Here is an attempt to establish that a close relation exists between the chemical formulae of organophosphates and their affinities for lipids, proteins and water. We carried out this study on two systems similar to human plasma. First, each component was sorted, then the organophosphates were detected and titrated by gas chromatography with flame photometry detector. Thiophosphates had a greater affinity for lipids than phosphates. Fixation of proteins was only observed on three hydrophilous organophosphates: phosphamidon, dichlorvos, ciodrin.