The distribution constants of PAR and Chrome Azurol S between micellar and aqueous phases, for cetyltrimethylammonium bromide and its mixtures with nonionic surfactants at a particular acidity were determine The relation between the distribution constants and the sensitivity of the color reaction was studied. An increase of the distribution constant of the ligand in the micellar phases is one of the main causes of the synergic sensitizing effect of mixed ionic-nonionic surfactants on color reaction. The mechanism of the synergic sensitizing effect of mixed surfactants on color reactions is discussed further.

Key words: SENSITIVITY, SURFACTANTS, CONCENTRATION, TRIMETHYLALKYLAMMONIUM, COLOR REACTION, BROMIDE, CHROME AZUROLS, NON IONIC SURFACTANTS, PYRIDINE AZO RESORCINOL, MICELLAR SOLUTION