Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 6, 1998
Publication Date: N/A
Interpretive Summary: Halofuginone (Hal) is a feed additive used to control parasites (coccidia) on the skin of broiler chickens. The drug is placed in the feed and the animals. The chickens must be taken off the Hal-treated feed at least 4 days before they can be used for food. Currently, broiler chickens are being tested to be sure that they have been removed from the Hal-treated feed for the appropriate amount of time before use. The current method for determining the level of Hal in chicken liver tissue utilizes a time- consuming and complicated extraction procedure followed by high- performance liquid chromatography analysis. That procedure will not allow high sample throughput. We evaluated a method based on a fast, simple extraction of chicken liver tissue followed by analysis of Hal by an antibody-based immunoassay. Antibodies are substances which are produced by the immune system in response to foreign substances which enter the body. Once the antibodies are isolated, they can be used to detect the foreign substances against which they were generated. The results of the two methods compare favorably. In most cases, the recovery was higher using the immunoassay method. In addition, the immunoassay method does not require the use of chemicals that could be harmful to the environment and require proper disposal. The results clearly demonstrate that the immunoassay method could be used as a screening method (a way to look for Hal in large numbers of samples) for the analysis of Hal in chicken liver tissue.
Technical Abstract: The quinazolinone, halofuginone (Hal), is a feed additive used world wide to prevent coccidiosis in commercial poultry production. The current regulatory method for determining the action level of Hal residues in poultry involves the measurement of parent Hal in liver tissue by HPLC. That procedure is not amenable to high sample throughput due to a complex and tedious sample preparation scheme. A competitive enzyme-linked immunosorbent assay (cELISA) that can be used as a screening tool for determining Hal in chicken liver tissue is described. The cELISA method was evaluated using standard curves made in both Assay Buffer and chicken liver extract, and it was demonstrated that standard curves made in Assay Buffer could be utilized. HPLC vs. cELISA results were obtained during two studies; the first study utilized spiked chicken liver tissue, and the second study used both spiked chicken liver tissue as well as incurred levels of Hal in chicken liver tissue. There was good agreement in the results obtained by HPLC and cELISA. However, in most cases the recovery was higher using the cELISA method vs. the HPLC method. In addition, the cELISA method does not require the use of organic solvents. These data clearly demonstrate that the cELISA method could be used as a screening method for Hal in samples of chicken liver tissue.