Comparison of XAD-2 column and blue cotton batch techniques for isolation of metabolites of 2-amino-3-methylimidazo[4,5-f]quinoline.

In studies on the metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in the rat, two methods were used to concentrate IQ and its metabolites in urine: XAD-2 columns and blue-cotton extraction. These methods were compared as to the total recovery of 14C-label and the results of high-performance liquid chromatography (HPLC) of the main metabolites. In the HPLC analysis, three major peaks in the polar region and two adjacent peaks in the nonpolar region having radioactivity were found in the urine from rats given 14C-IQ. XAD-2 columns adsorbed approximately 65% and blue cotton 23% of the applied isotope from the urinary metabolites. Both methods efficiently adsorbed and totally released the relatively nonpolar compounds in a mixture of metabolites, including the compound administered, IQ. However, they failed to retain the more polar metabolites. Thus, both the XAD-2 column and blue cotton adsorption techniques may be useful mainly to concentrate nonpolar compounds from larger volumes of aqueous solutions.