Polyether Antibiotics in Animal Feed

Our updated Method Abstract 264 describes the analysis of Monensin, Salinomycin, Narasin, & Lasalocid in Animal Feeds.

Polyether Antibiotics are commonly used for preventing coccidiosis and other infections in poultry and for improving feed efficiency for beef cattle and swine. The use of Polyether Antibiotics is strictly regulated, with only specific ionophores approved for use in feeds intended for different animals.

Analysis of Polyether Antibiotics by HPLC with post-column derivatization and UV/Vis detection has been proven to successfully identify and quantify Monensin, Narasin and Salinomycin in medicated feeds, supplements and premixes as well as to determine trace contamination levels in non-medicated feeds [1, 2].

Post-column derivatization of Polyether Antibiotics is done using highly acidic Vanillin or DMAB reagents. The Pinnacle PCX derivatization system (Pickering Laboratories, Inc.) has an inert flow path and automated system wash capabilities that make it uniquely suitable for handling corrosive reagents. The two-pump system is recommended to extend reagent stability, but the single-pump system for this application is also available.

Adding a Fluorescence detector to the instrumentation allows for using the same extraction procedure and HPLC conditions to also determine Lasalocid, which doesn’t require post-column derivatization.

Chromatograms of Polyether AntibioticsMETHOD
Sample Preparation
To 25 g of finely ground feed sample, add 100 mL of extraction solution (90% Methanol – 10% water). Shake for 1 hour at high speed using a mechanical shaker. Let the solids settle and filter an aliquot of the extract for injection. Dilute with extraction solution if needed to fit the calibration curve. Use a 2.5 g portion when testing premixes.

Analytical conditions
Analytical Column: Polyether Column, C18, 4.6 x 250 mm, Catalog No 2381750
Temperature: 40 ºC
Flow Rate: 0.7 mL/min
Mobile Phase: 90% Methanol, 10% of 5% Acetic Acid solution in water, isocratic
Injection volume: 20 μL

Post-Column Conditions
Post-column System: Pinnacle PCX
Reactor Volume: 1.4 mL
Reactor Temperature: 90 °C
Reagent 1: Concentrated Sulfuric acid / Methanol (4:96 v/v)
Reagent 2: 60 g of Vanillin in 950 mL of Methanol
Reagent Flow Rate: 0.3 mL/min
Detection: UV/VIS 570 nm (for Lasalocid – FLD, Ex. 322 nm, Em. 370 nm)

Analysis of Polyether Antibiotics by HPLC with Post-column derivatization is a robust and sensitive method that utilizes standard equipment and could easily be adopted by testing laboratories. It allows for testing of different ionophores at wide range of concentrations,
including at trace levels. Using Pinnacle PCX post-column derivatization system, factory configured for the analysis, guarantees stable and reproducible results.

The full application note as well as our complete Product Catalog can be downloaded from our website: www.pickeringlabs.com

table for polyether antibiotics