Development of an immunochromatographic assay for the ß-adrenergic agonist feed additive zilpaterol

Authors: Shelver, Weilin; Smith, David

Submitted to: Food Additives & Contaminants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2018
Publication Date: 6/6/2018
Citation: Shelver, W.L., Smith, D.J. 2018. Development of an immunochromatographic assay for the ß-adrenergic agonist feed additive zilpaterol. Food Additives & Contaminants: Part A. 35(8):1519-1529. https://doi.org/10.1080/19440049.2018.1463568.
DOI: https://doi.org/10.1080/19440049.2018.1463568

Interpretive Summary: Zilpaterol is a ß-adrenergic growth promoter that produces leaner meat, improves growth rates, and decreases feed consumption in cattle, goats, and sheep. Use of zilpaterol for cattle has been approved in the United States, Canada, Mexico and South Africa, but not in the European Union, China or most other countries. Because the legal use of zilpaterol in cattle has been approved in only a few countries, the detection of zilpaterol in live animals or in food animal urine and/or tissues is of interest to regulatory officials, importers, and exporters. Lateral flow assays (similar to a home pregnancy test kit) are portable, sensitive, and low cost, one-step tests that allow the quick detection of drug residues (within approximately 10 min). In this report, a user-friendly lateral flow assay was generated to detect zilpaterol in animal urine, tissues, and feed with no or simple sample preparation. This assay will allow the field-based rapid determination of animal exposure to zilpaterol in near real time and has applications for the detection of illegal zilpaterol use and for the detection of zilpaterol in edible meat products destined for import or export.

Technical Abstract: A zilpaterol immunochromatographic assay was developed as an economical and user friendly rapid detection method for zilpaterol. The assay sensitivity was 1.7 – 23.2 ng/g or mL with a variety of feed and animal matrices and did not cross react with clenbuterol or ractopamine. No sample pre-treatment of cattle and sheep urine was needed, but horse urine and feed required dilution, and muscle needed solvent extraction prior to testing. Of 32 incurred sheep urine samples tested, zilpaterol content was correctly identified in all but 2 samples. Horse urine containing >10 ng/mL of zilpaterol (n = 48) was correctly identified as zilpaterol positive. The assay correctly identified 0-day withdrawal sheep muscle samples as positive and the control and longer withdrawal day sheep as negatives. Zilpaterol stability in horse urine stored at -20 oC for 7 years was demonstrated.