RETENTION BEHAVIOR OF THE SULFOXIDE, SULFONE AND 2-AMINOSULPHONE METABOLITES OF ALBENDAZOLE IN ION-PAIR LIQUID-CHROMATOGRAPHY

The chromatographic behaviour of the sulphoxide, sulphone and 2-aminos ulphone metabolites of albendazole has been investigated as a function of the pH and the type and concentration of the pairing ions added to the mobile phase. Experiments were carried out using both tetrabutyla mmonium cations and octanesulphonate anions as pairing agents. The res ults showed that improvements of peak shape and marked differences in selectivity with alterations in elution order can be achieved by chang ing the ionisation state of the solutes and the type and the concentra tion of the pairing ion in the mobile phase. Although it was clear tha t at pH 2.3 the tetrabutylammonium cations exerted the conventional ef fect of a competing base whereas the octanesulphonate anions the conve ntional effect of a pairing agent, the lack of quantitative correlatio n and the exceptions at pH 7.4 indicated that the retention mechanisms may be more complex. (C) 1997 Elsevier Science B.V.