Development of an indirect ELISA for the determination of ethyl carbamate in Chinese rice wine

- Haptens against ethyl carbamte were firstly synthesized, and used to test their efficacy in eliciting antibody.
- A high specific polyclonal antibody with affinity to xanthyl ethyl carbamte (XEC) was produced.
- A facile and rapid EC chemical derivatization approach suitable for determination of EC by ELISA was designed.
- An indirect ELISA showing potential for monitoring ethyl carbamate in vast numbers of samples was constructed.

The widespread occurrence of ethyl carbamate (EC, 89.09 Da), a group 2A carcinogen, in fermented foods and alcoholic beverages has raised worldwide public health concern. Immunoassay for EC is unavailable due to the simple and small structure of EC. In this work, an initial attempt to produce antibody specific for EC, by using 4-((ethoxycarbonyl)amino)butanoic acid as hapten, was made but failed. However, since EC can easily react with 9-xanthydrol to form xanthyl ethyl carbamate (XEC), two haptens based on XEC structure were designed and synthesized. Polyclonal antibody against XEC, instead of EC was obtained and then used to develop a competitive indirect ELISA for EC via a pre-analysis derivatization. After optimization, the ciELISA was applied in analyzing Chinese rice wine with detection limit of 166 μg/L, and negligible cross-reactivity with EC analogs. Recoveries of EC in fortified samples were from 84.4% to 100.9%, with coefficients of variation below 10%. Results for analysis of real samples by the ci-ELISA correlated well with that by reference method GC-MS, suggesting the good accuracy and reproducibility of the proposed method. This is the first report of an immunoassay capable of detecting EC, which is suitable for monitoring EC in a large amount of samples.

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