Improvement of chemical analysis of antibiotics. XI. Simultaneous fluorodensitometric determination of polyether antibiotics.
A simultaneous determination of three polyether antibiotics, salinomycin, monensin and lasalocid, was established by silica gel and RP-18 high-performance thin-layer chromatography (HPTLC) using 18,19-dihydrosalinomycin and 18,19-dihydro-20-ketosalinomycin as internal standards. Fluorescent derivatives of the polyethers were prepared by reaction of their sodium salts with 1-bromoacetylpyrene and Kryptofix 222 in acetonitrile. A silica gel HPTLC plate with carbon tetrachloride-ethyl acetate-acetonitrile (50:5:10) as a solvent system and a RP-18 HPTLC plate with dichloromethane-ethyl acetate-acetone-acetonitrile (15:2:1:55) gave satisfactory separations of the five pyrenacyl esters of salinomycin, monensin, lasalocid, 18,19-dihydrosalinomycin and 18,19-dihydro-20-ketosalinomycin. Under these conditions the internal standard 18,19-dihydrosalinomycin was found to be suitable for the simultaneous determination of salinomycin and monensin, and 18,19-dihydro-20-ketosalinomycin for lasalocid. A linear relationship was obtained between the fluorescence intensity and the amount of each antibiotic in the range 2-14 ng. The detection limit of the three antibiotics was 100 pg.
D002855:Chromatography, Thin Layer; D003720:Densitometry; D007832:Lasalocid / Q000032:analysis*; D008985:Monensin / Q000032:analysis*; D011714:Pyrans / Q000032:analysis; D012997:Solvents; D013050:Spectrometry, Fluorescence; D000095662:Polyether Polyketides
D007832:Lasalocid; D008985:Monensin; D011714:Pyrans; D012997:Solvents; C010327:salinomycin; D000095662:Polyether Polyketides