New Potentiometric Sensor for Determination of Low Levels of Anionic Surfactants in Industrial Effluents

The new surfactant sensor based on tetrahexaclecylammonium dodecylsulfate as sensing ion-exchange complex, incorporated in plasticised PVC-membrane, has been used for potentiometric titration of low level anionic surfactants. The sensor exhibited near Nernstian response for dodecylsulfate (55.7 mV/decade) in the range 1.4(.)10(-6)-5.6(.)10(-3) mol/L and 57.3 mV/decade for dodecylbenzensulfonate in the range 1.9(.)10(-6)-1.6(.)10(-3) mol/L. There are no significant interferences from organic and inorganic anions, commonly used in surfactant based industrial and household formulations at anionic surfactant potentiometric determination. The solutions of low levels (down to 10(-5) mol/L) anionic surfactants (dodecylbenzensulfonate and dodecylsulfate) were successfully titrated with 1,3-didecyl-2-methylimidazolium chloride as standard cationic titrant. The sensor was used for determination of anionic surfactants in diluted industrial detergent products and industrial waste waters. The results obtained agree satisfactory with standard extraction-spectrophotometric MBAS method and are comparable with those obtained using a commercial surfactant electrode.