IMPROVEMENT OF CHEMICAL-ANALYSIS OF ANTIBIOTICS .20. BASIC STUDY ON HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF 4 POLYETHER ANTIBIOTICS PRE-DERIVATIZED WITH 1-BROMOACETYLPYRENE

A high-performance liquid chromatographic method for the determination of the polyether antibiotics (PEs), salinomycin (SL), monensin (MN), lasalocid (LA) and narasin (NA), based on a precolumn reaction system using 1-bromoacetylpyrene (1-BAP) as a fluorescence reagent, was established. Six standards of 1-pyrenacyl eaters (PEs-PYs) including two of l-pyrenacyl esters of internal standards, 18,19-dihydrosalinomycin (DSL) and 18,19-dihydro-20-ketosalinomycin (DKSL), were separated within 30 min on a Develosil 5C(18) (5 mu m) column (250 x 4.6 mm I.D.) with methanol-water (97:3) as the mobile phase at a flow-rate of 1.0 ml/min and were detected at lambda(ex) 360 nm, lambda(em) 420 nm. This system was also effective for the separation between unused 1-BAP and PEs-PYs and the simultaneous determination of SL, MN, LA and NA was achieved at concentrations from 0.2 to 100 mu g/ml. At concentrations of less than 10 mu g/ml a silica gel cartridge was effective in eliminating the excess of unused reagents. Four calibration graphs with the internal standard method were linear between 20 and 100 mu g/ml, 2 and 10 mu g/ml and 0.2 and 1.0 mu g/ml. The method is applicable to feed and residue analyses.