0.015% active chlorine) of creatine. Lower levels were also formed from creatinine, arginine and urea. SEM present in hypochlorite-treated carrageenan proved mostly to occur in the tissue-bound form. Therefore, differentiation between SEM from nitrofurazone abuse and SEM originating from natural constituents (due to hypochlorite treatment) seems not to be unambiguously possible.

Keywords:

• free and tissue bound semicarbazide
• hypochlorite
• nitrofuran metabolite
• nitrofurazone
• nitrogen compounds
• disinfections
• bleaching
• carrageenan

Acknowledgements

The authors thank Alexander Fekete, Tatjana Groß, Marco Gangnus, Peter Hach and Silke Maß for nitrofuran analysis and evaluation, Stefan Weigel as well as Wittko Francke and Heinrich Hühnerfuß, University of Hamburg, Institute for Organic Chemistry, for suggestions and discussion, and Bert Pöpping for proofreading and editing the manuscript.