The dansylation reaction of endocrine-disruptive alkylphenols on a C-18-modified silica act (ODS) instead of organic solvents was investigated with the aim of developing an environment-friendly and efficient derivatization method for the HPLC analyses. The solid-phase aqueous dansylation system has been incorporated into a preconcentration step performed by solid-phase extraction (SPE) from tap water.