The determination of biurea: A novel method to discriminate between nitrofurazone and azodicarbonamide use in food products

• Published in: Analytica chimica acta 2007-03, Vol.586 (1-2), p.366-373
• Main Authors: Mulder, P.P.J., Beumer, B., Van Rhijn, J.A.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Animal Feed; Animals; Azo Compounds - analysis; Azodicarbonamide; Biurea; Bread; Breaded products; Carbon Isotopes - pharmacology; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, Liquid - methods; Exact sciences and technology; Flour; Food Analysis - methods; Mass Spectrometry - methods; Models, Chemical; Nitrofurazone; Nitrofurazone - analysis; Nitrogen Isotopes - pharmacology; Other chromatographic methods; Poultry; Semicarbazide; Semicarbazides - analysis; Spectrometric and optical methods; Urea - analysis
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2006.11.033

Recently doubts have arisen on the usefulness of semicarbazide as marker residue for the illegal use of the antibiotic nitrofurazone (NFZ) in aquaculture and poultry production. Most notably azodicarbonamide (ADC) has been implicated as an alternative source of semicarbazide. ADC is used in some countries as a dough conditioner at concentrations up to 45mgkg−1. The use of ADC-treated flour or dough in coated or breaded food products may generate false non-compliant results in the analytical method for nitrofurazone metabolites, which is currently in use. During the dough preparation process ADC is largely reduced to biurea, which can be considered as an appropriate marker residue of ADC. Thus far no methods have been published for the determination of biurea in food commodities. Due to its polar nature it is very difficult to generate sufficient retention on conventional C18 HPLC columns. With a TSK amide HILIC type column good retention was obtained. A straightforward extraction-dilution protocol was developed. Using a mixture of dimethyl formamide and water biurea was nearly quantitatively extracted from a variety of fresh, coated and processed products. Mass spectrometric detection was performed with positive electrospray ionisation. The sensitivity and selectivity of the mass spectrometer for biurea was very good, allowing detection at concentrations as low as 10μgkg−1. However, in some extracts severe ion suppression effects was observed. To overcome the implications of ion suppression on the quantitative performance of the method an isotopically-labelled biurea internal standard was synthesized and incorporated in the method. The method developed can be used effectively in nitrofurazone analysis to eliminate the risk of false non-compliant results due to the presence of azodicarbonamide-treated components in the food product.