RETENTION MECHANISMS APPLIED IN SOLID PHASE EXTRACTION FOR SOME POLAR COMPOUNDS

Two basic mechanisms were applied for studying some polar compounds of pharmaceutical interest (captopril, atenolol, and metformin) by solid phase extraction, using an octadecilsilica based adsorbent. The retention of these compounds was achieved under reversed-phase or ion-pair mechanisms using cartridges containing two different sorbent loadings. The breakthrough parameters (hold-up, breakthrough, and retention volumes) were measured for chosen model solutes from the experimental data obtained by percolating the C18 cartridges with stock solutions for each compound. The experimental curves were fitted by means of Boltzmann’s function, and the regression parameters were used in calculating the breakthrough parameters.