Title: Comparison of ELISA and LC-MS/MS for the measurement of flunixin plasma concentrations in beef cattle after intravenous and subcutaneous administration
Authors: Shelver WL, Tell LA, Wagner S, Wetzlich SE, Baynes RE, Riviere JE, Smith DJ
Journal: J Agric Food Chem
Accepted date: 2013 Feb 21
Interpretive summary: Recently, regulators have measured illegal residue levels of the anti-inflammatory drug flunixin in cattle. The exact reason for these violations is not possible to determine, but the most likely causes would be too high of a dose, unapproved flunixin administration route, or too short of withdrawal time (the time from the last dose until the animal is marketed). This project investigated the effect that the dose route has on the time required for flunixin to deplete to levels acceptable for marketing; in addition, the usefulness of two very different analytical techniques for measuring flunixin was assessed. One method, known as ELISA, is very sensitive, easily performed, and is relatively inexpensive. The other method (HPLC-MS/MS) is precise and specific, but requires very expensive and sophisticated equipment; it is not typically cost effective for large numbers of samples. While both methods were useful for measuring relatively low flunixin concentrations, the ELISA assay tended to overestimate flunixin levels at times close to dosing. Nevertheless, it was convincingly shown that the ELISA assay would be a valuable, cost-effective tool for laboratories which do not have access to LC-MS/MS equipment.
Publication date: 2013 Mar 7
Related projects: Metabolic Fate of Chemical and Biological Contaminants