Method Abstract 104


Polyether antibiotics, such as Monensin, Narasin, and Salinomycin, in raw material, premix, liquid supplements, and final feeds, are best quantified using a HPLC equipped with a post-column reactor. The polyether antibiotics react, post-column, with Vanillin in the presence of sulfuric acid, and the resulting products can be detected at 520 nm. However, this corrosive reagent can adversely degrade most instruments. Pickering’s special post-column systems are comprised of non-metallic parts and washing pump head, which offers resistance to sulfuric acid. Special operating instructions will also be included with this instrument.


Analytical Conditionschart-m-104

Column: Polyether reversed-phase column, C18,
              4.6 x 250 mm, Catalog No. 2381750
Temperature: 40 °C
Flow Rate: 0.7 mL/min
Mobile Phase: Methanol/5 % acetic acid in water (90/10),  Isocratic

Post-column Conditions

Post-column System: Vector PCX or Pinnacle PCX (Non-metallic post-column derivatization system is required)
Reagent 1: Concentrated Sulfuric acid/Methanol (4:96 v/v)
Reactor 1: Ambient, 0.1 mL
Reagent 2: 60 g of Vanillin (or p-dimethylaminobenzaldehyde) in 950 mL of Methanol
Reactor 2: 90 °C, 1.4 mL
Flow Rate: 0.3 mL/min
Detection: UV-Vis detector: Vanillin λ=520 nm, DMAB λ=450 nm


1) M.R. LaPointe and H. Cohen, J.A.O.A.C., 71 (1988) 480–484.
2) J.M. Rodewald, J.N. Moran, A.L. Donoho, and M.R. Coleman, J.A.O.A.C., 75 (1992) 272–279.