Defeathering with rosin results in rosin residue in duck skin, which may present as potential risk to human health. Dehydroabietic acid (DHAA) is a major component of rosin. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed for determination of DHAA in duck skin. A set of parameters was optimized, including coating antigen concentration, dilution of antiserum, dilution of HRP-IgG antibody, incubation time, and temperature for antigen reaction with antiserum. The indirect competitive ELISA yielded an excellent specificity against DHAA with low cross-reactivity toward other resin acids. The limit of detection and the working concentration range of DHAA in duck skin were 16.4 ng/g and from 40 to 8,060 ng/g, respectively. The indirect competitive ELISA was applied to the determination of DHAA in duck skin samples spiked with DHAA at different contents, and recoveries were found between 78.2 and 97.2%. Finally, DHAA contents in 32 duck samples were quantified by the indirect competitive ELISA and high performance liquid chromatography-fluorescence detector (HPLC-FLD) method. No significant difference was found between DHAA concentrations from indirect competitive ELISA and HPLC-FLD method for all samples, which indicated the indirect competitive ELISA established in this article was of the same accuracy as the HPLC-FLD method. The indirect competitive ELISA was simple, rapid, and reliable, which could be used to identify the duck carcasses defeathered with rosin in the market.
Keywords: ELISA; HPLC; dehydroabietic acid; duck; rosin.
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