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 microg 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.

No abstract

Sudan dyes have been found to be added to chilli and chilli products for illegal colour enhancement purposes. Due to the possible carcinogenic effect, they are not authorized to be used in food in the European Union or the USA. However, over the last few years, many products imported from Asian and African countries have been reported via the Rapid Alert System for Food and Feed in the European Union to be contaminated with these dyes. In order to provide fast screening method for the detection of Sudan I (SI), which is the most widely abused member of Sudan dyes family, a unique (20 min without sample preparation) direct disequilibrium enzyme-linked immunosorbent assay (ELISA) was developed. The assay was based on polyclonal antibodies highly specific to SI. A novel, simple gel permeation chromatography clean-up method was developed to purify extracts from matrices containing high amounts of fat and natural pigments, without the need for a large dilution of the sample. The assay was validated according to the Commission Decision 2002/657/EC criteria. The detection capability was determined to be 15 ng g(-1) in sauces and 50 ng g(-1) in spices. The recoveries found ranged from 81% to 116% and inter- and intra-assay coefficients of variation from 6% to 20%. The assay was used to screen a range of products (85 samples) collected from different retail sources within and outside the European Union. Three samples were found to contain high amounts (1,649, 722 and 1,461 ng g(-1)) of SI by ELISA. These results were confirmed by liquid chromatography-tandem mass spectrometry method. The innovative procedure allows for the fast, sensitive and high throughput screening of different foodstuffs for the presence of the illegal colorant SI.

A multi-residue method for the simultaneous determination of 84 veterinary drug residues (benzimidazoles, quinolones, nitromidazoles, β-lactams, macrolides, triphenylmethane dyes, sulphonamides and tetracyclines) in chicken muscle tissue has been developed. Sample preparation is a simple one-step procedure based on liquid extraction with ethylenediamine tetraacetic acid-succinate buffer and acetonitrile, followed by phase separation and evaporation of the supernatant. The extract was diluted with 0.1% formic acid and analysed by using LC-MS/MS. The method has been validated in chicken muscle below the individual MRLs for each analyte. Recoveries of analysed drugs at fortified levels (2.5-80 ng g(-1)) were between 60% and 100% for most compounds, corrected for signal suppression and enhancement. Acceptable results regarding linearity of the method, precisions and LOQs were achieved for 84 of 91 investigated substances. The trueness was in the range of ±10%. The LOD ranged from 0.7 to 20 ng g(-1), and the LOQ ranged from 2.0 to 48 ng g(-1) (signal/noise 10-30) for all analytes and was below the established MRL of each compound.

No abstract