Tooptimizetheon-lineSPEstep,therewasnecessarytoselect:
the preconcentrationcolumn(typeandchemistryofthesorbent),
composition ofthewashingmobilephase(water-organicsolvent
ratio), flowrate,washingtimeandvolumeofsampleinjection,
selecting theoptimalconditionstoobtainastrongretentionof
analytesoncolumnandmatrixcomponentinterferenceelution