CHICKEN ANTIBODY-BASED ELISA FOR THE DETECTION OF SPIRAMYCIN IN RAW-MILK

Spiramycin is used in veterinary medicine for the treatment of bacteri al and mycoplasmal infections. With regard-to toxicological safety a m aximum residue limit (MRL) of 200 mu g/kg for the sum of spiramycin an d neospiramycin (metabolite) in milk is fixed (EU-Regulation 1442/95). Up to now there is no screening test available for the simultaneous i dentification and quantification of spiramycin at the MRL. An enzyme i mmunoassay for the determination of spiramycin in raw milk is presente d. Hens were immunized using a spiramycin-BSA-conjugate produced in a two step coupling method. Specific antibodies (IgY) could be extracted from egg yolk by precipitation with polyethylene glycol. The ELISA wa s carried out as an indirect competitive antibody-capture test with a detection limit of 5.6 mu g/kg. Repeatability (r) of the ELISA was tes ted by analyzing standard solutions of spiramycin in raw milk (n = 6 f or each concentration). Coefficients of variation were between 5.1 and 7.9 %. Results after examination of spiked blind samples demonstrated that classification of positives and negatives as well as quantificat ion up to 150 mu g/kg is possible. For quantitative detection of spira mycin at the final MRL sample dilution may be necessary.